2007-08-17 Maxim Grigoriev <maxim2405@gmail.com>

	* xtensa-tdep.c (ARG_NOF, ARG_1ST, PS_WOE, PS_EXC, C0_MAXOPDS)
	(C0_NREGS, C0_CLESV, C0_SP, C0_FP, C0_RA, C0_ARGS, C0_NARGS)
	(C0_CONST, C0_INEXP, C0_NOSTK): New macros.
	(xtensa_read_register): New function.
	(xtensa_windowed_frame_cache, xtensa_call0_frame_cache, xtensa_c0reg)
	(xtensa_insn_kind): New types.
	(xtensa_frame_cache, xtensa_alloc_frame_cache, xtensa_frame_cache)
	(xtensa_frame_prev_register, xtensa_return_value, xtensa_skip_prologue)
	(xtensa_verify_config, xtensa_pseudo_register_read)
	(xtensa_pseudo_register_write, xtensa_extract_return_value)
	(xtensa_store_return_value)
	(xtensa_push_dummy_call): Extended to support Xtensa Call0 ABI.
	(windowing_enabled, extract_call_winsize, xtensa_unwind_dummy_id)
	(xtensa_frame_this_id, xtensa_frame_prev_register)
	(xtensa_register_type, xtensa_reg_to_regnum): Cosmetic changes.
	(call0_frame_cache, call0_frame_get_reg_at_entry)
	(call0_classify_opcode, call0_track_op)
	(call0_analyze_prologue, call0_frame_cache): New functions.

1 files changed, 1022 insertions, 291 deletions

diff --git a/gdb/xtensa-tdep.c b/gdb/xtensa-tdep.c
index c52aa14..c5c62f9 100644
--- a/gdb/xtensa-tdep.c
+++ b/gdb/xtensa-tdep.c
@@ -51,6 +51,7 @@
 #include "gdbcmd.h"
 #include "gdb_assert.h"
 
+#include "xtensa-isa.h"
 #include "xtensa-tdep.h"
 
 
@@ -74,32 +75,31 @@ static int xtensa_debug_level = 0;
 
 
 /* According to the ABI, the SP must be aligned to 16-byte boundaries.  */
-
 #define SP_ALIGNMENT 16
 
 
-/* We use a6 through a11 for passing arguments to a function called by GDB.  */
-
-#define ARGS_FIRST_REG    A6_REGNUM
-#define ARGS_NUM_REGS     6
-#define REGISTER_SIZE	  4
-
+/* On Windowed ABI, we use a6 through a11 for passing arguments
+   to a function called by GDB because CALL4 is used.  */
+#define ARGS_FIRST_REG		A6_REGNUM
+#define ARGS_NUM_REGS		6
+#define REGISTER_SIZE		4
 
-/* Extract the call size from the return address or ps register.  */
 
-#define PS_CALLINC_SHIFT 16
-#define PS_CALLINC_MASK 0x00030000
-#define CALLINC(ps) (((ps) & PS_CALLINC_MASK) >> PS_CALLINC_SHIFT)
-#define WINSIZE(ra) (4 * (( (ra) >> 30) & 0x3))
+/* Extract the call size from the return address or PS register.  */
+#define PS_CALLINC_SHIFT	16
+#define PS_CALLINC_MASK		0x00030000
+#define CALLINC(ps)		(((ps) & PS_CALLINC_MASK) >> PS_CALLINC_SHIFT)
+#define WINSIZE(ra)		(4 * (( (ra) >> 30) & 0x3))
 
 
 /* Convert a live Ax register number to the corresponding Areg number.  */
-
 #define AREG_NUMBER(r, wb) \
-  ((((r) - A0_REGNUM + (((wb) & WB_MASK)<<WB_SHIFT)) & AREGS_MASK) + AR_BASE)
-
+  ((((r) - A0_REGNUM + (((wb) & WB_MASK) << WB_SHIFT)) & AREGS_MASK) + AR_BASE)
 
-/* Define prototypes.  */
+/* ABI-independent macros.  */
+#define ARG_NOF	    (CALL_ABI == CallAbiCall0Only ? C0_NARGS : (ARGS_NUM_REGS))
+#define ARG_1ST	    (CALL_ABI == CallAbiCall0Only \
+		     ? (A0_REGNUM) + C0_ARGS : (ARGS_FIRST_REG))
 
 extern struct gdbarch_tdep *xtensa_config_tdep (struct gdbarch_info *);
 extern int xtensa_config_byte_order (struct gdbarch_info *);
@@ -112,24 +112,26 @@ extern int xtensa_config_byte_order (struct gdbarch_info *);
   ((gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG) \
    ? ((op1) == 0x6c) : ((op1) == 0x36))
 
-#define XTENSA_ENTRY_LENGTH  3
-
+#define XTENSA_ENTRY_LENGTH	3
 
 /* windowing_enabled() returns true, if windowing is enabled.
    WOE must be set to 1; EXCM to 0.
    Note: We assume that EXCM is always 0 for XEA1.  */
 
+#define PS_WOE			(1<<18)
+#define PS_EXC			(1<<4)
+
 static inline int
 windowing_enabled (CORE_ADDR ps)
 {
-  return ((ps & (1 << 4)) == 0 && (ps & (1 << 18)) != 0);
+  return ((ps & PS_EXC) == 0 && (ps & PS_WOE) != 0);
 }
 
 /* Return the window size of the previous call to the function from which we
    have just returned.
 
    This function is used to extract the return value after a called function
-   has returned to the callee.  On Xtensa, the register that holds the return
+   has returned to the caller.  On Xtensa, the register that holds the return
    value (from the perspective of the caller) depends on what call
    instruction was used.  For now, we are assuming that the call instruction
    precedes the current address, so we simply analyze the call instruction.
@@ -139,7 +141,7 @@ windowing_enabled (CORE_ADDR ps)
 static int
 extract_call_winsize (CORE_ADDR pc)
 {
-  int winsize = 4;	/* Default: No call, e.g. dummy frame.  */
+  int winsize = 4;
   int insn;
   gdb_byte buf[4];
 
@@ -157,18 +159,15 @@ extract_call_winsize (CORE_ADDR pc)
        call{0,4,8,12}   0101 || {00,01,10,11} || OFFSET
        callx{0,4,8,12}  0000 || {00,01,10,11} || 11 || OFFSET.  */
 
-  /* Lookup call insn.
-     (Return the default value (4) if we can't find a valid call insn.  */
-
   if (gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_LITTLE)
     {
       if (((insn & 0xf) == 0x5) || ((insn & 0xcf) == 0xc0))
-	winsize = (insn & 0x30) >> 2;   /* 0, 4, 8, 12  */
+	winsize = (insn & 0x30) >> 2;   /* 0, 4, 8, 12.  */
     }
   else
     {
       if (((insn >> 20) == 0x5) || (((insn >> 16) & 0xf3) == 0x03))
-	winsize = (insn >> 16) & 0xc;   /* 0, 4, 8, 12  */
+	winsize = (insn >> 16) & 0xc;   /* 0, 4, 8, 12.  */
     }
   return winsize;
 }
@@ -177,7 +176,6 @@ extract_call_winsize (CORE_ADDR pc)
 /* REGISTER INFORMATION */
 
 /* Returns the name of a register.  */
-
 static const char *
 xtensa_register_name (int regnum)
 {
@@ -186,11 +184,18 @@ xtensa_register_name (int regnum)
 			      + gdbarch_num_pseudo_regs (current_gdbarch))
     return REGMAP[regnum].name;
 
-  /* Invalid register number.  */
   internal_error (__FILE__, __LINE__, _("invalid register %d"), regnum);
   return 0;
 }
 
+static unsigned long
+xtensa_read_register (int regnum)
+{
+  ULONGEST value;
+
+  regcache_raw_read_unsigned (get_current_regcache (), regnum, &value);
+  return (unsigned long) value;
+}
 
 /* Return the type of a register.  Create a new type, if necessary.  */
 
@@ -218,15 +223,15 @@ xtensa_register_type (struct gdbarch *gdbarch, int regnum)
     {
       xtensa_register_t* reg = &REGMAP[regnum];
 
-      /* Set ctype for this register (only the first time we ask for it).  */
+      /* Set ctype for this register (only the first time).  */
 
       if (reg->ctype == 0)
 	{
 	  struct ctype_cache *tp;
 	  int size = reg->byte_size;
 
-	  /* We always use the memory representation, even if the register
-	     width is smaller.  */
+	  /* We always use the memory representation,
+	     even if the register width is smaller.  */
 	  switch (size)
 	    {
 	    case 1:
@@ -274,13 +279,12 @@ xtensa_register_type (struct gdbarch *gdbarch, int regnum)
       return reg->ctype;
     }
 
-  /* Invalid register number.  */
   internal_error (__FILE__, __LINE__, _("invalid register number %d"), regnum);
   return 0;
 }
 
 
-/* Returns the 'local' register number for stubs, dwarf2, etc.
+/* Return the 'local' register number for stubs, dwarf2, etc.
    The debugging information enumerates registers starting from 0 for A0
    to n for An.  So, we only have to add the base number for A0.  */
 
@@ -299,26 +303,22 @@ xtensa_reg_to_regnum (int regnum)
     if (regnum == REGMAP[i].target_number)
       return i;
 
-  /* Invalid register number.  */
   internal_error (__FILE__, __LINE__,
 		  _("invalid dwarf/stabs register number %d"), regnum);
   return 0;
 }
 
 
-/* Handle the special case of masked registers.  */
-
-/* Write the bits of a masked register to the various registers that
-   are combined into this register.  Only the masked areas of these
-   registers are modified; the other fields are untouched.
-   (Note: The size of masked registers is always less or equal 32 bits.)  */
+/* Write the bits of a masked register to the various registers.
+   Only the masked areas of these registers are modified; the other
+   fields are untouched.  The size of masked registers is always less
+   than or equal to 32 bits.  */
 
 static void
 xtensa_register_write_masked (struct regcache *regcache,
 			      xtensa_register_t *reg, const gdb_byte *buffer)
 {
   unsigned int value[(MAX_REGISTER_SIZE + 3) / 4];
-
   const xtensa_mask_t *mask = reg->mask;
 
   int shift = 0;		/* Shift for next mask (mod 32).  */
@@ -395,15 +395,14 @@ xtensa_register_write_masked (struct regcache *regcache,
 }
 
 
-/* Read the masked areas of the registers and assemble it into a single
-   register.  */
+/* Read a tie state or mapped registers.  Read the masked areas
+   of the registers and assemble them into a single value.  */
 
 static void
 xtensa_register_read_masked (struct regcache *regcache,
 			     xtensa_register_t *reg, gdb_byte *buffer)
 {
   unsigned int value[(MAX_REGISTER_SIZE + 3) / 4];
-
   const xtensa_mask_t *mask = reg->mask;
 
   int shift = 0;
@@ -495,12 +494,12 @@ xtensa_pseudo_register_read (struct gdbarch *gdbarch,
   DEBUGTRACE ("xtensa_pseudo_register_read (... regnum = %d (%s) ...)\n",
 	      regnum, xtensa_register_name (regnum));
 
-  /* Check if it is FP (renumber it in this case -> A0...A15).  */
   if (regnum == FP_ALIAS)
-    error (_("trying to read FP"));
+     regnum = A1_REGNUM;
 
-  /* Read aliases a0..a15.  */
-  if (regnum >= A0_REGNUM && regnum <= A15_REGNUM)
+  /* Read aliases a0..a15, if this is a Windowed ABI.  */
+  if (ISA_USE_WINDOWED_REGISTERS
+      && (regnum >= A0_REGNUM) && (regnum <= A15_REGNUM))
     {
       gdb_byte *buf = (gdb_byte *) alloca (MAX_REGISTER_SIZE);
 
@@ -508,7 +507,7 @@ xtensa_pseudo_register_read (struct gdbarch *gdbarch,
       regnum = AREG_NUMBER (regnum, extract_unsigned_integer (buf, 4));
     }
 
-  /* We can always read 'regular' registers.  */
+  /* We can always read non-pseudo registers.  */
   if (regnum >= 0 && regnum < gdbarch_num_regs (current_gdbarch))
     regcache_raw_read (regcache, regnum, buffer);
 
@@ -521,7 +520,7 @@ xtensa_pseudo_register_read (struct gdbarch *gdbarch,
       xtensa_register_type_t type = reg->type;
       int flags = XTENSA_TARGET_FLAGS;
 
-      /* Can we read Unknown or Unmapped registers?  */
+      /* We cannot read Unknown or Unmapped registers.  */
       if (type == xtRegisterTypeUnmapped || type == xtRegisterTypeUnknown)
 	{
 	  if ((flags & xtTargetFlagsNonVisibleRegs) == 0)
@@ -560,7 +559,6 @@ xtensa_pseudo_register_read (struct gdbarch *gdbarch,
       /* Assume that we can read the register.  */
       regcache_raw_read (regcache, regnum, buffer);
     }
-
   else
     internal_error (__FILE__, __LINE__,
 		    _("invalid register number %d"), regnum);
@@ -578,12 +576,12 @@ xtensa_pseudo_register_write (struct gdbarch *gdbarch,
   DEBUGTRACE ("xtensa_pseudo_register_write (... regnum = %d (%s) ...)\n",
 	      regnum, xtensa_register_name (regnum));
 
-  /* Check if this is FP.  */
   if (regnum == FP_ALIAS)
-    error (_("trying to write FP"));
+     regnum = A1_REGNUM;
 
-  /* Renumber register, if aliase a0..a15.  */
-  if (regnum >= A0_REGNUM && regnum <= A15_REGNUM)
+  /* Renumber register, if aliase a0..a15 on Windowed ABI.  */
+  if (ISA_USE_WINDOWED_REGISTERS
+      && (regnum >= A0_REGNUM) && (regnum <= A15_REGNUM))
     {
       gdb_byte *buf = (gdb_byte *) alloca (MAX_REGISTER_SIZE);
       unsigned int wb;
@@ -606,8 +604,8 @@ xtensa_pseudo_register_write (struct gdbarch *gdbarch,
       xtensa_register_type_t type = reg->type;
       int flags = XTENSA_TARGET_FLAGS;
 
-      /* On most targets, we can't write registers of type "Unknown"
-	 or "Unmapped".  */
+      /* On most targets, we cannot write registers
+	 of type "Unknown" or "Unmapped".  */
       if (type == xtRegisterTypeUnmapped || type == xtRegisterTypeUnknown)
         {
 	  if ((flags & xtTargetFlagsNonVisibleRegs) == 0)
@@ -630,7 +628,6 @@ xtensa_pseudo_register_write (struct gdbarch *gdbarch,
 
 	  /* On some targets (esp. simulators), we can always write
 	     the register.  */
-
 	  else if ((flags & xtTargetFlagsNonVisibleRegs) == 0)
 	    {
 	      warning (_("cannot write register"));
@@ -648,13 +645,11 @@ xtensa_pseudo_register_write (struct gdbarch *gdbarch,
       /* Assume that we can write the register.  */
       regcache_raw_write (regcache, regnum, buffer);
     }
-
   else
     internal_error (__FILE__, __LINE__,
 		    _("invalid register number %d"), regnum);
 }
 
-
 static struct reggroup *xtensa_ar_reggroup;
 static struct reggroup *xtensa_user_reggroup;
 static struct reggroup *xtensa_vectra_reggroup;
@@ -760,11 +755,9 @@ xtensa_register_reggroup_p (struct gdbarch *gdbarch,
 }
 
 
-/* CORE FILE SUPPORT */
-
 /* Supply register REGNUM from the buffer specified by GREGS and LEN
    in the general-purpose register set REGSET to register cache
-   REGCACHE.  If REGNUM is -1, do this for all registers in REGSET.  */
+   REGCACHE.  If REGNUM is -1 do this for all registers in REGSET.  */
 
 static void
 xtensa_supply_gregset (const struct regset *regset,
@@ -821,8 +814,8 @@ xtensa_gregset =
 };
 
 
-/* Return the appropriate register set for the core section identified
-   by SECT_NAME and SECT_SIZE.  */
+/* Return the appropriate register set for the core
+   section identified by SECT_NAME and SECT_SIZE.  */
 
 static const struct regset *
 xtensa_regset_from_core_section (struct gdbarch *core_arch,
@@ -831,7 +824,7 @@ xtensa_regset_from_core_section (struct gdbarch *core_arch,
 {
   DEBUGTRACE ("xtensa_regset_from_core_section "
 	      "(..., sect_name==\"%s\", sect_size==%x) \n",
-	      sect_name, (int) sect_size);
+	      sect_name, sect_size);
 
   if (strcmp (sect_name, ".reg") == 0
       && sect_size >= sizeof(xtensa_elf_gregset_t))
@@ -841,29 +834,82 @@ xtensa_regset_from_core_section (struct gdbarch *core_arch,
 }
 
 
-/* F R A M E */
+/* Handling frames.  */
 
-/* We currently don't support the call0-abi, so we have at max. 12 registers
-   saved on the stack.  */
+/* Number of registers to save in case of Windowed ABI.  */
+#define XTENSA_NUM_SAVED_AREGS		12
 
-#define XTENSA_NUM_SAVED_AREGS 12
-
-typedef struct xtensa_frame_cache
+/* Frame cache part for Windowed ABI.  */
+typedef struct xtensa_windowed_frame_cache
 {
-  CORE_ADDR base;
-  CORE_ADDR pc;
-  CORE_ADDR ra;		/* The raw return address; use to compute call_inc.  */
-  CORE_ADDR ps;
   int wb;		/* Base for this frame; -1 if not in regfile.  */
   int callsize;		/* Call size to next frame.  */
   int ws;
   CORE_ADDR aregs[XTENSA_NUM_SAVED_AREGS];
-  CORE_ADDR prev_sp;
+} xtensa_windowed_frame_cache_t;
+
+/* Call0 ABI Definitions.  */
+
+#define C0_MAXOPDS  3	/* Maximum number of operands for prologue analysis.  */
+#define C0_NREGS   16	/* Number of A-registers to track.  */
+#define C0_CLESV   12	/* Callee-saved registers are here and up.  */
+#define C0_SP	    1	/* Register used as SP.  */
+#define C0_FP	   15	/* Register used as FP.  */
+#define C0_RA	    0	/* Register used as return address.  */
+#define C0_ARGS	    2	/* Register used as first arg/retval.  */
+#define C0_NARGS    6	/* Number of A-regs for args/retvals.  */
+
+/* Each element of xtensa_call0_frame_cache.c0_rt[] describes for each
+   A-register where the current content of the reg came from (in terms
+   of an original reg and a constant).  Negative values of c0_rt[n].fp_reg
+   mean that the orignal content of the register was saved to the stack.
+   c0_rt[n].fr.ofs is NOT the offset from the frame base because we don't 
+   know where SP will end up until the entire prologue has been analyzed.  */
+
+#define C0_CONST   -1	/* fr_reg value if register contains a constant.  */
+#define C0_INEXP   -2	/* fr_reg value if inexpressible as reg + offset.  */
+#define C0_NOSTK   -1	/* to_stk value if register has not been stored.  */
+
+extern xtensa_isa xtensa_default_isa;
+
+typedef struct xtensa_c0reg
+{
+    int	    fr_reg;	/* original register from which register content
+			   is derived, or C0_CONST, or C0_INEXP.  */
+    int	    fr_ofs;	/* constant offset from reg, or immediate value.  */
+    int	    to_stk;	/* offset from original SP to register (4-byte aligned),
+			   or C0_NOSTK if register has not been saved.  */
+} xtensa_c0reg_t;
+
+
+/* Frame cache part for Call0 ABI.  */
+typedef struct xtensa_call0_frame_cache
+{
+  int c0_frmsz;				/* Stack frame size.  */
+  int c0_hasfp;				/* Current frame uses frame pointer.  */
+  int fp_regnum;			/* A-register used as FP.  */
+  int c0_fp;				/* Actual value of frame pointer.  */
+  xtensa_c0reg_t c0_rt[C0_NREGS];	/* Register tracking information.  */
+} xtensa_call0_frame_cache_t;
+
+typedef struct xtensa_frame_cache
+{
+  CORE_ADDR base;	/* Stack pointer of the next frame.  */
+  CORE_ADDR pc;		/* PC at the entry point to the function.  */
+  CORE_ADDR ra;		/* The raw return address.  */
+  CORE_ADDR ps;		/* The PS register of the frame.  */
+  CORE_ADDR prev_sp;	/* Stack Pointer of the frame.  */
+  int call0;		/* It's a call0 framework (else windowed).  */
+  union
+    {
+      xtensa_windowed_frame_cache_t	wd;	/* call0 == false.  */
+      xtensa_call0_frame_cache_t       	c0;	/* call0 == true.  */
+    };
 } xtensa_frame_cache_t;
 
 
 static struct xtensa_frame_cache *
-xtensa_alloc_frame_cache (void)
+xtensa_alloc_frame_cache (int windowed)
 {
   xtensa_frame_cache_t *cache;
   int i;
@@ -875,14 +921,31 @@ xtensa_alloc_frame_cache (void)
   cache->base = 0;
   cache->pc = 0;
   cache->ra = 0;
-  cache->wb = 0;
   cache->ps = 0;
-  cache->callsize = -1;
   cache->prev_sp = 0;
+  cache->call0 = !windowed;
+  if (cache->call0)
+    {
+      cache->c0.c0_frmsz  = -1;
+      cache->c0.c0_hasfp  =  0;
+      cache->c0.fp_regnum = -1;
+      cache->c0.c0_fp     = -1;
 
-  for (i = 0; i < XTENSA_NUM_SAVED_AREGS; i++)
-    cache->aregs[i] = -1;
+      for (i = 0; i < C0_NREGS; i++)
+	{
+	  cache->c0.c0_rt[i].fr_reg = i;
+	  cache->c0.c0_rt[i].fr_ofs = 0;
+	  cache->c0.c0_rt[i].to_stk = C0_NOSTK;
+	}
+    }
+  else
+    {
+      cache->wd.wb = 0;
+      cache->wd.callsize = -1;
 
+      for (i = 0; i < XTENSA_NUM_SAVED_AREGS; i++)
+	cache->wd.aregs[i] = -1;
+    }
   return cache;
 }
 
@@ -914,141 +977,149 @@ static struct frame_id
 xtensa_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info *next_frame)
 {
   CORE_ADDR pc, fp;
-  gdb_byte buf[4];
 
-  /* next_frame->prev is a dummy frame. Return a frame ID of that frame.  */
+  /* next_frame->prev is a dummy frame.  Return a frame ID of that frame.  */
 
   DEBUGTRACE ("xtensa_unwind_dummy_id ()\n");
 
   pc = frame_pc_unwind (next_frame);
-  frame_unwind_register (next_frame, A1_REGNUM, buf);
-  fp = extract_unsigned_integer (buf, 4);
+  fp = frame_unwind_register_unsigned (next_frame, A1_REGNUM);
 
   /* Make dummy frame ID unique by adding a constant.  */
-  return frame_id_build (fp+SP_ALIGNMENT, pc);
+  return frame_id_build (fp + SP_ALIGNMENT, pc);
 }
 
+/* The key values to identify the frame using "cache" are 
+
+	cache->base    = SP of this frame;
+	cache->pc      = entry-PC (entry point of the frame function);
+	cache->prev_sp = SP of the previous frame.
+*/
+
+static void
+call0_frame_cache (struct frame_info *next_frame,
+		   xtensa_frame_cache_t *cache,
+		   CORE_ADDR pc);
 
 static struct xtensa_frame_cache *
 xtensa_frame_cache (struct frame_info *next_frame, void **this_cache)
 {
   xtensa_frame_cache_t *cache;
-  char buf[4];
   CORE_ADDR ra, wb, ws, pc, sp, ps;
+  unsigned int ps_regnum = gdbarch_ps_regnum (current_gdbarch);
   char op1;
+  int  windowed;
 
   DEBUGTRACE ("xtensa_frame_cache (next_frame %p, *this_cache %p)\n",
 	      next_frame, this_cache ? *this_cache : (void*)0xdeadbeef);
 
-  /* Already cached?  */
   if (*this_cache)
     return *this_cache;
 
+  windowed = windowing_enabled (xtensa_read_register (ps_regnum));
+
   /* Get pristine xtensa-frame.  */
-  cache = xtensa_alloc_frame_cache ();
+  cache = xtensa_alloc_frame_cache (windowed);
   *this_cache = cache;
 
-  /* Get windowbase, windowstart, ps, and pc.  */
-  wb = frame_unwind_register_unsigned (next_frame, WB_REGNUM);
-  ws = frame_unwind_register_unsigned (next_frame, WS_REGNUM);
-  ps = frame_unwind_register_unsigned (next_frame,
-				       gdbarch_ps_regnum (current_gdbarch));
   pc = frame_unwind_register_unsigned (next_frame,
 				       gdbarch_pc_regnum (current_gdbarch));
 
-  op1 = read_memory_integer (pc, 1);
-  if (XTENSA_IS_ENTRY (op1) || !windowing_enabled (ps))
-    {
-      int callinc = CALLINC (ps);
-      ra = frame_unwind_register_unsigned (next_frame,
-					   A0_REGNUM + callinc * 4);
-
-      DEBUGINFO("[xtensa_frame_cache] 'entry' at 0x%08x\n (callinc = %d)",
-	  	(int)pc, callinc);
-
-      /* ENTRY hasn't been executed yet, therefore callsize is still 0.  */
-      cache->callsize = 0;
-      cache->wb = wb;
-      cache->ws = ws;
-      cache->prev_sp = frame_unwind_register_unsigned (next_frame, A1_REGNUM);
-    }
-  else
-    {
-      ra = frame_unwind_register_unsigned (next_frame, A0_REGNUM);
-      cache->callsize = WINSIZE (ra);
-      cache->wb = (wb - (cache->callsize / 4)) & ((NUM_AREGS / 4) - 1);
-      cache->ws = ws & ~(1 << wb);
-    }
-
-  cache->pc = ((frame_func_unwind (next_frame, NORMAL_FRAME) & 0xc0000000)
-	       | (ra & 0x3fffffff));
-  cache->ps = (ps & ~PS_CALLINC_MASK) | ((WINSIZE(ra)/4) << PS_CALLINC_SHIFT);
-
-
-  /* Note: We could also calculate the location on stack when we actually
-     access the register.  However, this approach, saving the location
-     in the cache frame, is probably easier to support the call0 ABI.  */
-
-  if (cache->ws == 0)
+  if (windowed)
     {
-      int i;
+      /* Get WINDOWBASE, WINDOWSTART, and PS registers.  */
+      wb = frame_unwind_register_unsigned (next_frame, WB_REGNUM);
+      ws = frame_unwind_register_unsigned (next_frame, WS_REGNUM);
+      ps = frame_unwind_register_unsigned (next_frame, ps_regnum);
 
-      /* Set A0...A3.  */
-      sp = frame_unwind_register_unsigned (next_frame, A1_REGNUM) - 16;
-
-      for (i = 0; i < 4; i++, sp += 4)
+      op1 = read_memory_integer (pc, 1);
+      if (XTENSA_IS_ENTRY (op1))
 	{
-	  cache->aregs[i] = sp;
+	  int callinc = CALLINC (ps);
+	  ra = frame_unwind_register_unsigned (next_frame,
+					       A0_REGNUM + callinc * 4);
+	  
+	  DEBUGINFO("[xtensa_frame_cache] 'entry' at 0x%08x\n (callinc = %d)",
+		    (int)pc, callinc);
+	  
+	  /* ENTRY hasn't been executed yet, therefore callsize is still 0.  */
+	  cache->wd.callsize = 0;
+	  cache->wd.wb = wb;
+	  cache->wd.ws = ws;
+	  cache->prev_sp = frame_unwind_register_unsigned (next_frame,
+							   A1_REGNUM);
+	}
+      else
+	{
+	  ra = frame_unwind_register_unsigned (next_frame, A0_REGNUM);
+	  cache->wd.callsize = WINSIZE (ra);
+	  cache->wd.wb = (wb - cache->wd.callsize / 4) & (NUM_AREGS / 4 - 1);
+	  cache->wd.ws = ws & ~(1 << wb);
 	}
 
-      if (cache->callsize > 4)
+      cache->pc = frame_func_unwind (next_frame, NORMAL_FRAME);
+      cache->ra = (cache->pc & 0xc0000000) | (ra & 0x3fffffff);
+      cache->ps = (ps & ~PS_CALLINC_MASK)
+	| ((WINSIZE(ra)/4) << PS_CALLINC_SHIFT);
+
+      if (cache->wd.ws == 0)
 	{
-	  /* Set A4...A7/A11.  */
+	  int i;
 
-	  sp = (CORE_ADDR) read_memory_integer (sp - 12, 4);
-	  sp = (CORE_ADDR) read_memory_integer (sp - 12, 4);
-	  sp -= cache->callsize * 4;
+	  /* Set A0...A3.  */
+	  sp = frame_unwind_register_unsigned (next_frame, A1_REGNUM) - 16;
+	  
+	  for (i = 0; i < 4; i++, sp += 4)
+	    {
+	      cache->wd.aregs[i] = sp;
+	    }
 
-	  for ( /* i=4  */ ; i < cache->callsize; i++, sp += 4)
+	  if (cache->wd.callsize > 4)
 	    {
-	      cache->aregs[i] = sp;
+	      /* Set A4...A7/A11.  */
+	      /* Read an SP of the previous frame.  */
+	      sp = (CORE_ADDR) read_memory_integer (sp - 12, 4);
+	      sp -= cache->wd.callsize * 4;
+
+	      for ( /* i=4  */ ; i < cache->wd.callsize; i++, sp += 4)
+		{
+		  cache->wd.aregs[i] = sp;
+		}
 	    }
 	}
-    }
 
-  if (cache->prev_sp == 0) 
-    {
-      if (cache->ws == 0)
-	{
-	  /* Register window overflow already happened.
-	     We can read caller's frame SP from the proper spill loction.  */
-	  cache->prev_sp =
-		  read_memory_integer (cache->aregs[1],
-				       register_size (current_gdbarch,
-						      A1_REGNUM));
-	}
-      else
+      if ((cache->prev_sp == 0) && ( ra != 0 ))
+	/* If RA is equal to 0 this frame is an outermost frame.  Leave
+	   cache->prev_sp unchanged marking the boundary of the frame stack.  */
 	{
-	  /* Read caller's frame SP directly from the previous window.  */
-
-	  int regnum = AREG_NUMBER (A1_REGNUM, cache->wb);
+	  if (cache->wd.ws == 0)
+	    {
+	      /* Register window overflow already happened.
+		 We can read caller's SP from the proper spill loction.  */
+	      cache->prev_sp =
+		read_memory_integer (cache->wd.aregs[1],
+				     register_size (current_gdbarch,
+						    A1_REGNUM));
+	    }
+	  else
+	    {
+	      /* Read caller's frame SP directly from the previous window.  */
+	      int regnum = AREG_NUMBER (A1_REGNUM, cache->wd.wb);
 
-	  cache->prev_sp = frame_unwind_register_unsigned (next_frame, regnum);
+	      cache->prev_sp = xtensa_read_register (regnum);
+	    }
 	}
     }
+  else	/* Call0 framework.  */
+    {
+      call0_frame_cache (next_frame, cache, pc);
+    }
 
   cache->base = frame_unwind_register_unsigned (next_frame,A1_REGNUM);
 
-  DEBUGINFO ("[xtensa_frame_cache] base 0x%08x, wb %d, "
-	     "ws 0x%08x, callsize %d, pc 0x%08x, ps 0x%08x, prev_sp 0x%08x\n",
-	     (unsigned int) cache->base, (unsigned int) cache->wb,
-	     cache->ws, cache->callsize, (unsigned int) cache->pc,
-	     (unsigned int) cache->ps, (unsigned int) cache->prev_sp);
-
   return cache;
 }
 
-
 static void
 xtensa_frame_this_id (struct frame_info *next_frame,
 		      void **this_cache,
@@ -1056,16 +1127,70 @@ xtensa_frame_this_id (struct frame_info *next_frame,
 {
   struct xtensa_frame_cache *cache =
     xtensa_frame_cache (next_frame, this_cache);
+  struct frame_id id;
 
-  DEBUGTRACE ("xtensa_frame_this_id (next %p, *this %p)\n",
-	      next_frame, *this_cache);
+  DEBUGTRACE ("xtensa_frame_this_id (next 0x%08x, *this 0x%08x)\n",
+	      (unsigned int) next_frame, (unsigned int) *this_cache);
 
   if (cache->prev_sp == 0)
     return;
 
-  (*this_id) = frame_id_build (cache->prev_sp, cache->pc);
+  id = frame_id_build (cache->prev_sp, cache->pc);
+  if (frame_id_eq (id, get_frame_id(next_frame)))
+    {
+      warning(_("\
+Frame stack is corrupted. That could happen because of \
+setting register(s) from GDB or stopping execution \
+inside exception handler. Frame backtracing has stopped. \
+It can make some GDB commands work inappropriately.\n"));
+      cache->prev_sp = 0;
+      return;
+    }
+  (*this_id) = id;
 }
 
+static int
+call0_frame_get_reg_at_entry (struct frame_info *next_frame,
+			      struct xtensa_frame_cache *cache,
+			      int regnum, 
+			      CORE_ADDR *addrp,
+			      enum lval_type *lval,
+			      gdb_byte *valuep)
+{
+  CORE_ADDR fp, spe;
+  int stkofs;
+  int reg = (regnum >= AR_BASE && regnum <= (AR_BASE + C0_NREGS))
+    		? regnum - AR_BASE : regnum;
+
+  /* Determine stack pointer on entry to this function, based on FP.  */
+  spe = cache->c0.c0_fp - cache->c0.c0_rt[cache->c0.fp_regnum].fr_ofs;
+
+  /* If register was saved to the stack frame in the prologue, retrieve it.  */
+  stkofs = cache->c0.c0_rt[reg].to_stk;
+  if (stkofs != C0_NOSTK)
+    {
+      *lval = lval_memory;
+      *addrp = spe + stkofs;
+
+      if (valuep)
+	read_memory (*addrp, valuep, register_size (current_gdbarch, regnum));
+
+      return 1;
+    }
+
+  /* If not callee-saved or if known to have been overwritten, give up.  */
+  if (reg < C0_CLESV 
+      || cache->c0.c0_rt[reg].fr_reg != reg
+      || cache->c0.c0_rt[reg].fr_ofs != 0)
+    return 0;
+
+  if (get_frame_type (next_frame) != NORMAL_FRAME)
+    /* TODO: Do we need a special case for DUMMY_FRAME here?  */
+    return 0;
+
+  return call0_frame_get_reg_at_entry (get_next_frame(next_frame),
+				       cache, regnum, addrp, lval, valuep);
+}
 
 static void
 xtensa_frame_prev_register (struct frame_info *next_frame,
@@ -1082,25 +1207,32 @@ xtensa_frame_prev_register (struct frame_info *next_frame,
   CORE_ADDR saved_reg = 0;
   int done = 1;
 
-  DEBUGTRACE ("xtensa_frame_prev_register (next %p, "
-	      "*this %p, regnum %d (%s), ...)\n",
-	      next_frame,
-	      *this_cache ? *this_cache : 0, regnum,
+  DEBUGTRACE ("xtensa_frame_prev_register (next 0x%08x, "
+	      "*this 0x%08x, regnum %d (%s), ...)\n",
+	      (unsigned int) next_frame,
+	      *this_cache ? (unsigned int) *this_cache : 0, regnum,
 	      xtensa_register_name (regnum));
 
-  if (regnum == WS_REGNUM)
+  if (regnum ==gdbarch_pc_regnum (current_gdbarch))
+    saved_reg = cache->ra;
+  else if (regnum == A1_REGNUM)
+    saved_reg = cache->prev_sp;
+  else if (!cache->call0)
     {
-      if (cache->ws != 0)
-	saved_reg = cache->ws;
+      if (regnum == WS_REGNUM)
+	{
+	  if (cache->wd.ws != 0)
+	    saved_reg = cache->wd.ws;
+	  else
+	    saved_reg = 1 << cache->wd.wb;
+	}
+      else if (regnum == WB_REGNUM)
+	saved_reg = cache->wd.wb;
+      else if (regnum == gdbarch_ps_regnum (current_gdbarch))
+	saved_reg = cache->ps;
       else
-	saved_reg = 1 << cache->wb;
+	done = 0;
     }
-  else if (regnum == WB_REGNUM)
-    saved_reg = cache->wb;
-  else if (regnum == gdbarch_pc_regnum (current_gdbarch))
-    saved_reg = cache->pc;
-  else if (regnum == gdbarch_ps_regnum (current_gdbarch))
-    saved_reg = cache->ps;
   else
     done = 0;
 
@@ -1116,35 +1248,69 @@ xtensa_frame_prev_register (struct frame_info *next_frame,
       return;
     }
 
-  /* Convert Ax register numbers to ARx register numbers.  */
-  if (regnum >= A0_REGNUM && regnum <= A15_REGNUM)
-    regnum = AREG_NUMBER (regnum, cache->wb);
-
-  /* Check if ARx register has been saved to stack.  */
-  if (regnum >= AR_BASE && regnum <= (AR_BASE + NUM_AREGS))
+  if (!cache->call0) /* Windowed ABI.  */
     {
-      int areg = regnum - AR_BASE - (cache->wb * 4);
+      /* Convert A-register numbers to AR-register numbers.  */
+      if (regnum >= A0_REGNUM && regnum <= A15_REGNUM)
+	regnum = AREG_NUMBER (regnum, cache->wd.wb);
 
-      if (areg >= 0
-	  && areg < XTENSA_NUM_SAVED_AREGS
-	  && cache->aregs[areg] != -1)
-        {
-    	  *optimizedp = 0;
-	  *lvalp = lval_memory;
-	  *addrp = cache->aregs[areg];
-	  *realnump = -1;
+      /* Check if AR-register has been saved to stack.  */
+      if (regnum >= AR_BASE && regnum <= (AR_BASE + NUM_AREGS))
+	{
+	  int areg = regnum - AR_BASE - (cache->wd.wb * 4);
 
-	  if (valuep)
-	    read_memory (*addrp, valuep,
-			 register_size (current_gdbarch, regnum));
+	  if (areg >= 0
+	      && areg < XTENSA_NUM_SAVED_AREGS
+	      && cache->wd.aregs[areg] != -1)
+	    {
+	      *optimizedp = 0;
+	      *lvalp = lval_memory;
+	      *addrp = cache->wd.aregs[areg];
+	      *realnump = -1;
 
-	  DEBUGINFO ("[xtensa_frame_prev_register] register on stack\n");
-	  return;
+	      if (valuep)
+		read_memory (*addrp, valuep,
+			     register_size (current_gdbarch, regnum));
+
+	      DEBUGINFO ("[xtensa_frame_prev_register] register on stack\n");
+	      return;
+	    }
 	}
     }
+  else /* Call0 ABI.  */
+    {
+      int reg = (regnum >= AR_BASE && regnum <= (AR_BASE + C0_NREGS))
+			? regnum - AR_BASE : regnum;
 
-  /* Note: All other registers have been either saved to the dummy stack
-     or are still alive in the processor.  */
+      if (reg < C0_NREGS)
+	{
+	  CORE_ADDR spe;
+	  int stkofs;
+
+	  /* If register was saved in the prologue, retrieve it.  */
+	  stkofs = cache->c0.c0_rt[reg].to_stk;
+	  if (stkofs != C0_NOSTK)
+	    {
+	      /* Determine SP on entry based on FP.  */
+	      spe = cache->c0.c0_fp
+		- cache->c0.c0_rt[cache->c0.fp_regnum].fr_ofs;
+	      *optimizedp = 0;
+	      *lvalp = lval_memory;
+	      *addrp = spe + stkofs;
+	      *realnump = -1;
+	  
+	      if (valuep)
+		read_memory (*addrp, valuep,
+			     register_size (current_gdbarch, regnum));
+	  
+	      DEBUGINFO ("[xtensa_frame_prev_register] register on stack\n");
+	      return;
+	    }
+	}
+    }
+
+  /* All other registers have been either saved to
+     the stack or are still alive in the processor.  */
 
   *optimizedp = 0;
   *lvalp = lval_register;
@@ -1203,20 +1369,28 @@ xtensa_extract_return_value (struct type *type,
 
   gdb_assert(len > 0);
 
-  /* First, we have to find the caller window in the register file.  */
-  regcache_raw_read_unsigned (regcache,
+  if (CALL_ABI != CallAbiCall0Only)
+    {
+      /* First, we have to find the caller window in the register file.  */
+      regcache_raw_read_unsigned (regcache,
 			      gdbarch_pc_regnum (current_gdbarch), &pc);
-  callsize = extract_call_winsize (pc);
+      callsize = extract_call_winsize (pc);
 
-  /* On Xtensa, we can return up to 4 words (or 2 when called by call12).  */
-  if (len > (callsize > 8 ? 8 : 16))
-    internal_error (__FILE__, __LINE__,
-	            _("cannot extract return value of %d bytes long"), len);
+      /* On Xtensa, we can return up to 4 words (or 2 for call12).  */
+      if (len > (callsize > 8 ? 8 : 16))
+	internal_error (__FILE__, __LINE__,
+			_("cannot extract return value of %d bytes long"), len);
 
-  /* Get the register offset of the return register (A2) in the caller
-     window.  */
-  regcache_raw_read_unsigned (regcache, WB_REGNUM, &wb);
-  areg = AREG_NUMBER(A2_REGNUM + callsize, wb);
+      /* Get the register offset of the return
+	 register (A2) in the caller window.  */
+      regcache_raw_read_unsigned (regcache, WB_REGNUM, &wb);
+      areg = AREG_NUMBER(A2_REGNUM + callsize, wb);
+    }
+  else
+    {
+      /* No windowing hardware - Call0 ABI.  */
+      areg = A0_REGNUM + C0_ARGS;
+    }
 
   DEBUGINFO ("[xtensa_extract_return_value] areg %d len %d\n", areg, len);
 
@@ -1247,24 +1421,30 @@ xtensa_store_return_value (struct type *type,
 
   DEBUGTRACE ("xtensa_store_return_value (...)\n");
 
-  regcache_raw_read_unsigned (regcache, WB_REGNUM, &wb);
+  if (CALL_ABI != CallAbiCall0Only)
+    {
+      regcache_raw_read_unsigned (regcache, WB_REGNUM, &wb);
   regcache_raw_read_unsigned (regcache,
 			      gdbarch_pc_regnum (current_gdbarch), &pc);
-  callsize = extract_call_winsize (pc);
+      callsize = extract_call_winsize (pc);
 
-  if (len > (callsize > 8 ? 8 : 16))
-    internal_error (__FILE__, __LINE__,
-		    _("unimplemented for this length: %d"),
-		    TYPE_LENGTH (type));
+      if (len > (callsize > 8 ? 8 : 16))
+	internal_error (__FILE__, __LINE__,
+			_("unimplemented for this length: %d"),
+			TYPE_LENGTH (type));
+      areg = AREG_NUMBER (A2_REGNUM + callsize, wb);
 
-  DEBUGTRACE ("[xtensa_store_return_value] callsize %d wb %d\n",
+      DEBUGTRACE ("[xtensa_store_return_value] callsize %d wb %d\n",
               callsize, (int) wb);
+    }
+  else
+    {
+      areg = A0_REGNUM + C0_ARGS;
+    }
 
   if (len < 4 && gdbarch_byte_order (current_gdbarch) == BFD_ENDIAN_BIG)
     offset = 4 - len;
 
-  areg = AREG_NUMBER (A2_REGNUM + callsize, wb);
-
   for (; len > 0; len -= 4, areg++, valbuf += 4)
     {
       if (len < 4)
@@ -1275,14 +1455,14 @@ xtensa_store_return_value (struct type *type,
 }
 
 
-enum return_value_convention
+static enum return_value_convention
 xtensa_return_value (struct gdbarch *gdbarch,
 		     struct type *valtype,
 		     struct regcache *regcache,
 		     gdb_byte *readbuf,
 		     const gdb_byte *writebuf)
 {
-  /* Note: Structures up to 16 bytes are returned in registers.  */
+  /* Structures up to 16 bytes are returned in registers.  */
 
   int struct_return = ((TYPE_CODE (valtype) == TYPE_CODE_STRUCT
 			|| TYPE_CODE (valtype) == TYPE_CODE_UNION
@@ -1357,8 +1537,8 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
         {
 	  struct value *arg = args[i];
 	  struct type *arg_type = check_typedef (value_type (arg));
-	  fprintf_unfiltered (gdb_stdlog, "%2d: %p %3d ",
-			      i, arg, TYPE_LENGTH (arg_type));
+	  fprintf_unfiltered (gdb_stdlog, "%2d: 0x%08x %3d ",
+			      i, (int) arg, TYPE_LENGTH (arg_type));
 	  switch (TYPE_CODE (arg_type))
 	    {
 	    case TYPE_CODE_INT:
@@ -1371,8 +1551,8 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
 	      fprintf_unfiltered (gdb_stdlog, "%3d", TYPE_CODE (arg_type));
 	      break;
 	    }
-	  fprintf_unfiltered (gdb_stdlog, " %p\n",
-			      value_contents (arg));
+	  fprintf_unfiltered (gdb_stdlog, " 0x%08x\n",
+			      (unsigned int) value_contents (arg));
 	}
     }
 
@@ -1408,7 +1588,8 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
 	      arg_type = builtin_type_long;
 	      arg = value_cast (arg_type, arg);
 	    }
-	  info->align = TYPE_LENGTH (builtin_type_long);
+	  /* Aligment is equal to the type length for the basic types.  */
+	  info->align = TYPE_LENGTH (arg_type);
 	  break;
 
 	case TYPE_CODE_FLT:
@@ -1432,7 +1613,7 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
       size = (size + info->align - 1) & ~(info->align - 1);
       onstack_size = (onstack_size + info->align - 1) & ~(info->align - 1);
 
-      if (size + info->length > REGISTER_SIZE * ARGS_NUM_REGS)
+      if (size + info->length > REGISTER_SIZE * ARG_NOF)
 	{
 	  info->onstack = 1;
 	  info->u.offset = onstack_size;
@@ -1441,7 +1622,7 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
       else
 	{
 	  info->onstack = 0;
-	  info->u.regno = ARGS_FIRST_REG + size / REGISTER_SIZE;
+	  info->u.regno = ARG_1ST + size / REGISTER_SIZE;
 	}
       size += info->length;
     }
@@ -1449,8 +1630,8 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
   /* Adjust the stack pointer and align it.  */
   sp = align_down (sp - onstack_size, SP_ALIGNMENT);
 
-  /* Simulate MOVSP.  */
-  if (sp != osp)
+  /* Simulate MOVSP, if Windowed ABI.  */
+  if ((CALL_ABI != CallAbiCall0Only) && (sp != osp))
     {
       read_memory (osp - 16, buf, 16);
       write_memory (sp - 16, buf, 16);
@@ -1461,7 +1642,7 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
   if (struct_return)
     {
       store_unsigned_integer (buf, REGISTER_SIZE, struct_addr);
-      regcache_cooked_write (regcache, ARGS_FIRST_REG, buf);
+      regcache_cooked_write (regcache, ARG_1ST, buf);
     }
 
   for (i = 0; i < nargs; i++)
@@ -1512,10 +1693,8 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
 	  else
 	    while (n > 0)
 	      {
-	        /* ULONGEST v = extract_unsigned_integer (cp, REGISTER_SIZE);*/
 		regcache_cooked_write (regcache, r, cp);
 
-		/* regcache_cooked_write_unsigned (regcache, r, v); */
 		cp += REGISTER_SIZE;
 		n -= REGISTER_SIZE;
 		r++;
@@ -1523,18 +1702,25 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
 	}
     }
 
-
   /* Set the return address of dummy frame to the dummy address.
-     Note: The return address for the current function (in A0) is
+     The return address for the current function (in A0) is
      saved in the dummy frame, so we can savely overwrite A0 here.  */
 
-  ra = (bp_addr & 0x3fffffff) | 0x40000000;
-  regcache_raw_read (regcache, gdbarch_ps_regnum (current_gdbarch), buf);
-  ps = extract_unsigned_integer (buf, 4) & ~0x00030000;
-  regcache_cooked_write_unsigned (regcache, A4_REGNUM, ra);
-  regcache_cooked_write_unsigned (regcache,
-				  gdbarch_ps_regnum (current_gdbarch),
-				  ps | 0x00010000);
+  if (CALL_ABI != CallAbiCall0Only)
+    {
+      ra = (bp_addr & 0x3fffffff) | 0x40000000;
+      regcache_raw_read (regcache, gdbarch_ps_regnum (current_gdbarch), buf);
+      ps = extract_unsigned_integer (buf, 4) & ~0x00030000;
+      regcache_cooked_write_unsigned (regcache, A4_REGNUM, ra);
+      regcache_cooked_write_unsigned (regcache,
+				      gdbarch_ps_regnum (current_gdbarch),
+				      ps | 0x00010000);
+    }
+  else
+    {
+      /* Simulate CALL0: write RA into A0 register.  */
+      regcache_cooked_write_unsigned (regcache, A0_REGNUM, bp_addr);
+    }
 
   /* Set new stack pointer and return it.  */
   regcache_cooked_write_unsigned (regcache, A1_REGNUM, sp);
@@ -1552,7 +1738,7 @@ xtensa_push_dummy_call (struct gdbarch *gdbarch,
 #define DENSITY_BIG_BREAKPOINT { 0xd2, 0x0f }
 #define DENSITY_LITTLE_BREAKPOINT { 0x2d, 0xf0 }
 
-const unsigned char *
+static const unsigned char *
 xtensa_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
 {
   static unsigned char big_breakpoint[] = BIG_BREAKPOINT;
@@ -1590,13 +1776,548 @@ xtensa_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
     }
 }
 
+/* Call0 ABI support routines.  */
+
+/* Call0 opcode class.  Opcodes are preclassified according to what they
+   mean for Call0 prologue analysis, and their number of significant operands.
+   The purpose of this is to simplify prologue analysis by separating 
+   instruction decoding (libisa) from the semantics of prologue analysis.  */
+
+typedef enum {
+  c0opc_illegal,       /* Unknown to libisa (invalid) or 'ill' opcode.  */
+  c0opc_uninteresting, /* Not interesting for Call0 prologue analysis.  */
+  c0opc_flow,	       /* Flow control insn.  */
+  c0opc_entry,	       /* ENTRY indicates non-Call0 prologue.  */
+  c0opc_break,	       /* Debugger software breakpoints.  */
+  c0opc_add,	       /* Adding two registers.  */
+  c0opc_addi,	       /* Adding a register and an immediate.  */
+  c0opc_sub,	       /* Subtracting a register from a register.  */
+  c0opc_mov,	       /* Moving a register to a register.  */
+  c0opc_movi,	       /* Moving an immediate to a register.  */
+  c0opc_l32r,	       /* Loading a literal.  */
+  c0opc_s32i,	       /* Storing word at fixed offset from a base register.  */
+  c0opc_NrOf	       /* Number of opcode classifications.  */
+} xtensa_insn_kind;
+
+
+/* Classify an opcode based on what it means for Call0 prologue analysis.  */
+
+static xtensa_insn_kind
+call0_classify_opcode (xtensa_isa isa, xtensa_opcode opc)
+{
+  const char *opcname;
+  xtensa_insn_kind opclass = c0opc_uninteresting;
+
+  DEBUGTRACE ("call0_classify_opcode (..., opc = %d)\n", opc);
+
+  /* Get opcode name and handle special classifications.  */
+
+  opcname = xtensa_opcode_name (isa, opc);
+
+  if (opcname == NULL 
+      || strcasecmp (opcname, "ill") == 0
+      || strcasecmp (opcname, "ill.n") == 0)
+    opclass = c0opc_illegal;
+  else if (strcasecmp (opcname, "break") == 0
+	   || strcasecmp (opcname, "break.n") == 0)
+     opclass = c0opc_break;
+  else if (strcasecmp (opcname, "entry") == 0)
+    opclass = c0opc_entry;
+  else if (xtensa_opcode_is_branch (isa, opc) > 0
+	   || xtensa_opcode_is_jump   (isa, opc) > 0
+	   || xtensa_opcode_is_loop   (isa, opc) > 0
+	   || xtensa_opcode_is_call   (isa, opc) > 0
+	   || strcasecmp (opcname, "simcall") == 0
+	   || strcasecmp (opcname, "syscall") == 0)
+    opclass = c0opc_flow;
+
+  /* Also, classify specific opcodes that need to be tracked.  */
+  else if (strcasecmp (opcname, "add") == 0 
+	   || strcasecmp (opcname, "add.n") == 0)
+    opclass = c0opc_add;
+  else if (strcasecmp (opcname, "addi") == 0 
+	   || strcasecmp (opcname, "addi.n") == 0
+	   || strcasecmp (opcname, "addmi") == 0)
+    opclass = c0opc_addi;
+  else if (strcasecmp (opcname, "sub") == 0)
+    opclass = c0opc_sub;
+  else if (strcasecmp (opcname, "mov.n") == 0
+	   || strcasecmp (opcname, "or") == 0) /* Could be 'mov' asm macro.  */
+    opclass = c0opc_mov;
+  else if (strcasecmp (opcname, "movi") == 0 
+	   || strcasecmp (opcname, "movi.n") == 0)
+    opclass = c0opc_movi;
+  else if (strcasecmp (opcname, "l32r") == 0)
+    opclass = c0opc_l32r;
+  else if (strcasecmp (opcname, "s32i") == 0 
+	   || strcasecmp (opcname, "s32i.n") == 0)
+    opclass = c0opc_s32i;
+
+  return opclass;
+}
+
+/* Tracks register movement/mutation for a given operation, which may
+   be within a bundle.  Updates the destination register tracking info
+   accordingly.  The pc is needed only for pc-relative load instructions
+   (eg. l32r).  The SP register number is needed to identify stores to
+   the stack frame.  */
+
+static void
+call0_track_op (xtensa_c0reg_t dst[], xtensa_c0reg_t src[],
+		xtensa_insn_kind opclass, int nods, unsigned odv[],
+		CORE_ADDR pc, int spreg)
+{
+  unsigned litbase, litaddr, litval;
+
+  switch (opclass)
+    {
+    case c0opc_addi:
+      /* 3 operands: dst, src, imm.  */
+      gdb_assert (nods == 3);
+      dst[odv[0]].fr_reg = src[odv[1]].fr_reg;
+      dst[odv[0]].fr_ofs = src[odv[1]].fr_ofs + odv[2];
+      break;
+    case c0opc_add:
+      /* 3 operands: dst, src1, src2.  */
+      gdb_assert (nods == 3);
+      if      (src[odv[1]].fr_reg == C0_CONST)
+        {
+	  dst[odv[0]].fr_reg = src[odv[2]].fr_reg;
+	  dst[odv[0]].fr_ofs = src[odv[2]].fr_ofs + src[odv[1]].fr_ofs;
+	}
+      else if (src[odv[2]].fr_reg == C0_CONST)
+        {
+	  dst[odv[0]].fr_reg = src[odv[1]].fr_reg;
+	  dst[odv[0]].fr_ofs = src[odv[1]].fr_ofs + src[odv[2]].fr_ofs;
+	}
+      else dst[odv[0]].fr_reg = C0_INEXP;
+      break;
+    case c0opc_sub:
+      /* 3 operands: dst, src1, src2.  */
+      gdb_assert (nods == 3);
+      if      (src[odv[2]].fr_reg == C0_CONST)
+        {
+	  dst[odv[0]].fr_reg = src[odv[1]].fr_reg;
+	  dst[odv[0]].fr_ofs = src[odv[1]].fr_ofs - src[odv[2]].fr_ofs;
+	}
+      else dst[odv[0]].fr_reg = C0_INEXP;
+      break;
+    case c0opc_mov:
+      /* 2 operands: dst, src [, src].  */
+      gdb_assert (nods == 2);
+      dst[odv[0]].fr_reg = src[odv[1]].fr_reg;
+      dst[odv[0]].fr_ofs = src[odv[1]].fr_ofs;
+      break;
+    case c0opc_movi:
+      /* 2 operands: dst, imm.  */
+      gdb_assert (nods == 2);
+      dst[odv[0]].fr_reg = C0_CONST;
+      dst[odv[0]].fr_ofs = odv[1];
+      break;
+    case c0opc_l32r:
+      /* 2 operands: dst, literal offset.  */
+      gdb_assert (nods == 2);
+      /* litbase = xtensa_get_litbase (pc); can be also used.  */
+      litbase = (LITBASE_REGNUM == -1)
+	? 0 : xtensa_read_register (LITBASE_REGNUM);
+      litaddr = litbase & 1
+		  ? (litbase & ~1) + (signed)odv[1]
+		  : (pc + 3  + (signed)odv[1]) & ~3;
+      litval = read_memory_integer(litaddr, 4);
+      dst[odv[0]].fr_reg = C0_CONST;
+      dst[odv[0]].fr_ofs = litval;
+      break;
+    case c0opc_s32i:
+      /* 3 operands: value, base, offset.  */
+      gdb_assert (nods == 3 && spreg >= 0 && spreg < C0_NREGS);
+      if (src[odv[1]].fr_reg == spreg	     /* Store to stack frame.  */
+	  && (src[odv[1]].fr_ofs & 3) == 0   /* Alignment preserved.  */
+	  &&  src[odv[0]].fr_reg >= 0	     /* Value is from a register.  */
+	  &&  src[odv[0]].fr_ofs == 0	     /* Value hasn't been modified.  */
+	  &&  src[src[odv[0]].fr_reg].to_stk == C0_NOSTK) /* First time.  */
+        {
+	  /* ISA encoding guarantees alignment.  But, check it anyway.  */
+	  gdb_assert ((odv[2] & 3) == 0);
+	  dst[src[odv[0]].fr_reg].to_stk = src[odv[1]].fr_ofs + odv[2];
+	}
+      break;
+    default:
+	gdb_assert (0);
+    }
+}
+
+/* Analyze prologue of the function at start address to determine if it uses 
+   the Call0 ABI, and if so track register moves and linear modifications
+   in the prologue up to the PC or just beyond the prologue, whichever is first.
+   An 'entry' instruction indicates non-Call0 ABI and the end of the prologue.
+   The prologue may overlap non-prologue instructions but is guaranteed to end
+   by the first flow-control instruction (jump, branch, call or return).
+   Since an optimized function may move information around and change the
+   stack frame arbitrarily during the prologue, the information is guaranteed
+   valid only at the point in the function indicated by the PC.
+   May be used to skip the prologue or identify the ABI, w/o tracking.
+
+   Returns:   Address of first instruction after prologue, or PC (whichever 
+	      is first), or 0, if decoding failed (in libisa).
+   Input args:
+      start   Start address of function/prologue.
+      pc      Program counter to stop at.  Use 0 to continue to end of prologue.
+	      If 0, avoids infinite run-on in corrupt code memory by bounding
+	      the scan to the end of the function if that can be determined.
+      nregs   Number of general registers to track (size of rt[] array).
+   InOut args:
+      rt[]    Array[nregs] of xtensa_c0reg structures for register tracking info.
+	      If NULL, registers are not tracked.
+   Output args:
+      call0   If != NULL, *call0 is set non-zero if Call0 ABI used, else 0
+	      (more accurately, non-zero until 'entry' insn is encountered).
+
+      Note that these may produce useful results even if decoding fails
+      because they begin with default assumptions that analysis may change.  */
+
+static CORE_ADDR
+call0_analyze_prologue (CORE_ADDR start, CORE_ADDR pc,
+			int nregs, xtensa_c0reg_t rt[], int *call0)
+{
+  CORE_ADDR ia;		    /* Current insn address in prologue.  */
+  CORE_ADDR ba = 0;	    /* Current address at base of insn buffer.  */
+  CORE_ADDR bt;		    /* Current address at top+1 of insn buffer.  */
+  #define BSZ 32	    /* Instruction buffer size.  */
+  char ibuf[BSZ];	    /* Instruction buffer for decoding prologue.  */
+  xtensa_isa isa;	    /* libisa ISA handle.  */
+  xtensa_insnbuf ins, slot; /* libisa handle to decoded insn, slot.  */
+  xtensa_format ifmt;	    /* libisa instruction format.  */
+  int ilen, islots, is;	    /* Instruction length, nbr slots, current slot.  */
+  xtensa_opcode opc;	    /* Opcode in current slot.  */
+  xtensa_insn_kind opclass; /* Opcode class for Call0 prologue analysis.  */
+  int nods;		    /* Opcode number of operands.  */
+  unsigned odv[C0_MAXOPDS]; /* Operand values in order provided by libisa.  */
+  xtensa_c0reg_t *rtmp;	    /* Register tracking info snapshot.  */
+  int j;		    /* General loop counter.  */
+  int fail = 0;		    /* Set non-zero and exit, if decoding fails.  */
+  CORE_ADDR body_pc;	    /* The PC for the first non-prologue insn.  */
+  CORE_ADDR end_pc;	    /* The PC for the lust function insn.  */
+
+  struct symtab_and_line prologue_sal;
+
+  DEBUGTRACE ("call0_analyze_prologue (start = 0x%08x, pc = 0x%08x, ...)\n", 
+	      (int)start, (int)pc);
+
+  /* Try to limit the scan to the end of the function if a non-zero pc
+     arg was not supplied to avoid probing beyond the end of valid memory.
+     If memory is full of garbage that classifies as c0opc_uninteresting.
+     If this fails (eg. if no symbols) pc ends up 0 as it was.
+     Intialize the Call0 frame and register tracking info.
+     Assume it's Call0 until an 'entry' instruction is encountered.
+     Assume we may be in the prologue until we hit a flow control instr.  */
+
+  rtmp = NULL;
+  body_pc = INT_MAX;
+  end_pc = 0;
+
+  /* Find out, if we have an information about the prologue from DWARF.  */
+  prologue_sal = find_pc_line (start, 0);
+  if (prologue_sal.line != 0) /* Found debug info.  */
+    body_pc = prologue_sal.end;
+
+  /* If we are going to analyze the prologue in general without knowing about
+     the current PC, make the best assumtion for the end of the prologue.  */
+  if (pc == 0)
+    {
+      find_pc_partial_function (start, 0, NULL, &end_pc);
+      body_pc = min (end_pc, body_pc);
+    }
+  else
+    body_pc = min (pc, body_pc);
+
+  if (call0 != NULL)
+      *call0 = 1;
+
+  if (rt != NULL)
+    {
+      rtmp = (xtensa_c0reg_t*) alloca(nregs * sizeof(xtensa_c0reg_t));
+      /* rt is already initialized in xtensa_alloc_frame_cache().  */
+    }
+  else nregs = 0;
+
+  isa = xtensa_default_isa;
+  gdb_assert (BSZ >= xtensa_isa_maxlength (isa));
+  ins = xtensa_insnbuf_alloc (isa);
+  slot = xtensa_insnbuf_alloc (isa);
+
+  for (ia = start, bt = ia; ia < body_pc ; ia += ilen)
+    {
+      /* (Re)fill instruction buffer from memory if necessary, but do not
+         read memory beyond PC to be sure we stay within text section
+	 (this protection only works if a non-zero pc is supplied).  */
+
+      if (ia + xtensa_isa_maxlength (isa) > bt)
+        {
+	  ba = ia;
+	  bt = (ba + BSZ) < body_pc ? ba + BSZ : body_pc;
+	  read_memory (ba, ibuf, bt - ba);
+	}
+
+      /* Decode format information.  */
+
+      xtensa_insnbuf_from_chars (isa, ins, &ibuf[ia-ba], 0);
+      ifmt = xtensa_format_decode (isa, ins);
+      if (ifmt == XTENSA_UNDEFINED)
+	{
+	  fail = 1;
+	  goto done;
+	}
+      ilen = xtensa_format_length (isa, ifmt);
+      if (ilen == XTENSA_UNDEFINED)
+	{
+	  fail = 1;
+	  goto done;
+	}
+      islots = xtensa_format_num_slots (isa, ifmt);
+      if (islots == XTENSA_UNDEFINED)
+	{
+	  fail = 1;
+	  goto done;
+	}
+
+      /* Analyze a bundle or a single instruction, using a snapshot of 
+         the register tracking info as input for the entire bundle so that
+	 register changes do not take effect within this bundle.  */
 
-/* Return the pc of the first real instruction.  We assume that this
-   machine uses register windows.
+      for (j = 0; j < nregs; ++j)
+	rtmp[j] = rt[j];
+
+      for (is = 0; is < islots; ++is)
+        {
+	  /* Decode a slot and classify the opcode.  */
+
+	  fail = xtensa_format_get_slot (isa, ifmt, is, ins, slot);
+	  if (fail)
+	    goto done;
+
+	  opc = xtensa_opcode_decode (isa, ifmt, is, slot);
+	  DEBUGVERB ("[call0_analyze_prologue] instr addr = 0x%08x, opc = %d\n", 
+		     (unsigned)ia, opc);
+	  if (opc == XTENSA_UNDEFINED) 
+	    opclass = c0opc_illegal;
+	  else
+	    opclass = call0_classify_opcode (isa, opc);
+
+	  /* Decide whether to track this opcode, ignore it, or bail out.  */
+
+	  switch (opclass)
+	    {
+	    case c0opc_illegal:
+	    case c0opc_break:
+	      fail = 1;
+	      goto done;
+
+	    case c0opc_uninteresting:
+	      continue;
+
+	    case c0opc_flow:
+	      goto done;
+
+	    case c0opc_entry:
+	      if (call0 != NULL)
+		*call0 = 0;
+	      ia += ilen;	       	/* Skip over 'entry' insn.  */
+	      goto done;
+
+	    default:
+	      if (call0 != NULL)
+		*call0 = 1;
+	    }
+
+	  /* Only expected opcodes should get this far.  */
+	  if (rt == NULL)
+	    continue;
+
+	  /* Extract and decode the operands.  */
+	  nods = xtensa_opcode_num_operands (isa, opc);
+	  if (nods == XTENSA_UNDEFINED)
+	    {
+	      fail = 1;
+	      goto done;
+	    }
+
+	  for (j = 0; j < nods && j < C0_MAXOPDS; ++j)
+	    {
+	      fail = xtensa_operand_get_field (isa, opc, j, ifmt, 
+					       is, slot, &odv[j]);
+	      if (fail)
+		goto done;
+
+	      fail = xtensa_operand_decode (isa, opc, j, &odv[j]);
+	      if (fail)
+		goto done;
+	    }
+
+	  /* Check operands to verify use of 'mov' assembler macro.  */
+	  if (opclass == c0opc_mov && nods == 3)
+	    {
+	      if (odv[2] == odv[1])
+		nods = 2;
+	      else
+		{
+		  opclass = c0opc_uninteresting;
+		  continue;
+		}
+	    }
+
+	  /* Track register movement and modification for this operation.  */
+	  call0_track_op (rt, rtmp, opclass, nods, odv, ia, 1);
+	}
+    }
+done:
+  DEBUGVERB ("[call0_analyze_prologue] stopped at instr addr 0x%08x, %s\n",
+	     (unsigned)ia, fail ? "failed" : "succeeded");
+  xtensa_insnbuf_free(isa, slot);
+  xtensa_insnbuf_free(isa, ins);
+  return fail ? 0 : ia;
+}
+
+/* Initialize frame cache for the current frame.  The "next_frame" is the next
+   one relative to current frame.  "cache" is the pointer to the data structure
+   we have to initialize.  "pc" is curretnt PC.  */
+
+static void
+call0_frame_cache (struct frame_info *next_frame,
+		   xtensa_frame_cache_t *cache, CORE_ADDR pc)
+{
+  CORE_ADDR start_pc;		/* The beginning of the function.  */
+  CORE_ADDR body_pc=UINT_MAX;	/* PC, where prologue analysis stopped.  */
+  CORE_ADDR sp, fp, ra;
+  int fp_regnum, c0_hasfp, c0_frmsz, prev_sp, to_stk;
+ 
+  /* Find the beginning of the prologue of the function containing the PC
+     and analyze it up to the PC or the end of the prologue.  */
+
+  if (find_pc_partial_function (pc, NULL, &start_pc, NULL))
+    {
+      body_pc = call0_analyze_prologue (start_pc, pc, C0_NREGS,
+					&cache->c0.c0_rt[0],
+					&cache->call0);
+    }
+  
+  sp = frame_unwind_register_unsigned (next_frame, A1_REGNUM);
+  fp = sp; /* Assume FP == SP until proven otherwise.  */
+
+  /* Get the frame information and FP (if used) at the current PC.
+     If PC is in the prologue, the prologue analysis is more reliable
+     than DWARF info.  We don't not know for sure if PC is in the prologue,
+     but we know no calls have yet taken place, so we can almost
+     certainly rely on the prologue analysis.  */
+
+  if (body_pc <= pc)
+    {
+      /* Prologue analysis was successful up to the PC.
+         It includes the cases when PC == START_PC.  */
+      c0_hasfp = cache->c0.c0_rt[C0_FP].fr_reg == C0_SP;
+      /* c0_hasfp == true means there is a frame pointer because
+	 we analyzed the prologue and found that cache->c0.c0_rt[C0_FP]
+	 was derived from SP.  Otherwise, it would be C0_FP.  */
+      fp_regnum = c0_hasfp ? C0_FP : C0_SP;
+      c0_frmsz = - cache->c0.c0_rt[fp_regnum].fr_ofs;
+      fp_regnum += A0_BASE;
+    }
+  else  /* No data from the prologue analysis.  */
+    {
+      c0_hasfp = 0;
+      fp_regnum = A0_BASE + C0_SP;
+      c0_frmsz = 0;
+      start_pc = pc;
+   }
+
+  prev_sp = fp + c0_frmsz;
+
+  /* Frame size from debug info or prologue tracking does not account for 
+     alloca() and other dynamic allocations.  Adjust frame size by FP - SP.  */
+  if (c0_hasfp)
+    {
+      fp = frame_unwind_register_unsigned (next_frame, fp_regnum);
+
+      /* Recalculate previous SP.  */
+      prev_sp = fp + c0_frmsz;
+      /* Update the stack frame size.  */
+      c0_frmsz += fp - sp;
+    }
+
+  /* Get the return address (RA) from the stack if saved,
+     or try to get it from a register.  */
+
+  to_stk = cache->c0.c0_rt[C0_RA].to_stk;
+  if (to_stk != C0_NOSTK)
+    ra = (CORE_ADDR) 
+      read_memory_integer (sp + c0_frmsz + cache->c0.c0_rt[C0_RA].to_stk, 4);
+
+  else if (cache->c0.c0_rt[C0_RA].fr_reg == C0_CONST
+	   && cache->c0.c0_rt[C0_RA].fr_ofs == 0)
+    {
+      /* Special case for terminating backtrace at a function that wants to
+	 be seen as the outermost.  Such a function will clear it's RA (A0)
+	 register to 0 in the prologue instead of saving its original value.  */
+      ra = 0;
+    }
+  else
+    {
+      /* RA was copied to another register or (before any function call) may
+	 still be in the original RA register.  This is not always reliable:
+	 even in a leaf function, register tracking stops after prologue, and
+	 even in prologue, non-prologue instructions (not tracked) may overwrite
+	 RA or any register it was copied to.  If likely in prologue or before
+	 any call, use retracking info and hope for the best (compiler should
+	 have saved RA in stack if not in a leaf function).  If not in prologue,
+	 too bad.  */
+
+      int i;
+      for (i = 0; 
+	   (i < C0_NREGS) &&
+	     (i == C0_RA || cache->c0.c0_rt[i].fr_reg != C0_RA);
+	   ++i);
+      if (i >= C0_NREGS && cache->c0.c0_rt[C0_RA].fr_reg == C0_RA)
+	i = C0_RA;
+      if (i < C0_NREGS) /* Read from the next_frame.  */
+	{
+	  ra = frame_unwind_register_unsigned (next_frame,
+					       A0_REGNUM + cache->c0.c0_rt[i].fr_reg);
+	}
+      else ra = 0;
+    }
+  
+  cache->pc = start_pc;
+  cache->ra = ra;
+  /* RA == 0 marks the outermost frame.  Do not go past it.  */
+  cache->prev_sp = (ra != 0) ?  prev_sp : 0;
+  cache->c0.fp_regnum = fp_regnum;
+  cache->c0.c0_frmsz = c0_frmsz;
+  cache->c0.c0_hasfp = c0_hasfp;
+  cache->c0.c0_fp = fp;
+}
+
+
+/* Skip function prologue.
+
+   Return the pc of the first instruction after prologue.  GDB calls this to
+   find the address of the first line of the function or (if there is no line
+   number information) to skip the prologue for planting breakpoints on 
+   function entries.  Use debug info (if present) or prologue analysis to skip 
+   the prologue to achieve reliable debugging behavior.  For windowed ABI, 
+   only the 'entry' instruction is skipped.  It is not strictly necessary to 
+   skip the prologue (Call0) or 'entry' (Windowed) because xt-gdb knows how to
+   backtrace at any point in the prologue, however certain potential hazards 
+   are avoided and a more "normal" debugging experience is ensured by 
+   skipping the prologue (can be disabled by defining DONT_SKIP_PROLOG).
+   For example, if we don't skip the prologue:
+   - Some args may not yet have been saved to the stack where the debug
+     info expects to find them (true anyway when only 'entry' is skipped);
+   - Software breakpoints ('break' instrs) may not have been unplanted 
+     when the prologue analysis is done on initializing the frame cache, 
+     and breaks in the prologue will throw off the analysis.
 
    If we have debug info ( line-number info, in particular ) we simply skip
    the code associated with the first function line effectively skipping
-   the prologue code. It works even in cases like
+   the prologue code.  It works even in cases like
 
    int main()
    {	int local_var = 1;
@@ -1608,41 +2329,49 @@ xtensa_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
    section to make sure there is a boundary between the prologue code and
    the rest of the function.
 
-   If there is no debug info, we need to analyze the code. */
+   If there is no debug info, we need to analyze the code.  */
+
+/* #define DONT_SKIP_PROLOGUE  */
 
 CORE_ADDR
 xtensa_skip_prologue (CORE_ADDR start_pc)
 {
+  struct symtab_and_line prologue_sal;
+  CORE_ADDR body_pc;
+
   DEBUGTRACE ("xtensa_skip_prologue (start_pc = 0x%08x)\n", (int) start_pc);
 
-  if (ISA_USE_WINDOWED_REGISTERS)
+#if DONT_SKIP_PROLOGUE
+  return start_pc;
+#endif
+
+ /* Try to find first body line from debug info.  */
+
+  prologue_sal = find_pc_line (start_pc, 0);
+  if (prologue_sal.line != 0) /* Found debug info.  */
     {
-      unsigned char op1;
-      struct symtab_and_line prologue_sal;
+      /* In Call0, it is possible to have a function with only one instruction
+	 ('ret') resulting from a 1-line optimized function that does nothing.
+	 In that case, prologue_sal.end may actually point to the start of the
+	 next function in the text section, causing a breakpoint to be set at
+	 the wrong place.  Check if the end address is in a different function,
+	 and if so return the start PC.  We know we have symbol info.  */
 
-      op1 = read_memory_integer (start_pc, 1);
-      if (!XTENSA_IS_ENTRY (op1))
+      CORE_ADDR end_func;
+
+      find_pc_partial_function (prologue_sal.end, NULL, &end_func, NULL);
+      if (end_func != start_pc)
 	return start_pc;
 
-      prologue_sal = find_pc_line (start_pc, 0);
-      if (prologue_sal.line != 0)
-	return prologue_sal.end;
-      else
-	return start_pc + XTENSA_ENTRY_LENGTH;
+      return prologue_sal.end;
     }
-  else
-    {
-      internal_error (__FILE__, __LINE__,
-		      _("non-windowed configurations are not supported"));
-      return start_pc;
-    }
-}
 
-
-/* CONFIGURATION CHECK */
+  /* No debug line info.  Analyze prologue for Call0 or simply skip ENTRY.  */
+  body_pc = call0_analyze_prologue(start_pc, 0, 0, NULL, NULL);
+  return body_pc != 0 ? body_pc : start_pc;
+}
 
 /* Verify the current configuration.  */
-
 static void
 xtensa_verify_config (struct gdbarch *gdbarch)
 {
@@ -1658,22 +2387,29 @@ xtensa_verify_config (struct gdbarch *gdbarch)
 
   /* Verify that we got a reasonable number of AREGS.  */
   if ((tdep->num_aregs & -tdep->num_aregs) != tdep->num_aregs)
-    fprintf_unfiltered (log, "\n\tnum_aregs: Number of AR registers (%d) "
-			"is not a power of two!", tdep->num_aregs);
+    fprintf_unfiltered (log, _("\
+\n\tnum_aregs: Number of AR registers (%d) is not a power of two!"),
+			tdep->num_aregs);
 
   /* Verify that certain registers exist.  */
+
   if (tdep->pc_regnum == -1)
-    fprintf_unfiltered (log, "\n\tpc_regnum: No PC register");
-  if (tdep->ps_regnum == -1)
-    fprintf_unfiltered (log, "\n\tps_regnum: No PS register");
-  if (tdep->wb_regnum == -1)
-    fprintf_unfiltered (log, "\n\twb_regnum: No WB register");
-  if (tdep->ws_regnum == -1)
-    fprintf_unfiltered (log, "\n\tws_regnum: No WS register");
-  if (tdep->ar_base == -1)
-    fprintf_unfiltered (log, "\n\tar_base: No AR registers");
+    fprintf_unfiltered (log, _("\n\tpc_regnum: No PC register"));
+  if (tdep->isa_use_exceptions && tdep->ps_regnum == -1)
+    fprintf_unfiltered (log, _("\n\tps_regnum: No PS register"));
+
+  if (tdep->isa_use_windowed_registers)
+    {
+      if (tdep->wb_regnum == -1)
+	fprintf_unfiltered (log, _("\n\twb_regnum: No WB register"));
+      if (tdep->ws_regnum == -1)
+	fprintf_unfiltered (log, _("\n\tws_regnum: No WS register"));
+      if (tdep->ar_base == -1)
+	fprintf_unfiltered (log, _("\n\tar_base: No AR registers"));
+    }
+
   if (tdep->a0_base == -1)
-    fprintf_unfiltered (log, "\n\ta0_base: No Ax registers");
+    fprintf_unfiltered (log, _("\n\ta0_base: No Ax registers"));
 
   buf = ui_file_xstrdup (log, &dummy);
   make_cleanup (xfree, buf);
@@ -1683,7 +2419,6 @@ xtensa_verify_config (struct gdbarch *gdbarch)
   do_cleanups (cleanups);
 }
 
-
 /* Module "constructor" function.  */
 
 static struct gdbarch *
@@ -1704,7 +2439,7 @@ xtensa_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   /* Verify our configuration.  */
   xtensa_verify_config (gdbarch);
 
-  /* Pseudo-Register read/write  */
+  /* Pseudo-Register read/write.  */
   set_gdbarch_pseudo_register_read (gdbarch, xtensa_pseudo_register_read);
   set_gdbarch_pseudo_register_write (gdbarch, xtensa_pseudo_register_write);
 
@@ -1770,16 +2505,12 @@ xtensa_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
   return gdbarch;
 }
 
-
-/* Dump xtensa tdep structure.  */
-
 static void
 xtensa_dump_tdep (struct gdbarch *current_gdbarch, struct ui_file *file)
 {
   error (_("xtensa_dump_tdep(): not implemented"));
 }
 
-
 void
 _initialize_xtensa_tdep (void)
 {