Better support V.4 calling sequences.

1 files changed, 184 insertions, 227 deletions

diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index c3a123c..51ea307 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -177,104 +177,181 @@ single_step (signal)
 }
 
 
-/* return pc value after skipping a function prologue. */
+/* return pc value after skipping a function prologue and also return
+   information about a function frame.
 
-skip_prologue (pc)
-CORE_ADDR pc;
+   in struct rs6000_frameinfo fdata:
+    - frameless is TRUE, if function does not have a frame.
+    - nosavedpc is TRUE, if function does not save %pc value in its frame.
+    - offset is the number of bytes used in the frame to save registers.
+    - saved_gpr is the number of the first saved gpr.
+    - saved_fpr is the number of the first saved fpr.
+    - alloca_reg is the number of the register used for alloca() handling.
+      Otherwise -1.
+    - gpr_offset is the offset of the saved gprs
+    - fpr_offset is the offset of the saved fprs
+    - lr_offset is the offset of the saved lr
+    - cr_offset is the offset of the saved cr
+ */
+
+#define SIGNED_SHORT(x) 						\
+  ((sizeof (short) == 2)						\
+   ? ((int)(short)(x))							\
+   : ((int)((((x) & 0xffff) ^ 0x8000) - 0x8000)))
+
+#define GET_SRC_REG(x) (((x) >> 21) & 0x1f)
+
+CORE_ADDR
+skip_prologue (pc, fdata)
+     CORE_ADDR pc;
+     struct rs6000_framedata *fdata; 
 {
+  CORE_ADDR orig_pc = pc;
   char buf[4];
-  unsigned int tmp;
   unsigned long op;
+  int lr_reg = 0;
+  int cr_reg = 0;
+  int reg;
+  static struct rs6000_framedata zero_frame;
+
+  *fdata = zero_frame;
+  fdata->saved_gpr = -1;
+  fdata->saved_fpr = -1;
+  fdata->alloca_reg = -1;
+  fdata->frameless = 1;
+  fdata->nosavedpc = 1;
 
   if (target_read_memory (pc, buf, 4))
     return pc;			/* Can't access it -- assume no prologue. */
-  op = extract_unsigned_integer (buf, 4);
 
   /* Assume that subsequent fetches can fail with low probability.  */
+  pc -= 4;
+  for (;;)
+    {
+      pc += 4;
+      op = read_memory_integer (pc, 4);
 
-  if (op == 0x7c0802a6) {		/* mflr r0 */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-  }
-
-  if ((op & 0xfc00003e) == 0x7c000026) { /* mfcr Rx */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-  }
-
-  if ((op & 0xfc000000) == 0x48000000) { /* bl foo, to save fprs??? */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-
-    /* At this point, make sure this is not a trampoline function
-       (a function that simply calls another functions, and nothing else).
-       If the next is not a nop, this branch was part of the function
-       prologue. */
+      if ((op & 0xfc1fffff) == 0x7c0802a6) {		/* mflr Rx */
+	lr_reg = (op & 0x03e00000) | 0x90010000;
+	continue;
+
+      } else if ((op & 0xfc1fffff) == 0x7c000026) {	/* mfcr Rx */
+	cr_reg = (op & 0x03e00000) | 0x90010000;
+	continue;
+
+      } else if ((op & 0xfc1f0000) == 0xd8010000) {	/* stfd Rx,NUM(r1) */
+	reg = GET_SRC_REG (op);
+	if (fdata->saved_fpr == -1 || fdata->saved_fpr > reg) {
+	  fdata->saved_fpr = reg;
+	  fdata->fpr_offset = SIGNED_SHORT (op);
+	}
+	continue;
+
+      } else if (((op & 0xfc1f0000) == 0xbc010000) || 	/* stm Rx, NUM(r1) */
+		 ((op & 0xfc1f0000) == 0x90010000 &&	/* st rx,NUM(r1), rx >= r13 */
+		  (op & 0x03e00000) >= 0x01a00000)) {
+
+	reg = GET_SRC_REG (op);
+	if (fdata->saved_gpr == -1 || fdata->saved_gpr > reg) {
+	  fdata->saved_gpr = reg;
+	  fdata->gpr_offset = SIGNED_SHORT (op);
+	}
+	continue;
+
+      } else if ((op & 0xffff0000) == 0x3c000000) {	/* addis 0,0,NUM, used for >= 32k frames */
+	fdata->offset = (op & 0x0000ffff) << 16;
+	continue;
+
+      } else if ((op & 0xffff0000) == 0x60000000) {	/* ori 0,0,NUM, 2nd half of >= 32k frames */
+	fdata->offset |= (op & 0x0000ffff);
+	continue;
+
+      } else if ((op & 0xffff0000) == lr_reg) {		/* st Rx,NUM(r1) where Rx == lr */
+	fdata->lr_offset = SIGNED_SHORT (op);
+	fdata->nosavedpc = 0;
+	lr_reg = 0;
+	continue;
+
+      } else if ((op & 0xffff0000) == cr_reg) {		/* st Rx,NUM(r1) where Rx == cr */
+	fdata->cr_offset = SIGNED_SHORT (op);
+	cr_reg = 0;
+	continue;
+
+      } else if ((op & 0xfc000000) == 0x48000000) {	/* bl foo, to save fprs??? */
+	op = read_memory_integer (pc+4, 4);
+
+	/* At this point, make sure this is not a trampoline function
+	   (a function that simply calls another functions, and nothing else).
+	   If the next is not a nop, this branch was part of the function
+	   prologue. */
+
+	if (op == 0x4def7b82 || op == 0)		/* crorc 15, 15, 15 */
+	  return pc;					/* don't skip over this branch */
+
+	continue;
+
+      } else if ((op & 0xffff0000) == 0x94210000) {	/* stu r1,NUM(r1) */
+	fdata->offset = - SIGNED_SHORT (op);
+	pc += 4;
+	op = read_memory_integer (pc, 4);
+	break;
 
-    if (op == 0x4def7b82 ||			/* crorc 15, 15, 15 */
-	op == 0x0)
-      return pc - 4;				/* don't skip over this branch */
-  }
+      } else if (op == 0x7c21016e) {			/* stwux 1,1,0 */
+	pc += 4;					/* offset set above  */
+	op = read_memory_integer (pc, 4);
+	break;
 
-  if ((op & 0xfc1f0000) == 0xd8010000) {	/* stfd Rx,NUM(r1) */
-    pc += 4;					/* store floating register double */
-    op = read_memory_integer (pc, 4);
-  }
+      } else {
+	break;
+      }
+    }
 
-  if ((op & 0xfc1f0000) == 0xbc010000) {	/* stm Rx, NUM(r1) */
-    pc += 4;
+  /* Skip -mreloctable (V.4/eabi) load up the toc case */
+  if (op == 0x48000005 &&					/* bl .+4 */
+      read_memory_integer (pc+4, 4) == 0x7fc802a6 &&		/* mflr r30 */
+      (read_memory_integer (pc+8, 4) & 0xffff) == 0x801e0000 &&	/* lwz 0,NUM(r30) */
+      read_memory_integer (pc+12, 4) == 0x7fc0f214) {		/* add r30,r0,r30 */
+    pc += 16;
     op = read_memory_integer (pc, 4);
-  }
 
-  while ((op & 0xfc1f0000) == 0x90010000 && 	/* st rx,NUM(r1), rx >= r13 */
-	 (op & 0x03e00000) >= 0x01a00000) {
-    pc += 4;
-    op = read_memory_integer (pc, 4);
+  /* And -mminimal-toc code on V.4 */
+  } else if ((op & 0xffff0000) == 0x3fc00000 &&			/* addis 30,0,foo@ha */
+								/* addi 30,30,foo@l */
+	     ((read_memory_integer (pc+4, 4) & 0xffff0000) == 0x3bde0000)) {
+    pc += 8;
+    op = read_memory_integer (pc, 8);
   }
 
-  if (op == 0x90010008) {			/* st r0,8(r1) */
-    pc += 4;
+  while ((op >> 22) == 0x20f) {				/* l r31, ... or */
+    pc += 4;						/* l r30, ...    */
     op = read_memory_integer (pc, 4);
   }
 
-  if (op == 0x91810004) {			/* st r12,4(r1) */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-  }
-	 
-  if ((op & 0xffff0000) == 0x94210000) {	/* stu r1,NUM(r1) */
+  /* store parameters into stack */
+  while(
+	(op & 0xfc1f0000) == 0x90010000 ||		/* st rx,NUM(r1) */
+	(op & 0xfc1f0000) == 0xd8010000 ||		/* stfd Rx,NUM(r1) */
+	(op & 0xfc1f0000) == 0xfc010000) {		/* frsp, fp?,NUM(r1) */
     pc += 4;
     op = read_memory_integer (pc, 4);
   }
 
-  while ((tmp = (op >> 22)) == 0x20f) {	/* l	r31, ... or */
-    pc += 4;				/* l	r30, ...    */
-    op = read_memory_integer (pc, 4);
-  }
-
-  /* store parameters into stack */
-  while(
-	(op & 0xfc1f0000) == 0xd8010000 || 	/* stfd Rx,NUM(r1) */
-	(op & 0xfc1f0000) == 0x90010000 ||	/* st r?, NUM(r1)  */
-	(op & 0xfc000000) == 0xfc000000 ||	/* frsp, fp?, .. */
-	(op & 0xd0000000) == 0xd0000000)	/* stfs, fp?, .. */
-    {
-      pc += 4;					/* store fpr double */
-      op = read_memory_integer (pc, 4);
-    }
-
-  if (op == 0x603f0000				/* oril r31, r1, 0x0 */
-      || op == 0x7c3f0b78) {			/* mr r31, r1 */
-    pc += 4;					/* this happens if r31 is used as */
-    op = read_memory_integer (pc, 4);		/* frame ptr. (gcc does that)	  */
-
-    tmp = 0;
-    while ((op >> 16) == (0x907f + tmp)) {	/* st r3, NUM(r31) */
-      pc += 4;					/* st r4, NUM(r31), ... */
+  /* Set up frame pointer */
+  if (op == 0x603f0000					/* oril r31, r1, 0x0 */
+      || op == 0x7c3f0b78) {				/* mr r31, r1 */
+    pc += 4;						/* this happens if r31 is used as */
+    op = read_memory_integer (pc, 4);			/* frame ptr. (gcc does that)	  */
+
+    /* store parameters into frame */
+    while (
+	   (op & 0xfc1f0000) == 0x901f0000 ||		/* st rx,NUM(r1) */
+	   (op & 0xfc1f0000) == 0xd81f0000 ||		/* stfd Rx,NUM(r1) */
+	   (op & 0xfc1f0000) == 0xfc1f0000) {		/* frsp, fp?,NUM(r1) */
+      pc += 4;
       op = read_memory_integer (pc, 4);
-      tmp += 0x20;
     }
   }
+
 #if 0
 /* I have problems with skipping over __main() that I need to address
  * sometime. Previously, I used to use misc_function_vector which
@@ -302,6 +379,7 @@ CORE_ADDR pc;
   }
 #endif /* 0 */
  
+  fdata->frameless = (pc == orig_pc);
   return pc;
 }
 
@@ -496,16 +574,16 @@ pop_frame ()
      saved %pc value in the previous frame. */
 
   addr = get_pc_function_start (frame->pc) + FUNCTION_START_OFFSET;
-  function_frame_info (addr, &fdata);
+  (void) skip_prologue (addr, &fdata);
 
   if (fdata.frameless)
     prev_sp = sp;
   else
     prev_sp = read_memory_integer (sp, 4);
-  if (fdata.nosavedpc)
+  if (fdata.lr_offset == 0)
     lr = read_register (LR_REGNUM);
   else
-    lr = read_memory_integer (prev_sp+8, 4);
+    lr = read_memory_integer (prev_sp + fdata.lr_offset, 4);
 
   /* reset %pc value. */
   write_register (PC_REGNUM, lr);
@@ -568,147 +646,6 @@ fix_call_dummy(dummyname, pc, fun, nargs, type)
   *(int*)((char*)dummyname + TARGET_ADDR_OFFSET+4) = ii;
 }
 
-
-/* return information about a function frame.
-   in struct rs6000_frameinfo fdata:
-    - frameless is TRUE, if function does not have a frame.
-    - nosavedpc is TRUE, if function does not save %pc value in its frame.
-    - offset is the number of bytes used in the frame to save registers.
-    - saved_gpr is the number of the first saved gpr.
-    - saved_fpr is the number of the first saved fpr.
-    - alloca_reg is the number of the register used for alloca() handling.
-      Otherwise -1.
- */
-void
-function_frame_info (pc, fdata)
-  CORE_ADDR pc;
-  struct rs6000_framedata *fdata;
-{
-  unsigned int tmp;
-  register unsigned int op;
-  char buf[4];
-
-  fdata->offset = 0;
-  fdata->saved_gpr = fdata->saved_fpr = fdata->alloca_reg = -1;
-  fdata->frameless = 1;
-
-  /* Do not error out if we can't access the instructions.  */
-  if (target_read_memory (pc, buf, 4))
-    return;
-  op = extract_unsigned_integer (buf, 4);
-  if (op == 0x7c0802a6) {		/* mflr r0 */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-    fdata->nosavedpc = 0;
-    fdata->frameless = 0;
-  }
-  else				/* else, pc is not saved */
-    fdata->nosavedpc = 1;
-
-  if ((op & 0xfc00003e) == 0x7c000026) { /* mfcr Rx */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-    fdata->frameless = 0;
-  }
-
-  if ((op & 0xfc000000) == 0x48000000) { /* bl foo, to save fprs??? */
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-    /* At this point, make sure this is not a trampoline function
-       (a function that simply calls another functions, and nothing else).
-       If the next is not a nop, this branch was part of the function
-       prologue. */
-
-    if (op == 0x4def7b82 ||		/* crorc 15, 15, 15 */
-	op == 0x0)
-      return;				/* prologue is over */
-    fdata->frameless = 0;
-  }
-
-  if ((op & 0xfc1f0000) == 0xd8010000) { /* stfd Rx,NUM(r1) */
-    pc += 4;				 /* store floating register double */
-    op = read_memory_integer (pc, 4);
-    fdata->frameless = 0;
-  }
-
-  if ((op & 0xfc1f0000) == 0xbc010000) { /* stm Rx, NUM(r1) */
-    int tmp2;
-    fdata->saved_gpr = (op >> 21) & 0x1f;
-    tmp2 = op & 0xffff;
-    if (tmp2 > 0x7fff)
-      tmp2 = (~0 &~ 0xffff) | tmp2;
-
-    if (tmp2 < 0) {
-      tmp2 = tmp2 * -1;
-      fdata->saved_fpr = (tmp2 - ((32 - fdata->saved_gpr) * 4)) / 8;
-      if ( fdata->saved_fpr > 0)
-        fdata->saved_fpr = 32 - fdata->saved_fpr;
-      else
-        fdata->saved_fpr = -1;
-    }
-    fdata->offset = tmp2;
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-    fdata->frameless = 0;
-  }
-
-  while (((tmp = op >> 16) == 0x9001) ||	/* st   r0, NUM(r1) */
-	 (tmp == 0x9421) ||			/* stu  r1, NUM(r1) */
-	 (tmp == 0x93e1))			/* st r31, NUM(r1) */
-  {
-    int tmp2;
-
-    /* gcc takes a short cut and uses this instruction to save r31 only. */
-
-    if (tmp == 0x93e1) {
-      if (fdata->offset)
-/*        fatal ("Unrecognized prolog."); */
-        printf_unfiltered ("Unrecognized prolog!\n");
-
-      fdata->saved_gpr = 31;
-      tmp2 = op & 0xffff;
-      if (tmp2 > 0x7fff) {
-	tmp2 = - ((~0 &~ 0xffff) | tmp2);
-	fdata->saved_fpr = (tmp2 - ((32 - 31) * 4)) / 8;
-	if ( fdata->saved_fpr > 0)
-	  fdata->saved_fpr = 32 - fdata->saved_fpr;
-	else
-	  fdata->saved_fpr = -1;
-      }
-      fdata->offset = tmp2;
-    }
-    pc += 4;
-    op = read_memory_integer (pc, 4);
-    fdata->frameless = 0;
-  }
-
-  while ((tmp = (op >> 22)) == 0x20f) {	/* l	r31, ... or */
-    pc += 4;				/* l	r30, ...    */
-    op = read_memory_integer (pc, 4);
-    fdata->frameless = 0;
-  }
-
-  /* store parameters into stack */
-  while(
-	(op & 0xfc1f0000) == 0xd8010000 || 	/* stfd Rx,NUM(r1) */
-	(op & 0xfc1f0000) == 0x90010000 ||	/* st r?, NUM(r1)  */
-	(op & 0xfc000000) == 0xfc000000 ||	/* frsp, fp?, .. */
-	(op & 0xd0000000) == 0xd0000000)	/* stfs, fp?, .. */
-    {
-      pc += 4;					/* store fpr double */
-      op = read_memory_integer (pc, 4);
-      fdata->frameless = 0;
-    }
-
-  if (op == 0x603f0000				/* oril r31, r1, 0x0 */
-      || op == 0x7c3f0b78)			/* mr r31, r1 */
-    {
-      fdata->alloca_reg = 31;
-      fdata->frameless = 0;
-    }
-}
-
-
 /* Pass the arguments in either registers, or in the stack. In RS6000, the first
    eight words of the argument list (that might be less than eight parameters if
    some parameters occupy more than one word) are passed in r3..r11 registers.
@@ -964,15 +901,10 @@ CORE_ADDR pc;
 }
 
 
-/* Determines whether the function FI has a frame on the stack or not.
-   Called from the FRAMELESS_FUNCTION_INVOCATION macro in tm.h with a
-   second argument of 0, and from the FRAME_SAVED_PC macro with a
-   second argument of 1.  */
-
+/* Determines whether the function FI has a frame on the stack or not.  */
 int
-frameless_function_invocation (fi, pcsaved)
-struct frame_info *fi;
-int pcsaved;
+frameless_function_invocation (fi)
+     struct frame_info *fi;
 {
   CORE_ADDR func_start;
   struct rs6000_framedata fdata;
@@ -991,10 +923,35 @@ int pcsaved;
   if (!func_start)
     return 0;
 
-  function_frame_info (func_start, &fdata);
-  return pcsaved ? fdata.nosavedpc : fdata.frameless;
+  (void) skip_prologue (func_start, &fdata);
+  return fdata.frameless;
 }
 
+/* Return the PC saved in a frame */
+unsigned long
+frame_saved_pc (fi)
+     struct frame_info *fi;
+{
+  CORE_ADDR func_start;
+  struct rs6000_framedata fdata;
+  int frameless;
+
+  func_start = get_pc_function_start (fi->pc) + FUNCTION_START_OFFSET;
+
+  /* If we failed to find the start of the function, it is a mistake
+     to inspect the instructions. */
+  if (!func_start)
+    return 0;
+
+  (void) skip_prologue (func_start, &fdata);
+  if (fdata.lr_offset == 0)
+    return read_register (LR_REGNUM);
+
+  if (fi->signal_handler_caller)
+    return read_memory_integer (fi->frame + SIG_FRAME_PC_OFFSET, 4);
+
+  return read_memory_integer (rs6000_frame_chain (fi) + fdata.lr_offset, 4);
+}
 
 /* If saved registers of frame FI are not known yet, read and cache them.
    &FDATAP contains rs6000_framedata; TDATAP can be NULL,
@@ -1014,7 +971,7 @@ frame_get_cache_fsr (fi, fdatap)
   
   if (fdatap == NULL) {
     fdatap = &work_fdata;
-    function_frame_info (get_pc_function_start (fi->pc), fdatap);
+    (void) skip_prologue (get_pc_function_start (fi->pc), fdatap);
   }
 
   fi->cache_fsr = (struct frame_saved_regs *)
@@ -1065,7 +1022,7 @@ frame_initial_stack_address (fi)
 
   /* find out if this function is using an alloca register.. */
 
-  function_frame_info (get_pc_function_start (fi->pc), &fdata);
+  (void) skip_prologue (get_pc_function_start (fi->pc), &fdata);
 
   /* if saved registers of this frame are not known yet, read and cache them. */