* mips-tdep.c (mips_skip_prologue): Always skip the typical prologue

	instructions and nothing more.
	* mipsread.c (add_line): Add comment why we have to combine line number
	entries for the same line number.

3 files changed, 64 insertions, 17 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9c4f124..1f00f54 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+Fri Apr 16 12:27:11 1993  Peter Schauer  (pes@regent.e-technik.tu-muenchen.de)
+
+	* mips-tdep.c (mips_skip_prologue): Always skip the typical prologue
+	instructions and nothing more.
+	* mipsread.c (add_line): Add comment why we have to combine line number
+	entries for the same line number.
+
 Fri Apr 16 09:42:03 1993  Jim Kingdon  (kingdon@cygnus.com)
 
 	* symtab.{c,h}: Doc fixes (remove symseg references, last relevant
diff --git a/gdb/mips-tdep.c b/gdb/mips-tdep.c
index d68fbc29..14267fa 100644
--- a/gdb/mips-tdep.c
+++ b/gdb/mips-tdep.c
@@ -87,17 +87,18 @@ read_next_frame_reg(fi, regno)
      FRAME fi;
      int regno;
 {
-#define SIGFRAME_BASE   sizeof(struct sigcontext)
-#define SIGFRAME_PC_OFF (-SIGFRAME_BASE+ 2*sizeof(int))
-#define SIGFRAME_SP_OFF (-SIGFRAME_BASE+32*sizeof(int))
-#define SIGFRAME_RA_OFF (-SIGFRAME_BASE+34*sizeof(int))
+  /* If it is the frame for sigtramp we have a complete sigcontext
+     immediately below the frame and we get the saved registers from there.
+     If the stack layout for sigtramp changes we might have to change these
+     constants and the companion fixup_sigtramp in mipsread.c  */
+#define SIGFRAME_BASE		0x12c	/* sizeof(sigcontext) */
+#define SIGFRAME_PC_OFF		(-SIGFRAME_BASE + 2 * 4)
+#define SIGFRAME_REGSAVE_OFF	(-SIGFRAME_BASE + 3 * 4)
   for (; fi; fi = fi->next)
       if (in_sigtramp(fi->pc, 0)) {
-	  /* No idea if this code works. --PB. */
 	  int offset;
 	  if (regno == PC_REGNUM) offset = SIGFRAME_PC_OFF;
-	  else if (regno == RA_REGNUM) offset = SIGFRAME_RA_OFF;
-	  else if (regno == SP_REGNUM) offset = SIGFRAME_SP_OFF;
+	  else if (regno < 32) offset = SIGFRAME_REGSAVE_OFF + regno * 4;
 	  else return 0;
 	  return read_memory_integer(fi->frame + offset, 4);
       }
@@ -728,19 +729,32 @@ mips_skip_prologue(pc)
     int offset;
     int seen_sp_adjust = 0;
 
-    /* For -g modules and most functions anyways the
-       first instruction adjusts the stack.
-       But we allow some number of stores before the stack adjustment.
-       (These are emitted by varags functions compiled by gcc-2.0. */
+    /* Skip the typical prologue instructions. These are the stack adjustment
+       instruction and the instructions that save registers on the stack
+       or in the gcc frame.  */
     for (offset = 0; offset < 100; offset += 4) {
 	inst = read_memory_integer(pc + offset, 4);
-	if ((inst & 0xffff0000) == 0x27bd0000) /* addiu $sp,$sp,offset */
+	if ((inst & 0xffff0000) == 0x27bd0000)	/* addiu $sp,$sp,offset */
 	    seen_sp_adjust = 1;
-	else if ((inst & 0xFFE00000) == 0xAFA00000) /* sw reg,n($sp) */
+	else if ((inst & 0xFFE00000) == 0xAFA00000 && (inst & 0x001F0000))
+	    continue;				/* sw reg,n($sp) */
+						/* reg != $zero */
+	else if ((inst & 0xFFE00000) == 0xE7A00000) /* swc1 freg,n($sp) */
+	    continue;
+	else if ((inst & 0xF3E00000) == 0xA3C00000 && (inst & 0x001F0000))
+						/* sx reg,n($s8) */
+	    continue;				/* reg != $zero */
+	else if (inst == 0x03A0F021)		/* move $s8,$sp */
 	    continue;
 	else
-	  break;
+	    break;
     }
+    return pc + offset;
+
+/* FIXME schauer. The following code seems no longer necessary if we
+   always skip the typical prologue instructions.  */
+
+#if 0
     if (seen_sp_adjust)
       return pc + offset;
 
@@ -764,6 +778,7 @@ mips_skip_prologue(pc)
 	return pc + 4;
 
     return pc;
+#endif
 }
 
 /* Let the user turn off floating point.  */
diff --git a/gdb/mipsread.c b/gdb/mipsread.c
index b6523e1..4f0558b 100644
--- a/gdb/mipsread.c
+++ b/gdb/mipsread.c
@@ -180,6 +180,9 @@ struct complaint pdr_for_nonsymbol_complaint =
 struct complaint pdr_static_symbol_complaint =
 {"can't handle PDR for static proc at 0x%x", 0, 0};
 
+struct complaint bad_setjmp_pdr_complaint =
+{"fixing bad setjmp PDR from libc", 0, 0};
+
 /* Macros and extra defs */
 
 /* Already-parsed symbols are marked specially */
@@ -1583,6 +1586,16 @@ parse_procedure (pr, have_stabs, first_off)
       e->pdr = *pr;
       e->pdr.isym = (long) s;
       e->pdr.adr += cur_fdr->adr - first_off;
+
+      /* Correct incorrect setjmp procedure descriptor from the library
+	 to make backtrace through setjmp work.  */
+      if (e->pdr.pcreg == 0 && strcmp (sh_name, "setjmp") == 0)
+	{
+	  complain (&bad_setjmp_pdr_complaint, 0);
+	  e->pdr.pcreg = RA_REGNUM;
+	  e->pdr.regmask = 0x80000000;
+	  e->pdr.regoffset = -4;
+	}
     }
 }
 
@@ -2824,7 +2837,18 @@ add_block (b, s)
 
 /* Add a new linenumber entry (LINENO,ADR) to a linevector LT.
    MIPS' linenumber encoding might need more than one byte
-   to describe it, LAST is used to detect these continuation lines */
+   to describe it, LAST is used to detect these continuation lines.
+
+   Combining lines with the same line number seems like a bad idea.
+   E.g: There could be a line number entry with the same line number after the
+   prologue and GDB should not ignore it (this is a better way to find
+   a prologue than mips_skip_prologue).
+   But due to the compressed line table format there are line number entries
+   for the same line which are needed to bridge the gap to the next
+   line number entry. These entries have a bogus address info with them
+   and we are unable to tell them from intended duplicate line number
+   entries.
+   This is another reason why -ggdb debugging format is preferable.  */
 
 static int
 add_line (lt, lineno, adr, last)
@@ -3170,11 +3194,12 @@ fixup_sigtramp ()
     /* align_longword(sigcontext + SIGFRAME) */
     e->pdr.frameoffset = 0x150;
     e->pdr.framereg = SP_REGNUM;
-    e->pdr.pcreg = 31;
+    /* read_next_frame_reg provides the true pc at the time of signal */
+    e->pdr.pcreg = PC_REGNUM;
     e->pdr.regmask = -2;
     e->pdr.regoffset = -(41 * sizeof (int));
     e->pdr.fregmask = -1;
-    e->pdr.fregoffset = -(37 * sizeof (int));
+    e->pdr.fregoffset = -(7 * sizeof (int));
     e->pdr.isym = (long) s;
 
     current_objfile = st->objfile;	/* Keep new_symbol happy */