[FT32] gdb: Correctly interpret function prologs

The stack unwinder did not understand the function prologs
generated by gcc with -Os. Add code to recognize and interpret the
prolog calls.

[gdb]

2015-10-02  James Bowman  <james.bowman@ftdichip.com>

	* ft32-tdep.c (ft32_analyze_prologue): Add function prolog
	subroutine handling.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f9ef565634818d8c07c505984268d614a75c0f77..20d4a4b425f4ca341bc4ba9a1f71d21d40576bee 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2015-10-02  James Bowman  <james.bowman@ftdichip.com>
+
+       * ft32-tdep.c (ft32_analyze_prologue): Add function prolog
+       subroutine handling.
+
 2015-10-01  Simon Marchi  <simon.marchi@ericsson.com>
 
        * common/vec.h (VEC_OP (T,cleanup)): Add pointer cast.

diff --git a/gdb/ft32-tdep.c b/gdb/ft32-tdep.c
index 00cf847f76200b5561940fad3a09753f57a1b397..e9da23ec9d3c681f36f50c7983134a753b272052 100644 (file)
--- a/gdb/ft32-tdep.c
+++ b/gdb/ft32-tdep.c
@@ -164,33 +164,76 @@ ft32_analyze_prologue (CORE_ADDR start_addr, CORE_ADDR end_addr,
   CORE_ADDR next_addr;
   ULONGEST inst, inst2;
   LONGEST offset;
-  int regnum;
+  int regnum, pushreg;
+  struct bound_minimal_symbol msymbol;
+  const int first_saved_reg = 13;      /* The first saved register.  */
+  /* PROLOGS are addresses of the subroutine prologs, PROLOGS[n]
+     is the address of __prolog_$rN.
+     __prolog_$rN pushes registers from 13 through n inclusive.
+     So for example CALL __prolog_$r15 is equivalent to:
+       PUSH $r13 
+       PUSH $r14 
+       PUSH $r15 
+     Note that PROLOGS[0] through PROLOGS[12] are unused.  */
+  CORE_ADDR prologs[32];
 
   cache->saved_regs[FT32_PC_REGNUM] = 0;
   cache->framesize = 0;
 
+  for (regnum = first_saved_reg; regnum < 32; regnum++)
+    {
+      char prolog_symbol[32];
+
+      snprintf (prolog_symbol, sizeof (prolog_symbol), "__prolog_$r%02d",
+               regnum);
+      msymbol = lookup_minimal_symbol (prolog_symbol, NULL, NULL);
+      if (msymbol.minsym)
+       prologs[regnum] = BMSYMBOL_VALUE_ADDRESS (msymbol);
+      else
+       prologs[regnum] = 0;
+    }
+
   if (start_addr >= end_addr)
-      return end_addr;
+    return end_addr;
 
   cache->established = 0;
-  for (next_addr = start_addr; next_addr < end_addr; )
+  for (next_addr = start_addr; next_addr < end_addr;)
     {
       inst = read_memory_unsigned_integer (next_addr, 4, byte_order);
 
       if (FT32_IS_PUSH (inst))
        {
-         regnum = FT32_R0_REGNUM + FT32_PUSH_REG (inst);
+         pushreg = FT32_PUSH_REG (inst);
          cache->framesize += 4;
-         cache->saved_regs[regnum] = cache->framesize;
+         cache->saved_regs[FT32_R0_REGNUM + pushreg] = cache->framesize;
          next_addr += 4;
        }
+      else if (FT32_IS_CALL (inst))
+       {
+         for (regnum = first_saved_reg; regnum < 32; regnum++)
+           {
+             if ((4 * (inst & 0x3ffff)) == prologs[regnum])
+               {
+                 for (pushreg = first_saved_reg; pushreg <= regnum;
+                      pushreg++)
+                   {
+                     cache->framesize += 4;
+                     cache->saved_regs[FT32_R0_REGNUM + pushreg] =
+                       cache->framesize;
+                   }
+                 next_addr += 4;
+               }
+           }
+         break;
+       }
       else
        break;
     }
   for (regnum = FT32_R0_REGNUM; regnum < FT32_PC_REGNUM; regnum++)
     {
       if (cache->saved_regs[regnum] != REG_UNAVAIL)
-       cache->saved_regs[regnum] = cache->framesize - cache->saved_regs[regnum];
+       cache->saved_regs[regnum] =
+         cache->framesize - cache->saved_regs[regnum];
     }
   cache->saved_regs[FT32_PC_REGNUM] = cache->framesize;