[mc] Implement translation of register number

Libunwind and DWARF do not associated the same regsiter number (at
least in i386) so me need to translate from DWARf register numbers
into libunwind register numbers.

Fix broken expression evaluation on i386.

diff --git a/src/mc/mc_dwarf_expression.c b/src/mc/mc_dwarf_expression.c
index f143a37..d854c6e 100644 (file)
--- a/src/mc/mc_dwarf_expression.c
+++ b/src/mc/mc_dwarf_expression.c
@@ -20,6 +20,45 @@ static int mc_dwarf_push_value(mc_expression_state_t state, Dwarf_Off value) {
   return 0;
 }
 
+static int mc_dwarf_register_to_libunwind(int dwarf_register) {
+  #if defined(UNW_TARGET_X86_64)
+  // It seems for this arch, DWARF and libunwind agree in the numbering:
+  return dwarf_register;
+  #elif defined(UNW_TARGET_X86)
+  // Could't find the authoritative source of information for this.
+  // This is inspired from http://source.winehq.org/source/dlls/dbghelp/cpu_i386.c#L517.
+  switch(dwarf_register) {
+  case 0:  return UNW_X86_EAX;
+  case 1:  return UNW_X86_ECX;
+  case 2:  return UNW_X86_EDX;
+  case 3:  return UNW_X86_EBX;
+  case 4:  return UNW_X86_ESP;
+  case 5:  return UNW_X86_EBP;
+  case 6:  return UNW_X86_ESI;
+  case 7:  return UNW_X86_EDI;
+  case 8:  return UNW_X86_EIP;
+  case 9:  return UNW_X86_EFLAGS;
+  case 10: return UNW_X86_CS;
+  case 11: return UNW_X86_SS;
+  case 12: return UNW_X86_DS;
+  case 13: return UNW_X86_ES;
+  case 14: return UNW_X86_FS;
+  case 15: return UNW_X86_GS;
+  case 16: return UNW_X86_ST0;
+  case 17: return UNW_X86_ST1;
+  case 18: return UNW_X86_ST2;
+  case 19: return UNW_X86_ST3;
+  case 10: return UNW_X86_ST4;
+  case 21: return UNW_X86_ST5;
+  case 22: return UNW_X86_ST6;
+  case 23: return UNW_X86_ST7;
+  default: xbt_die("BAd/unknown register number.");
+  }
+  #else
+  #error This architecture is not supported yet.
+  #endif
+}
+
 int mc_dwarf_execute_expression(
   size_t n, const Dwarf_Op* ops, mc_expression_state_t state) {
   for(int i=0; i!=n; ++i) {
@@ -39,7 +78,7 @@ int mc_dwarf_execute_expression(
     case DW_OP_breg20: case DW_OP_breg21: case DW_OP_breg22: case DW_OP_breg23:
     case DW_OP_breg24: case DW_OP_breg25: case DW_OP_breg26: case DW_OP_breg27:
     case DW_OP_breg28: case DW_OP_breg29: case DW_OP_breg30: case DW_OP_breg31:{
-        int register_id = op->atom - DW_OP_breg0;
+        int register_id = mc_dwarf_register_to_libunwind(op->atom - DW_OP_breg0);
         unw_word_t res;
         if(!state->cursor)
           return MC_EXPRESSION_E_MISSING_STACK_CONTEXT;