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Diffstat (limited to 'gdb/i386-tdep.c')
-rw-r--r--gdb/i386-tdep.c56
1 files changed, 53 insertions, 3 deletions
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 1ef1bb8..036d1b6 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -308,6 +308,7 @@ struct i386_frame_cache
/* Saved registers. */
CORE_ADDR saved_regs[I386_NUM_SAVED_REGS];
CORE_ADDR saved_sp;
+ int stack_align;
int pc_in_eax;
/* Stack space reserved for local variables. */
@@ -334,6 +335,7 @@ i386_alloc_frame_cache (void)
for (i = 0; i < I386_NUM_SAVED_REGS; i++)
cache->saved_regs[i] = -1;
cache->saved_sp = 0;
+ cache->stack_align = 0;
cache->pc_in_eax = 0;
/* Frameless until proven otherwise. */
@@ -485,6 +487,33 @@ i386_skip_probe (CORE_ADDR pc)
return pc;
}
+/* GCC 4.1 and later, can put code in the prologue to realign the
+ stack pointer. Check whether PC points to such code, and update
+ CACHE accordingly. Return the first instruction after the code
+ sequence or CURRENT_PC, whichever is smaller. If we don't
+ recognize the code, return PC. */
+
+static CORE_ADDR
+i386_analyze_stack_align (CORE_ADDR pc, CORE_ADDR current_pc,
+ struct i386_frame_cache *cache)
+{
+ static const gdb_byte insns[10] = {
+ 0x8d, 0x4c, 0x24, 0x04, /* leal 4(%esp), %ecx */
+ 0x83, 0xe4, 0xf0, /* andl $-16, %esp */
+ 0xff, 0x71, 0xfc /* pushl -4(%ecx) */
+ };
+ gdb_byte buf[10];
+
+ if (target_read_memory (pc, buf, sizeof buf)
+ || memcmp (buf, insns, sizeof buf) != 0)
+ return pc;
+
+ if (current_pc > pc + 4)
+ cache->stack_align = 1;
+
+ return min (pc + 10, current_pc);
+}
+
/* Maximum instruction length we need to handle. */
#define I386_MAX_INSN_LEN 6
@@ -777,6 +806,7 @@ i386_analyze_prologue (CORE_ADDR pc, CORE_ADDR current_pc,
pc = i386_follow_jump (pc);
pc = i386_analyze_struct_return (pc, current_pc, cache);
pc = i386_skip_probe (pc);
+ pc = i386_analyze_stack_align (pc, current_pc, cache);
pc = i386_analyze_frame_setup (pc, current_pc, cache);
return i386_analyze_register_saves (pc, current_pc, cache);
}
@@ -907,6 +937,13 @@ i386_frame_cache (struct frame_info *next_frame, void **this_cache)
if (cache->pc != 0)
i386_analyze_prologue (cache->pc, frame_pc_unwind (next_frame), cache);
+ if (cache->stack_align)
+ {
+ /* Saved stack pointer has been saved in %ecx. */
+ frame_unwind_register (next_frame, I386_ECX_REGNUM, buf);
+ cache->saved_sp = extract_unsigned_integer(buf, 4);
+ }
+
if (cache->locals < 0)
{
/* We didn't find a valid frame, which means that CACHE->base
@@ -917,13 +954,26 @@ i386_frame_cache (struct frame_info *next_frame, void **this_cache)
frame by looking at the stack pointer. For truly "frameless"
functions this might work too. */
- frame_unwind_register (next_frame, I386_ESP_REGNUM, buf);
- cache->base = extract_unsigned_integer (buf, 4) + cache->sp_offset;
+ if (cache->stack_align)
+ {
+ /* We're halfway aligning the stack. */
+ cache->base = ((cache->saved_sp - 4) & 0xfffffff0) - 4;
+ cache->saved_regs[I386_EIP_REGNUM] = cache->saved_sp - 4;
+
+ /* This will be added back below. */
+ cache->saved_regs[I386_EIP_REGNUM] -= cache->base;
+ }
+ else
+ {
+ frame_unwind_register (next_frame, I386_ESP_REGNUM, buf);
+ cache->base = extract_unsigned_integer (buf, 4) + cache->sp_offset;
+ }
}
/* Now that we have the base address for the stack frame we can
calculate the value of %esp in the calling frame. */
- cache->saved_sp = cache->base + 8;
+ if (cache->saved_sp == 0)
+ cache->saved_sp = cache->base + 8;
/* Adjust all the saved registers such that they contain addresses
instead of offsets. */