Bootstrapped and regtested on x86_64-redhat-linux. Ok for master?
The FakeStack flag is not zeroed out when can_store_by_pieces()
returns false. Over time, this causes FakeStack::Allocate() to perform
the maximum number of loop iterations, significantly slowing down the
instrumented program.
gcc/ChangeLog:
* asan.cc (asan_emit_stack_protection): Always zero the flag
unless it is cleared by the __asan_stack_free_N() libcall.
Signed-off-by: Ilya Leoshkevich <[email protected]>
---
gcc/asan.cc | 30 ++++++++++++++++++------------
1 file changed, 18 insertions(+), 12 deletions(-)
diff --git a/gcc/asan.cc b/gcc/asan.cc
index 452a5a33327..da21d5e1008 100644
--- a/gcc/asan.cc
+++ b/gcc/asan.cc
@@ -2167,27 +2167,16 @@ asan_emit_stack_protection (rtx base, rtx pbase,
unsigned int alignb,
mem = adjust_address (mem, VOIDmode, base_align_bias);
emit_move_insn (mem, gen_int_mode (ASAN_STACK_RETIRED_MAGIC, ptr_mode));
unsigned HOST_WIDE_INT sz = asan_frame_size >> ASAN_SHADOW_SHIFT;
+ bool asan_stack_free_emitted_p = false;
if (use_after_return_class < 5
&& can_store_by_pieces (sz, builtin_memset_read_str, &c,
BITS_PER_UNIT, true))
{
/* Emit:
memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
- **SavedFlagPtr(FakeStack, class_id) = 0
*/
store_by_pieces (shadow_mem, sz, builtin_memset_read_str, &c,
BITS_PER_UNIT, true, RETURN_BEGIN);
-
- unsigned HOST_WIDE_INT offset
- = (1 << (use_after_return_class + 6));
- offset -= GET_MODE_SIZE (ptr_mode);
- mem = gen_rtx_MEM (ptr_mode, base);
- mem = adjust_address (mem, ptr_mode, offset);
- rtx addr = gen_reg_rtx (ptr_mode);
- emit_move_insn (addr, mem);
- addr = convert_memory_address (Pmode, addr);
- mem = gen_rtx_MEM (QImode, addr);
- emit_move_insn (mem, const0_rtx);
}
else if (use_after_return_class >= 5
|| !set_storage_via_setmem (shadow_mem,
@@ -2205,6 +2194,23 @@ asan_emit_stack_protection (rtx base, rtx pbase,
unsigned int alignb,
GEN_INT (asan_frame_size + base_align_bias),
TYPE_MODE (pointer_sized_int_node),
orig_addr, ptr_mode);
+ asan_stack_free_emitted_p = true;
+ }
+ if (!asan_stack_free_emitted_p)
+ {
+ /* Emit:
+ **SavedFlagPtr (FakeStack, class_id) = 0
+ */
+ unsigned HOST_WIDE_INT offset
+ = (1 << (use_after_return_class + 6));
+ offset -= GET_MODE_SIZE (ptr_mode);
+ mem = gen_rtx_MEM (ptr_mode, base);
+ mem = adjust_address (mem, ptr_mode, offset);
+ rtx addr = gen_reg_rtx (ptr_mode);
+ emit_move_insn (addr, mem);
+ addr = convert_memory_address (Pmode, addr);
+ mem = gen_rtx_MEM (QImode, addr);
+ emit_move_insn (mem, const0_rtx);
}
lab = gen_label_rtx ();
emit_jump (lab);
--
2.47.1
