2011/10/12 Richard Henderson <r...@redhat.com>:
> On 10/12/2011 12:07 AM, Kai Tietz wrote:
>> Hello,
>>
>> by recent changes gcc begun to move code into the prologue region.
>> This is for x64 SEH an issue, as here the table-information for
>> prologue is limited to 255 bytes size. So we need to avoid moving
>> additional code into prologue. To achieve this we mark all standard
>> and xmm registers as prologue-used at the end of prologue. Also we
>> need to emit a memory blockage.
>>
>> ChangeLog
>>
>> 2011-10-12 Kai Tietz <kti...@redhat.com>
>>
>> * config/i386/i386.c (ix86_expand_prologue): Mark
>> for TARGET_SEH all sse/integer registers as prologue-used.
>>
>> Tested for x86_64-w64-mingw32. Ok for apply?
>>
>> Regards,
>> Kai
>>
>> Index: i386.c
>> ===================================================================
>> --- i386.c (revision 179824)
>> +++ i386.c (working copy)
>> @@ -10356,7 +10356,24 @@
>> Further, prevent alloca modifications to the stack pointer from being
>> combined with prologue modifications. */
>> if (TARGET_SEH)
>> - emit_insn (gen_prologue_use (stack_pointer_rtx));
>> + {
>> + int i;
>> +
>> + /* Due limited size of prologue-code size of 255 bytes,
>> + we need to prevent scheduler to sink instructions into
>> + prologue code. Therefore we mark all standard, sse, fpu,
>> + and the pc registers as prologue-used to prevent this.
>> + Also an memory-blockage is necessary. */
>> + emit_insn (gen_memory_blockage ());
>> +
>> + for (i = 0; i <= 7; i++)
>> + {
>> + emit_insn (gen_prologue_use (gen_rtx_REG (Pmode, AX_REG + i)));
>> + emit_insn (gen_prologue_use (gen_rtx_REG (Pmode, R8_REG + i)));
>> + emit_insn (gen_prologue_use (gen_rtx_REG (TImode, XMM0_REG + i)));
>> + emit_insn (gen_prologue_use (gen_rtx_REG (TImode, XMM8_REG + i)));
>> + }
>> + }
>
> This is overkill. We simply need to disable shrink-wrapping for SEH.
> The easiest way to do that is to add !TARGET_SEH (and a comment) to
> the simple_return pattern predicate.
>
>
> r~
Thanks, this is indeed more simple. I wasn't aware that enamed
"return_simple" expand also enables shrink-wrapping into prologue.
Patch tested for x86_64-w64-mingw32. Ok?
Regards,
Kai
Index: i386.md
===================================================================
--- i386.md (revision 179824)
+++ i386.md (working copy)
@@ -11708,9 +11708,13 @@
}
})
+;; We need to disable this for TARGET_SEH, as otherwise
+;; shrink-wrapped prologue gets enabled too. This might exceed
+;; the maximum size of prologue in unwind information.
+
(define_expand "simple_return"
[(simple_return)]
- ""
+ "!TARGET_SEH"
{
if (crtl->args.pops_args)
{
