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~
