https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69454
--- Comment #4 from Ilya Enkovich <ienkovich at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #3)
> I need additional -march=x86-64 to trigger this.
> I'd say either we have to pessimistically assume what the STV pass might be
> doing already during expansion, or the STV pass would need to perform parts
> of what expand_stack_alignment is doing (basically check if what the STV
> pass created causes any differences in decision during
> expand_stack_alignment, and if yes, tweak things so that the end result
> looks as if those decisions were done already during the expansion (STV is
> pre-RA pass, so maybe it still could work), or maybe easiest fix is for now
> disable TARGET_STV if preferred_stack_boundary is smaller than 4.
Looking into expand_stack_alignment I see we may need to allocate DRAP register
and make fixup_tail_calls call. Isn't it too late for that? Couldn't we make
some optimizations basing on notes fixup_tail_calls invalidates?
I propose this change in STV gate:
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 34b57a4..fb11680 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -3661,7 +3661,11 @@ public:
/* opt_pass methods: */
virtual bool gate (function *)
{
- return !TARGET_64BIT && TARGET_STV && TARGET_SSE2 && optimize > 1;
+ return !TARGET_64BIT && TARGET_STV && TARGET_SSE2 && optimize > 1
+ /* Check we don't need to allocate DRAP register for STV. */
+ && (crtl->drap_reg
+ || !crtl->need_drap
+ || INCOMING_STACK_BOUNDARY >= 128);
}
virtual unsigned int execute (function *)
