On Thu, May 27, 2021 at 7:03 AM Hongtao Liu <[email protected]> wrote:
>
> Hi:
> This is an updated patch which implements vzeroupper as call_insn
> which has a special vzeroupper ABI, also in this patch i reverted
> r11-7684, r10-6451, r10-3677 which seems to fix the same issue but in
> a different way.
> Bootstrapped and regtested on x86_64-linux-gnux{-m32,} and
> x86_64-linux-gnux{-m32 \-march=cascadelake,-march=cascadelake}.
> Also test the patch on SPEC2017 and eembc, no performance impact as
> expected.
> Ok for trunk?
>
> gcc/ChangeLog:
>
> PR target/82735
> * config/i386/i386-expand.c (ix86_expand_builtin): Remove
> assignment of cfun->machine->has_explicit_vzeroupper.
> * config/i386/i386-features.c
> (ix86_add_reg_usage_to_vzerouppers): Delete.
> (ix86_add_reg_usage_to_vzeroupper): Ditto.
> (rest_of_handle_insert_vzeroupper): Remove
> ix86_add_reg_usage_to_vzerouppers, add df_analyze at the end
> of the function.
> (gate): Remove cfun->machine->has_explicit_vzeroupper.
> * config/i386/i386-protos.h (ix86_expand_avx_vzeroupper):
> Declared.
> * config/i386/i386.c (ix86_insn_callee_abi): New function.
> (ix86_initialize_callee_abi): Ditto.
> (ix86_expand_avx_vzeroupper): Ditto.
> (ix86_hard_regno_call_part_clobbered): Adjust for vzeroupper
> ABI.
> (TARGET_INSN_CALLEE_ABI): Define as ix86_insn_callee_abi.
> * config/i386/i386.h (enum i386_insn_callee_abi_index): New.
> (struct GTY(()) machine_function): Delete
> has_explicit_vzeroupper.
> * config/i386/i386.md (enum unspec): New member
> UNSPEC_CALLEE_ABI.
> * config/i386/predicates.md (vzeroupper_pattern): Adjust.
> * config/i386/sse.md (avx_vzeroupper): Call
> ix86_expand_avx_vzeroupper.
> (*avx_vzeroupper): Rename to ..
> (avx_vzeroupper_callee_abi): .. this, and adjust pattern as
> call_insn which has a special vzeroupper ABI.
> (*avx_vzeroupper_1): Deleted.
> * df-scan.c (df_get_call_refs): When call_insn is a fake call,
> it won't use stack pointer reg.
> * final.c (leaf_function_p): When call_insn is a fake call, it
> won't affect caller as a leaf function.
> * reg-stack.c (callee_clobbers_any_stack_reg): New.
> (subst_stack_regs): When call_insn doesn't clobber any stack
> reg, don't clear the arguments.
> * rtl.c (shallow_copy_rtx): Don't clear flag used when orig is
> a insn.
> * shrink-wrap.c (requires_stack_frame_p): No need for stack
> frame for a fake call.
>
> gcc/testsuite/ChangeLog:
>
> PR target/82735
> * gcc.target/i386/pr82735-1.c: New test.
> * gcc.target/i386/pr82735-2.c: New test.
> * gcc.target/i386/pr82735-3.c: New test.
> * gcc.target/i386/pr82735-4.c: New test.
> * gcc.target/i386/pr82735-5.c: New test.
Please split the patch to middle-end and target part. The middle-end
should be approved first.
(define_expand "avx_vzeroupper"
- [(parallel [(unspec_volatile [(const_int 0)] UNSPECV_VZEROUPPER)])]
- "TARGET_AVX")
+ [(parallel [(call (mem:QI (unspec_volatile [(const_int 0)]
UNSPECV_VZEROUPPER))
+ (const_int 0))
+ (unspec [(const_int 1)] UNSPEC_CALLEE_ABI)])]
The call insn doesn't look like a valid RTX. Why not just:
+ [(parallel [(call (mem:QI (const_int 0)
+ (const_int 0))
for a fake call? Also, UNSPEC_VZEROUPPER can be removed this way since
the const_int 1 of UNSPEC_CALLEE_ABI is now used to detect vzeroupper.
Also, you don't need the avx_vzeroupper pattern to just call
ix86_expand_avx_vzeroupper. Just call the function directly from the
call site:
case AVX_U128:
if (mode == AVX_U128_CLEAN)
emit_insn (gen_avx_vzeroupper ());
break;
+ (unspec [(const_int 1)] UNSPEC_CALLEE_ABI)])]
Can this const_int 1 be somehow more descriptive? Perhaps use
define_constant to define I386_VZEROUPPER ABI and use it in .md as
well as .c files.
Uros.
