[DAGCombiner] Remove NoSignedZerosFPMath uses in visitFSUB

[paperchalice]

Remove NoSignedZerosFPMath in visitFSUB part, we should always use instruction level fast math flags.

[llvmbot]

@llvm/pr-subscribers-backend-x86

@llvm/pr-subscribers-backend-amdgpu

Author: None (paperchalice)

Changes

Remove NoSignedZerosFPMath in visitFSUB part, we should always use instruction level fast math flags.

---

Full diff: https://github.com/llvm/llvm-project/pull/160974.diff

4 Files Affected:

• (modified) llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (+3-6)
• (modified) llvm/test/CodeGen/AMDGPU/fneg-combines.new.ll (+22-7)
• (modified) llvm/test/CodeGen/X86/negative-sin.ll (+5-10)
• (modified) llvm/test/CodeGen/X86/vec_unsafe-fp-math.ll (+2-2)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c81568672de3c..77df4b4598c48 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -17983,8 +17983,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   // (fsub A, 0) -> A
   if (N1CFP && N1CFP->isZero()) {
-    if (!N1CFP->isNegative() || Options.NoSignedZerosFPMath ||
-        Flags.hasNoSignedZeros()) {
+    if (!N1CFP->isNegative() || Flags.hasNoSignedZeros()) {
       return N0;
     }
   }
@@ -17997,8 +17996,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   // (fsub -0.0, N1) -> -N1
   if (N0CFP && N0CFP->isZero()) {
-    if (N0CFP->isNegative() ||
-        (Options.NoSignedZerosFPMath || Flags.hasNoSignedZeros())) {
+    if (N0CFP->isNegative() || Flags.hasNoSignedZeros()) {
       // We cannot replace an FSUB(+-0.0,X) with FNEG(X) when denormals are
       // flushed to zero, unless all users treat denorms as zero (DAZ).
       // FIXME: This transform will change the sign of a NaN and the behavior
@@ -18014,8 +18012,7 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) {
     }
   }
 
-  if ((Options.NoSignedZerosFPMath ||
-       (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
+  if (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros() &&
       N1.getOpcode() == ISD::FADD) {
     // X - (X + Y) -> -Y
     if (N0 == N1->getOperand(0))
diff --git a/llvm/test/CodeGen/AMDGPU/fneg-combines.new.ll b/llvm/test/CodeGen/AMDGPU/fneg-combines.new.ll
index c4ca79dc85312..3de6df211ac7c 100644
--- a/llvm/test/CodeGen/AMDGPU/fneg-combines.new.ll
+++ b/llvm/test/CodeGen/AMDGPU/fneg-combines.new.ll
@@ -4441,25 +4441,40 @@ define float @v_fneg_fabs_select_infloop_regression(float %arg, i1 %arg1) {
   ret float %i3
 }
 
-define float @v_fmul_0_fsub_0_infloop_regression(float %arg) {
-; GCN-SAFE-LABEL: v_fmul_0_fsub_0_infloop_regression:
+define float @v_fmul_0_fsub_0_safe_infloop_regression(float %arg) {
+; GCN-SAFE-LABEL: v_fmul_0_fsub_0_safe_infloop_regression:
 ; GCN-SAFE:       ; %bb.0: ; %bb
 ; GCN-SAFE-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
 ; GCN-SAFE-NEXT:    v_mul_f32_e32 v0, 0, v0
 ; GCN-SAFE-NEXT:    v_sub_f32_e32 v0, 0, v0
 ; GCN-SAFE-NEXT:    s_setpc_b64 s[30:31]
 ;
-; GCN-NSZ-LABEL: v_fmul_0_fsub_0_infloop_regression:
-; GCN-NSZ:       ; %bb.0: ; %bb
-; GCN-NSZ-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GCN-NSZ-NEXT:    v_mul_f32_e32 v0, 0x80000000, v0
-; GCN-NSZ-NEXT:    s_setpc_b64 s[30:31]
+; SI-NSZ-LABEL: v_fmul_0_fsub_0_safe_infloop_regression:
+; SI-NSZ:       ; %bb.0: ; %bb
+; SI-NSZ-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; SI-NSZ-NEXT:    s_brev_b32 s4, 1
+; SI-NSZ-NEXT:    v_fma_f32 v0, v0, s4, 0
+; SI-NSZ-NEXT:    s_setpc_b64 s[30:31]
+; FIXME: utils/update_llc_test_checks.py will generate redundant VI
+; labels, remove them, they will cause test failure.
 bb:
   %i = fmul float %arg, 0.0
   %i1 = fsub float 0.0, %i
   ret float %i1
 }
 
+define float @v_fmul_0_fsub_0_nsz_infloop_regression(float %arg) {
+; GCN-LABEL: v_fmul_0_fsub_0_nsz_infloop_regression:
+; GCN:       ; %bb.0: ; %bb
+; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GCN-NEXT:    v_mul_f32_e32 v0, 0x80000000, v0
+; GCN-NEXT:    s_setpc_b64 s[30:31]
+bb:
+  %i = fmul float %arg, 0.0
+  %i1 = fsub nsz float 0.0, %i
+  ret float %i1
+}
+
 declare i32 @llvm.amdgcn.workitem.id.x() #1
 declare float @llvm.fma.f32(float, float, float) #1
 declare <2 x float> @llvm.fma.v2f32(<2 x float>, <2 x float>, <2 x float>)
diff --git a/llvm/test/CodeGen/X86/negative-sin.ll b/llvm/test/CodeGen/X86/negative-sin.ll
index f24507d3a4f38..4836da2ad7797 100644
--- a/llvm/test/CodeGen/X86/negative-sin.ll
+++ b/llvm/test/CodeGen/X86/negative-sin.ll
@@ -82,18 +82,13 @@ define double @semi_strict2(double %e) nounwind {
   ret double %h
 }
 
-; FIXME:
-; Auto-upgrade function attribute to IR-level fast-math-flags.
-
-define double @fn_attr(double %e) nounwind #0 {
-; CHECK-LABEL: fn_attr:
+define double @nsz_flag(double %e) nounwind {
+; CHECK-LABEL: nsz_flag:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    jmp sin@PLT # TAILCALL
-  %f = fsub double 0.0, %e
-  %g = call double @sin(double %f) readonly
-  %h = fsub double 0.0, %g
+  %f = fsub nsz double 0.0, %e
+  %g = call nsz double @sin(double %f) readonly
+  %h = fsub nsz double 0.0, %g
   ret double %h
 }
 
-attributes #0 = { "unsafe-fp-math"="true" "no-signed-zeros-fp-math"="true" }
-
diff --git a/llvm/test/CodeGen/X86/vec_unsafe-fp-math.ll b/llvm/test/CodeGen/X86/vec_unsafe-fp-math.ll
index 23d22e75d1e9d..3f92d2b79c85d 100644
--- a/llvm/test/CodeGen/X86/vec_unsafe-fp-math.ll
+++ b/llvm/test/CodeGen/X86/vec_unsafe-fp-math.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc < %s -enable-unsafe-fp-math -enable-no-signed-zeros-fp-math -mtriple=x86_64-unknown-unknown | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
 
 ; Make sure that vectors get the same benefits as scalars when using unsafe-fp-math.
 
@@ -18,7 +18,7 @@ define <4 x float> @vec_fneg(<4 x float> %x) {
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    xorps {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
 ; CHECK-NEXT:    retq
-  %sub = fsub <4 x float> zeroinitializer, %x
+  %sub = fsub nsz <4 x float> zeroinitializer, %x
   ret <4 x float> %sub
 }