[FPEnv][AMDGPU] Disable FSUB(-0,X)->FNEG(X) DAGCombine when subnormals are flushed

[cameron.mcinally]

Summary

One more push on this before the year is over...

This patch disables the FSUB(-0,X)->FNEG(X) DAG combine when we're flushing subnormals. It requires updating the existing AMDGPU tests to use the fneg IR instruction, in place of the old fsub(-0,X) canonical form, since AMDGPU is the only backend currently checking the DenormalMode flags.

Note that this will require follow-up optimizations to make sure the fsub(-0,X) form is handled appropriately. But I think that can be done in a separate patch.

[arsenm]

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

13375

This will also change the behavior on signaling nans, which will no longer quiet

[cameron.mcinally]

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

13375

Good catch.

I'm playing with a change to only allow this transform when NoNaNs are present, but it's breaking a lot of tests across a number of targets. How would you feel about leaving that change to a separate patch? I think this subnormal Diff is a step in the right direction, and doesn't regress from the current behavior.

[arsenm]

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

13375

Should get a fixme at least (we also have an isKnownNeverSNan although it's fairly limited)

[cameron.mcinally]

Add FIXME comment.

[cameron.mcinally]

Ping.

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

SDValue DAGCombiner::visitFSUB(SDNode *N) {
 
   if (N0 == N1) {
     // (fsub x, x) -> 0.0
     if (Options.NoNaNsFPMath || Flags.hasNoNaNs())
       return DAG.getConstantFP(0.0f, DL, VT);
   }
 
   // (fsub -0.0, N1) -> -N1
-  // NOTE: It is safe to transform an FSUB(-0.0,X) into an FNEG(X), since the
-  //       FSUB does not specify the sign bit of a NaN. Also note that for
-  //       the same reason, the inverse transform is not safe, unless fast math
-  //       flags are in play.
   if (N0CFP && N0CFP->isZero()) {
     if (N0CFP->isNegative() ||
         (Options.NoSignedZerosFPMath || 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
+      // of a signaling NaN. It is only valid when a NoNaN flag is present.
+      DenormalMode DenormMode = DAG.getDenormalMode(VT);
+      if (DenormMode == DenormalMode::getIEEE()) {
         if (SDValue NegN1 =
                 TLI.getNegatedExpression(N1, DAG, LegalOperations, ForCodeSize))
           return NegN1;
         if (!LegalOperations || TLI.isOperationLegal(ISD::FNEG, VT))
           return DAG.getNode(ISD::FNEG, DL, VT, N1);
       }
     }
+  }
 
   if (((Options.UnsafeFPMath && Options.NoSignedZerosFPMath) ||
        (Flags.hasAllowReassociation() && Flags.hasNoSignedZeros())) &&
       N1.getOpcode() == ISD::FADD) {
     // X - (X + Y) -> -Y
     if (N0 == N1->getOperand(0))
       return DAG.getNode(ISD::FNEG, DL, VT, N1->getOperand(1));
     // X - (Y + X) -> -Y

llvm/test/CodeGen/AMDGPU/clamp-modifier.ll

 ; GCN: v_floor_f32_e32 [[FLOOR:v[0-9]+]], [[A]]
 ; GCN: v_max_f32_e64 v{{[0-9]+}}, -[[FLOOR]], -[[FLOOR]] clamp{{$}}
 define amdgpu_kernel void @v_clamp_add_neg_src_f32(float addrspace(1)* %out, float addrspace(1)* %aptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
   %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
   %a = load float, float addrspace(1)* %gep0
   %floor = call float @llvm.floor.f32(float %a)
-  %neg.floor = fsub float -0.0, %floor
+  %neg.floor = fneg float %floor
   %max = call float @llvm.maxnum.f32(float %neg.floor, float 0.0)
   %clamp = call float @llvm.minnum.f32(float %max, float 1.0)
   store float %clamp, float addrspace(1)* %out.gep
   ret void
 }
 
 ; GCN-LABEL: {{^}}v_non_clamp_max_f32:
 ; GCN: {{buffer|flat|global}}_load_dword [[A:v[0-9]+]]

llvm/test/CodeGen/AMDGPU/clamp.ll

 ; GCN-LABEL: {{^}}v_clamp_neg_f32:
 ; GCN: {{buffer|flat|global}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_max_f32_e64 v{{[0-9]+}}, -[[A]], -[[A]] clamp{{$}}
 define amdgpu_kernel void @v_clamp_neg_f32(float addrspace(1)* %out, float addrspace(1)* %aptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
   %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
   %a = load float, float addrspace(1)* %gep0
-  %fneg.a = fsub float -0.0, %a
+  %fneg.a = fneg float %a
   %max = call float @llvm.maxnum.f32(float %fneg.a, float 0.0)
   %med = call float @llvm.minnum.f32(float %max, float 1.0)
 
   store float %med, float addrspace(1)* %out.gep
   ret void
 }
 
 ; GCN-LABEL: {{^}}v_clamp_negabs_f32:
 ; GCN: {{buffer|flat|global}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_max_f32_e64 v{{[0-9]+}}, -|[[A]]|, -|[[A]]| clamp{{$}}
 define amdgpu_kernel void @v_clamp_negabs_f32(float addrspace(1)* %out, float addrspace(1)* %aptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
   %out.gep = getelementptr float, float addrspace(1)* %out, i32 %tid
   %a = load float, float addrspace(1)* %gep0
   %fabs.a = call float @llvm.fabs.f32(float %a)
-  %fneg.fabs.a = fsub float -0.0, %fabs.a
+  %fneg.fabs.a = fneg float %fabs.a
 
   %max = call float @llvm.maxnum.f32(float %fneg.fabs.a, float 0.0)
   %med = call float @llvm.minnum.f32(float %max, float 1.0)
 
   store float %med, float addrspace(1)* %out.gep
   ret void
 }
 

llvm/test/CodeGen/AMDGPU/fdiv32-to-rcp-folding.ll

 ; GCN-DENORM:     v_rcp_f32_e32 [[RCP:v[0-9]+]], [[PRESCALED]]
 ; GCN-DENORM:     v_mul_f32_e32 [[OUT:v[0-9]+]], [[SCALE]], [[RCP]]
 
 ; GCN-FLUSH:      v_rcp_f32_e64 [[OUT:v[0-9]+]], -[[VAL]]
 
 ; GCN:            global_store_dword v{{[0-9]+}}, [[OUT]], s{{\[[0-9]+:[0-9]+\]}}
 define amdgpu_kernel void @div_1_by_minus_x_25ulp(float addrspace(1)* %arg) {
   %load = load float, float addrspace(1)* %arg, align 4
-  %neg = fsub float -0.000000e+00, %load
+  %neg = fneg float %load
   %div = fdiv float 1.000000e+00, %neg, !fpmath !0
   store float %div, float addrspace(1)* %arg, align 4
   ret void
 }
 
 ; GCN-LABEL: {{^}}div_minus_1_by_minus_x_25ulp:
 ; GCN-DENORM-DAG: v_mov_b32_e32 [[L:v[0-9]+]], 0x6f800000
 ; GCN-DENORM-DAG: v_mov_b32_e32 [[S:v[0-9]+]], 0x2f800000

 
 ; GCN-FLUSH:      v_rcp_f32_e64 v[[OUT0:[0-9]+]], -s[[VAL0]]
 ; GCN-FLUSH:      v_rcp_f32_e64
 ; GCN-FLUSH:      v_rcp_f32_e64
 ; GCN-FLUSH:      v_rcp_f32_e64 v[[OUT3:[0-9]+]], -s[[VAL3]]
 ; GCN-FLUSH:      global_store_dwordx4 v{{[0-9]+}}, v{{\[}}[[OUT0]]:[[OUT3]]], s{{\[[0-9]+:[0-9]+\]}}
 define amdgpu_kernel void @div_v4_1_by_minus_x_25ulp(<4 x float> addrspace(1)* %arg) {
   %load = load <4 x float>, <4 x float> addrspace(1)* %arg, align 16
-  %neg = fsub <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, %load
+  %neg = fneg <4 x float> %load
   %div = fdiv <4 x float> <float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00>, %neg, !fpmath !0
   store <4 x float> %div, <4 x float> addrspace(1)* %arg, align 16
   ret void
 }
 
 ; GCN-LABEL: {{^}}div_v4_minus_1_by_minus_x_25ulp:
 ; GCN-DAG:        s_load_dwordx4 s{{\[}}[[VAL0:[0-9]+]]:[[VAL3:[0-9]+]]], s[{{[0-9:]+}}], 0x0{{$}}
 ; GCN-DENORM-DAG: v_mov_b32_e32 [[L:v[0-9]+]], 0x6f800000

 
 ; GCN-FLUSH:      v_rcp_f32_e32 v[[OUT0:[0-9]+]], s[[VAL0]]
 ; GCN-FLUSH:      v_rcp_f32_e32
 ; GCN-FLUSH:      v_rcp_f32_e32
 ; GCN-FLUSH:      v_rcp_f32_e32 v[[OUT3:[0-9]+]], s[[VAL3]]
 ; GCN-FLUSH:      global_store_dwordx4 v{{[0-9]+}}, v{{\[}}[[OUT0]]:[[OUT3]]], s{{\[[0-9]+:[0-9]+\]}}
 define amdgpu_kernel void @div_v4_minus_1_by_minus_x_25ulp(<4 x float> addrspace(1)* %arg) {
   %load = load <4 x float>, <4 x float> addrspace(1)* %arg, align 16
-  %neg = fsub <4 x float> <float -0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>, %load
+  %neg = fneg <4 x float> %load
   %div = fdiv <4 x float> <float -1.000000e+00, float -1.000000e+00, float -1.000000e+00, float -1.000000e+00>, %neg, !fpmath !0
   store <4 x float> %div, <4 x float> addrspace(1)* %arg, align 16
   ret void
 }
 
 ; GCN-LABEL: {{^}}div_v4_c_by_x_25ulp:
 ; GCN-DENORM-DAG: v_div_scale_f32 {{.*}}, 2.0{{$}}
 ; GCN-DENORM-DAG: v_div_scale_f32 {{.*}}, 2.0{{$}}

 }
 
 ; GCN-LABEL: {{^}}div_1_by_minus_x_fast:
 ; GCN: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0x0
 ; GCN: v_rcp_f32_e64 [[RCP:v[0-9]+]], -[[VAL]]
 ; GCN: global_store_dword v{{[0-9]+}}, [[RCP]], s{{\[[0-9]+:[0-9]+\]}}
 define amdgpu_kernel void @div_1_by_minus_x_fast(float addrspace(1)* %arg) {
   %load = load float, float addrspace(1)* %arg, align 4
-  %neg = fsub float -0.000000e+00, %load, !fpmath !0
+  %neg = fneg float %load, !fpmath !0
   %div = fdiv fast float 1.000000e+00, %neg
   store float %div, float addrspace(1)* %arg, align 4
   ret void
 }
 
 ; GCN-LABEL: {{^}}div_minus_1_by_minus_x_fast:
 ; GCN: s_load_dword [[VAL:s[0-9]+]], s[0:1], 0x0
 ; GCN: v_rcp_f32_e32 [[RCP:v[0-9]+]], [[VAL]]

llvm/test/CodeGen/AMDGPU/fma-combine.ll

define amdgpu_kernel void @fma_neg_2.0_neg_a_b_f32(float addrspace(1)* %out, float addrspace(1)* %in) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep.0 = getelementptr float, float addrspace(1)* %out, i32 %tid
   %gep.1 = getelementptr float, float addrspace(1)* %gep.0, i32 1
   %gep.out = getelementptr float, float addrspace(1)* %out, i32 %tid
 
   %r1 = load volatile float, float addrspace(1)* %gep.0
   %r2 = load volatile float, float addrspace(1)* %gep.1
 
-  %r1.fneg = fsub float -0.000000e+00, %r1
+  %r1.fneg = fneg float %r1
 
   %r3 = tail call float @llvm.fma.f32(float -2.0, float %r1.fneg, float %r2)
   store float %r3, float addrspace(1)* %gep.out
   ret void
 }
 
 ; SI-LABEL: {{^}}fma_2.0_neg_a_b_f32:
 ; SI: {{buffer|flat|global}}_load_dword [[A:v[0-9]+]]
 ; SI: {{buffer|flat|global}}_load_dword [[B:v[0-9]+]]
 ; SI-NOT: [[A]]
 ; SI-NOT: [[B]]
 ; SI: v_fma_f32 v{{[0-9]+}}, [[A]], -2.0, [[B]]
 define amdgpu_kernel void @fma_2.0_neg_a_b_f32(float addrspace(1)* %out, float addrspace(1)* %in) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep.0 = getelementptr float, float addrspace(1)* %out, i32 %tid
   %gep.1 = getelementptr float, float addrspace(1)* %gep.0, i32 1
   %gep.out = getelementptr float, float addrspace(1)* %out, i32 %tid
 
   %r1 = load volatile float, float addrspace(1)* %gep.0
   %r2 = load volatile float, float addrspace(1)* %gep.1
 
-  %r1.fneg = fsub float -0.000000e+00, %r1
+  %r1.fneg = fneg float %r1
 
   %r3 = tail call float @llvm.fma.f32(float 2.0, float %r1.fneg, float %r2)
   store float %r3, float addrspace(1)* %gep.out
   ret void
 }
 
 ; SI-LABEL: {{^}}fma_neg_b_c_v4f32:
 ; SI: v_fma_f32 v{{[0-9]+}}, v{{[0-9]+}}, -v{{[0-9]+}}, -v{{[0-9]+}}

llvm/test/CodeGen/AMDGPU/fneg-combines.ll

 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_self_minnum_f32_ieee(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %min = call float @llvm.minnum.f32(float %a, float %a)
-  %min.fneg = fsub float -0.0, %min
+  %min.fneg = fneg float %min
   store float %min.fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; GCN-LABEL: {{^}}v_fneg_self_minnum_f32_no_ieee:
 ; GCN-NOT: v0
 ; GCN: v_max_f32_e64 v0, -v0, -v0
 ; GCN-NEXT: ; return
 define amdgpu_ps float @v_fneg_self_minnum_f32_no_ieee(float %a) #0 {
   %min = call float @llvm.minnum.f32(float %a, float %a)
-  %min.fneg = fsub float -0.0, %min
+  %min.fneg = fneg float %min
   ret float %min.fneg
 }
 
 ; GCN-LABEL: {{^}}v_fneg_posk_minnum_f32_ieee:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_mul_f32_e32 [[QUIET_NEG_A:v[0-9]+]], -1.0, [[A]]
 ; GCN: v_max_f32_e32 [[RESULT:v[0-9]+]], -4.0, [[QUIET_NEG_A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]

 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_self_maxnum_f32_ieee(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %max = call float @llvm.maxnum.f32(float %a, float %a)
-  %max.fneg = fsub float -0.0, %max
+  %max.fneg = fneg float %max
   store float %max.fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; GCN-LABEL: {{^}}v_fneg_self_maxnum_f32_no_ieee:
 ; GCN-NOT: v0
 ; GCN: v_min_f32_e64 v0, -v0, -v0
 ; GCN-NEXT: ; return
 define amdgpu_ps float @v_fneg_self_maxnum_f32_no_ieee(float %a) #0 {
   %max = call float @llvm.maxnum.f32(float %a, float %a)
-  %max.fneg = fsub float -0.0, %max
+  %max.fneg = fneg float %max
   ret float %max.fneg
 }
 
 ; GCN-LABEL: {{^}}v_fneg_posk_maxnum_f32_ieee:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_mul_f32_e32 [[QUIET_NEG_A:v[0-9]+]], -1.0, [[A]]
 ; GCN: v_min_f32_e32 [[RESULT:v[0-9]+]], -4.0, [[QUIET_NEG_A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]

 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_amdgcn_sin_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %sin = call float @llvm.amdgcn.sin.f32(float %a)
-  %fneg = fsub float -0.0, %sin
+  %fneg = fneg float %sin
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; ftrunc tests
 ; --------------------------------------------------------------------------------
 
 ; GCN-LABEL: {{^}}v_fneg_trunc_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_trunc_f32_e64 [[RESULT:v[0-9]+]], -[[A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_trunc_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %trunc = call float @llvm.trunc.f32(float %a)
-  %fneg = fsub float -0.0, %trunc
+  %fneg = fneg float %trunc
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; fround tests
 ; --------------------------------------------------------------------------------
 

 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_round_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %round = call float @llvm.round.f32(float %a)
-  %fneg = fsub float -0.0, %round
+  %fneg = fneg float %round
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; rint tests
 ; --------------------------------------------------------------------------------
 
 ; GCN-LABEL: {{^}}v_fneg_rint_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_rndne_f32_e64 [[RESULT:v[0-9]+]], -[[A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_rint_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %rint = call float @llvm.rint.f32(float %a)
-  %fneg = fsub float -0.0, %rint
+  %fneg = fneg float %rint
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; nearbyint tests
 ; --------------------------------------------------------------------------------
 
 ; GCN-LABEL: {{^}}v_fneg_nearbyint_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_rndne_f32_e64 [[RESULT:v[0-9]+]], -[[A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_nearbyint_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %nearbyint = call float @llvm.nearbyint.f32(float %a)
-  %fneg = fsub float -0.0, %nearbyint
+  %fneg = fneg float %nearbyint
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; fcanonicalize tests
 ; --------------------------------------------------------------------------------
 
 ; GCN-LABEL: {{^}}v_fneg_canonicalize_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: v_mul_f32_e32 [[RESULT:v[0-9]+]], -1.0, [[A]]
 ; GCN: flat_store_dword v{{\[[0-9]+:[0-9]+\]}}, [[RESULT]]
 define amdgpu_kernel void @v_fneg_canonicalize_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %trunc = call float @llvm.canonicalize.f32(float %a)
-  %fneg = fsub float -0.0, %trunc
+  %fneg = fneg float %trunc
   store float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; vintrp tests
 ; --------------------------------------------------------------------------------
 
 ; GCN-LABEL: {{^}}v_fneg_interp_p1_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: {{buffer|flat}}_load_dword [[B:v[0-9]+]]
 ; GCN: v_mul_f32_e64 [[MUL:v[0-9]+]], [[A]], -[[B]]
 ; GCN: v_interp_p1_f32{{(_e32)?}} v{{[0-9]+}}, [[MUL]]
 ; GCN: v_interp_p1_f32{{(_e32)?}} v{{[0-9]+}}, [[MUL]]
 define amdgpu_kernel void @v_fneg_interp_p1_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %mul = fmul float %a, %b
-  %fneg = fsub float -0.0, %mul
+  %fneg = fneg float %mul
   %intrp0 = call float @llvm.amdgcn.interp.p1(float %fneg, i32 0, i32 0, i32 0)
   %intrp1 = call float @llvm.amdgcn.interp.p1(float %fneg, i32 1, i32 0, i32 0)
   store volatile float %intrp0, float addrspace(1)* %out.gep
   store volatile float %intrp1, float addrspace(1)* %out.gep
   ret void
 }
 
 ; GCN-LABEL: {{^}}v_fneg_interp_p2_f32:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: {{buffer|flat}}_load_dword [[B:v[0-9]+]]
 ; GCN: v_mul_f32_e64 [[MUL:v[0-9]+]], [[A]], -[[B]]
 ; GCN: v_interp_p2_f32{{(_e32)?}} v{{[0-9]+}}, [[MUL]]
 ; GCN: v_interp_p2_f32{{(_e32)?}} v{{[0-9]+}}, [[MUL]]
 define amdgpu_kernel void @v_fneg_interp_p2_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr) #0 {
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %tid.ext = sext i32 %tid to i64
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %mul = fmul float %a, %b
-  %fneg = fsub float -0.0, %mul
+  %fneg = fneg float %mul
   %intrp0 = call float @llvm.amdgcn.interp.p2(float 4.0, float %fneg, i32 0, i32 0, i32 0)
   %intrp1 = call float @llvm.amdgcn.interp.p2(float 4.0, float %fneg, i32 1, i32 0, i32 0)
   store volatile float %intrp0, float addrspace(1)* %out.gep
   store volatile float %intrp1, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
define amdgpu_kernel void @v_fneg_copytoreg_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, i32 %d) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %mul = fmul float %a, %b
-  %fneg = fsub float -0.0, %mul
+  %fneg = fneg float %mul
   %cmp0 = icmp eq i32 %d, 0
   br i1 %cmp0, label %if, label %endif
 
 if:
   %mul1 = fmul float %fneg, %c
   store volatile float %mul1, float addrspace(1)* %out.gep
   br label %endif
 
define amdgpu_kernel void @v_fneg_inlineasm_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, i32 %d) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %mul = fmul float %a, %b
-  %fneg = fsub float -0.0, %mul
+  %fneg = fneg float %mul
   call void asm sideeffect "; use $0", "v"(float %fneg) #0
   store volatile float %fneg, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; inlineasm tests
 ; --------------------------------------------------------------------------------
define amdgpu_kernel void @v_fneg_inlineasm_multi_use_src_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, i32 %d) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %mul = fmul float %a, %b
-  %fneg = fsub float -0.0, %mul
+  %fneg = fneg float %mul
   call void asm sideeffect "; use $0", "v"(float %fneg) #0
   store volatile float %mul, float addrspace(1)* %out.gep
   ret void
 }
 
 ; --------------------------------------------------------------------------------
 ; code size regression tests
 ; --------------------------------------------------------------------------------
define amdgpu_kernel void @multiuse_fneg_2_vop3_users_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
 
-  %fneg.a = fsub float -0.0, %a
+  %fneg.a = fneg float %a
   %fma0 = call float @llvm.fma.f32(float %fneg.a, float %b, float %c)
   %fma1 = call float @llvm.fma.f32(float %fneg.a, float %c, float 2.0)
 
   store volatile float %fma0, float addrspace(1)* %out
   store volatile float %fma1, float addrspace(1)* %out
   ret void
 }
 
define amdgpu_kernel void @multiuse_fneg_2_vop2_users_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
 
-  %fneg.a = fsub float -0.0, %a
+  %fneg.a = fneg float %a
   %mul0 = fmul float %fneg.a, %b
   %mul1 = fmul float %fneg.a, %c
 
   store volatile float %mul0, float addrspace(1)* %out
   store volatile float %mul1, float addrspace(1)* %out
   ret void
 }
 
define amdgpu_kernel void @multiuse_fneg_vop2_vop3_users_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr) #0 {
   %a.gep = getelementptr inbounds float, float addrspace(1)* %a.ptr, i64 %tid.ext
   %b.gep = getelementptr inbounds float, float addrspace(1)* %b.ptr, i64 %tid.ext
   %c.gep = getelementptr inbounds float, float addrspace(1)* %c.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
 
-  %fneg.a = fsub float -0.0, %a
+  %fneg.a = fneg float %a
   %fma0 = call float @llvm.fma.f32(float %fneg.a, float %b, float 2.0)
   %mul1 = fmul float %fneg.a, %c
 
   store volatile float %fma0, float addrspace(1)* %out
   store volatile float %mul1, float addrspace(1)* %out
   ret void
 }
 
define amdgpu_kernel void @free_fold_src_code_size_cost_use_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, float addrspace(1)* %d.ptr) #0 {
   %d.gep = getelementptr inbounds float, float addrspace(1)* %d.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %d = load volatile float, float addrspace(1)* %d.gep
 
   %fma0 = call float @llvm.fma.f32(float %a, float %b, float 2.0)
-  %fneg.fma0 = fsub float -0.0, %fma0
+  %fneg.fma0 = fneg float %fma0
   %mul1 = fmul float %fneg.fma0, %c
   %mul2 = fmul float %fneg.fma0, %d
 
   store volatile float %mul1, float addrspace(1)* %out
   store volatile float %mul2, float addrspace(1)* %out
   ret void
 }
 
define amdgpu_kernel void @one_use_cost_to_fold_into_src_f32(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, float addrspace(1)* %d.ptr) #0 {
   %d.gep = getelementptr inbounds float, float addrspace(1)* %d.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %d = load volatile float, float addrspace(1)* %d.gep
 
   %trunc.a = call float @llvm.trunc.f32(float %a)
-  %trunc.fneg.a = fsub float -0.0, %trunc.a
+  %trunc.fneg.a = fneg float %trunc.a
   %fma0 = call float @llvm.fma.f32(float %trunc.fneg.a, float %b, float %c)
   store volatile float %fma0, float addrspace(1)* %out
   ret void
 }
 
 ; GCN-LABEL: {{^}}multi_use_cost_to_fold_into_src:
 ; GCN: {{buffer|flat}}_load_dword [[A:v[0-9]+]]
 ; GCN: {{buffer|flat}}_load_dword [[B:v[0-9]+]]
define amdgpu_kernel void @multi_use_cost_to_fold_into_src(float addrspace(1)* %out, float addrspace(1)* %a.ptr, float addrspace(1)* %b.ptr, float addrspace(1)* %c.ptr, float addrspace(1)* %d.ptr) #0 {
   %d.gep = getelementptr inbounds float, float addrspace(1)* %d.ptr, i64 %tid.ext
   %out.gep = getelementptr inbounds float, float addrspace(1)* %out, i64 %tid.ext
   %a = load volatile float, float addrspace(1)* %a.gep
   %b = load volatile float, float addrspace(1)* %b.gep
   %c = load volatile float, float addrspace(1)* %c.gep
   %d = load volatile float, float addrspace(1)* %d.gep
 
   %trunc.a = call float @llvm.trunc.f32(float %a)
-  %trunc.fneg.a = fsub float -0.0, %trunc.a
+  %trunc.fneg.a = fneg float %trunc.a
   %fma0 = call float @llvm.fma.f32(float %trunc.fneg.a, float %b, float %c)
   %mul1 = fmul float %trunc.a, %d
   store volatile float %fma0, float addrspace(1)* %out
   store volatile float %mul1, float addrspace(1)* %out
   ret void
 }
 
 declare i32 @llvm.amdgcn.workitem.id.x() #1

llvm/test/CodeGen/AMDGPU/fpext-free.ll

 ; GFX9-F32DENORM-NEXT: v_mul_f16_e64 v0, v0, -v1
 ; GFX9-F32DENORM-NEXT: v_cvt_f32_f16_e32 v0, v0
 ; GFX9-F32DENORM-NEXT: v_sub_f32_e32 v0, v0, v2
 ; GFX9-F32DENORM-NEXT: s_setpc_b64
 define float @fsub_fneg_fpext_fmul_f16_to_f32(half %x, half %y, float %z) #0 {
 entry:
   %mul = fmul half %x, %y
   %mul.ext = fpext half %mul to float
-  %neg.mul.ext = fsub float -0.0, %mul.ext
+  %neg.mul.ext = fneg float %mul.ext
   %add = fsub float %neg.mul.ext, %z
   ret float %add
 }
 
 ; fold (fsub (fmad x, y, (fpext (fmul u, v))), z)
 ;    -> (fmad x, y (fmad (fpext u), (fpext v), (fneg z)))
 ; GCN-LABEL: {{^}}fsub_muladd_fpext_mul_f16_to_f32:
 ; GCN: s_waitcnt

llvm/test/CodeGen/AMDGPU/fptrunc.f16.ll

 ; GCN: v_cvt_f16_f32_e64 v[[R_F16:[0-9]+]], -v[[A_F32]]
 ; GCN: buffer_store_short v[[R_F16]]
 ; GCN: s_endpgm
 define amdgpu_kernel void @fneg_fptrunc_f32_to_f16(
     half addrspace(1)* %r,
     float addrspace(1)* %a) {
 entry:
   %a.val = load float, float addrspace(1)* %a
-  %a.fneg = fsub float -0.0, %a.val
+  %a.fneg = fneg float %a.val
   %r.val = fptrunc float %a.fneg to half
   store half %r.val, half addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}fabs_fptrunc_f32_to_f16:
 ; GCN: buffer_load_dword v[[A_F32:[0-9]+]]
 ; GCN: v_cvt_f16_f32_e64 v[[R_F16:[0-9]+]], |v[[A_F32]]|

 ; GCN: buffer_store_short v[[R_F16]]
 ; GCN: s_endpgm
 define amdgpu_kernel void @fneg_fabs_fptrunc_f32_to_f16(
     half addrspace(1)* %r,
     float addrspace(1)* %a) #0 {
 entry:
   %a.val = load float, float addrspace(1)* %a
   %a.fabs = call float @llvm.fabs.f32(float %a.val)
-  %a.fneg.fabs = fsub float -0.0, %a.fabs
+  %a.fneg.fabs = fneg float %a.fabs
   %r.val = fptrunc float %a.fneg.fabs to half
   store half %r.val, half addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}fptrunc_f32_to_f16_zext_i32:
 ; GCN: buffer_load_dword v[[A_F32:[0-9]+]]
 ; GCN: v_cvt_f16_f32_e32 v[[R_F16:[0-9]+]], v[[A_F32]]

llvm/test/CodeGen/AMDGPU/known-never-snan.ll

 define float @v_test_known_not_snan_fneg_input_fmed3_r_i_i_f32(float %a) #0 {
 ; GCN-LABEL: v_test_known_not_snan_fneg_input_fmed3_r_i_i_f32:
 ; GCN:       ; %bb.0:
 ; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
 ; GCN-NEXT:    v_rcp_f32_e32 v0, v0
 ; GCN-NEXT:    v_med3_f32 v0, -v0, 2.0, 4.0
 ; GCN-NEXT:    s_setpc_b64 s[30:31]
   %a.nnan.add = fdiv nnan float 1.0, %a, !fpmath !0
-  %known.not.snan = fsub float -0.0, %a.nnan.add
+  %known.not.snan = fneg float %a.nnan.add
   %max = call float @llvm.maxnum.f32(float %known.not.snan, float 2.0)
   %med = call float @llvm.minnum.f32(float %max, float 4.0)
   ret float %med
 }
 
 define float @v_test_known_not_snan_fpext_input_fmed3_r_i_i_f32(half %a) #0 {
 ; GCN-LABEL: v_test_known_not_snan_fpext_input_fmed3_r_i_i_f32:
 ; GCN:       ; %bb.0:

llvm/test/CodeGen/AMDGPU/llvm.amdgcn.fmad.ftz.ll

 define amdgpu_kernel void @mad_f32_neg_b(
     float addrspace(1)* %r,
     float addrspace(1)* %a,
     float addrspace(1)* %b,
     float addrspace(1)* %c) {
   %a.val = load float, float addrspace(1)* %a
   %b.val = load float, float addrspace(1)* %b
   %c.val = load float, float addrspace(1)* %c
-  %neg.b = fsub float -0.0, %b.val
+  %neg.b = fneg float %b.val
   %r.val = call float @llvm.amdgcn.fmad.ftz.f32(float %a.val, float %neg.b, float %c.val)
   store float %r.val, float addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mad_f32_abs_b:
 ; GCN:  v_mad_f32 v{{[0-9]+}}, s{{[0-9]+}}, |v{{[0-9]+}}|, v{{[0-9]+}}
 define amdgpu_kernel void @mad_f32_abs_b(
define amdgpu_kernel void @mad_f32_neg_abs_b(
     float addrspace(1)* %r,
     float addrspace(1)* %a,
     float addrspace(1)* %b,
     float addrspace(1)* %c) {
   %a.val = load float, float addrspace(1)* %a
   %b.val = load float, float addrspace(1)* %b
   %c.val = load float, float addrspace(1)* %c
   %abs.b = call float @llvm.fabs.f32(float %b.val)
-  %neg.abs.b = fsub float -0.0, %abs.b
+  %neg.abs.b = fneg float %abs.b
   %r.val = call float @llvm.amdgcn.fmad.ftz.f32(float %a.val, float %neg.abs.b, float %c.val)
   store float %r.val, float addrspace(1)* %r
   ret void
 }
 
 declare float @llvm.fabs.f32(float)

llvm/test/CodeGen/AMDGPU/mad-combine.ll

define amdgpu_kernel void @combine_to_mad_fsub_2_f32(float addrspace(1)* noalias %out, float addrspace(1)* noalias %in) #1 {
   %gep.2 = getelementptr float, float addrspace(1)* %gep.0, i32 2
   %gep.out = getelementptr float, float addrspace(1)* %out, i32 %tid
 
   %a = load volatile float, float addrspace(1)* %gep.0
   %b = load volatile float, float addrspace(1)* %gep.1
   %c = load volatile float, float addrspace(1)* %gep.2
 
   %mul = fmul float %a, %b
-  %mul.neg = fsub float -0.0, %mul
+  %mul.neg = fneg float %mul
   %fma = fsub float %mul.neg, %c
 
   store float %fma, float addrspace(1)* %gep.out
   ret void
 }
 
 ; (fsub (fneg (fmul x, y)), z) -> (fma (fneg x), y, (fneg z))
 ; FUNC-LABEL: {{^}}combine_to_mad_fsub_2_f32_2uses_neg:
define amdgpu_kernel void @combine_to_mad_fsub_2_f32_2uses_neg(float addrspace(1)* noalias %out, float addrspace(1)* noalias %in) #1 {
   %gep.out.1 = getelementptr float, float addrspace(1)* %gep.out.0, i32 1
 
   %a = load volatile float, float addrspace(1)* %gep.0
   %b = load volatile float, float addrspace(1)* %gep.1
   %c = load volatile float, float addrspace(1)* %gep.2
   %d = load volatile float, float addrspace(1)* %gep.3
 
   %mul = fmul float %a, %b
-  %mul.neg = fsub float -0.0, %mul
+  %mul.neg = fneg float %mul
   %fma0 = fsub float %mul.neg, %c
   %fma1 = fsub float %mul.neg, %d
 
   store volatile float %fma0, float addrspace(1)* %gep.out.0
   store volatile float %fma1, float addrspace(1)* %gep.out.1
   ret void
 }
 
define amdgpu_kernel void @combine_to_mad_fsub_2_f32_2uses_mul(float addrspace(1)* noalias %out, float addrspace(1)* noalias %in) #1 {
   %gep.out.1 = getelementptr float, float addrspace(1)* %gep.out.0, i32 1
 
   %a = load volatile float, float addrspace(1)* %gep.0
   %b = load volatile float, float addrspace(1)* %gep.1
   %c = load volatile float, float addrspace(1)* %gep.2
   %d = load volatile float, float addrspace(1)* %gep.3
 
   %mul = fmul float %a, %b
-  %mul.neg = fsub float -0.0, %mul
+  %mul.neg = fneg float %mul
   %fma0 = fsub float %mul.neg, %c
   %fma1 = fsub float %mul, %d
 
   store volatile float %fma0, float addrspace(1)* %gep.out.0
   store volatile float %fma1, float addrspace(1)* %gep.out.1
   ret void
 }
 

llvm/test/CodeGen/AMDGPU/mad-mix.ll

 ; GFX906-NEXT: v_fma_mix_f32 v0, -v0, v1, v2  op_sel_hi:[1,1,1] ; encoding
 ; GFX906-NEXT: s_setpc_b64
 
 ; CIVI: v_mad_f32
 define float @v_mad_mix_f32_negf16lo_f16lo_f16lo(half %src0, half %src1, half %src2) #0 {
   %src0.ext = fpext half %src0 to float
   %src1.ext = fpext half %src1 to float
   %src2.ext = fpext half %src2 to float
-  %src0.ext.neg = fsub float -0.0, %src0.ext
+  %src0.ext.neg = fneg float %src0.ext
   %result = tail call float @llvm.fmuladd.f32(float %src0.ext.neg, float %src1.ext, float %src2.ext)
   ret float %result
 }
 
 ; GCN-LABEL: {{^}}v_mad_mix_f32_absf16lo_f16lo_f16lo:
 ; GFX900: v_mad_mix_f32 v0, |v0|, v1, v2 op_sel_hi:[1,1,1]
 ; GFX906: v_fma_mix_f32 v0, |v0|, v1, v2 op_sel_hi:[1,1,1]
 

 ; GFX906-NEXT: s_setpc_b64
 
 ; CIVI: v_mad_f32
 define float @v_mad_mix_f32_negabsf16lo_f16lo_f16lo(half %src0, half %src1, half %src2) #0 {
   %src0.ext = fpext half %src0 to float
   %src1.ext = fpext half %src1 to float
   %src2.ext = fpext half %src2 to float
   %src0.ext.abs = call float @llvm.fabs.f32(float %src0.ext)
-  %src0.ext.neg.abs = fsub float -0.0, %src0.ext.abs
+  %src0.ext.neg.abs = fneg float %src0.ext.abs
   %result = tail call float @llvm.fmuladd.f32(float %src0.ext.neg.abs, float %src1.ext, float %src2.ext)
   ret float %result
 }
 
 ; GCN-LABEL: {{^}}v_mad_mix_f32_f16lo_f16lo_f32:
 ; GCN: s_waitcnt
 ; GFX900-NEXT: v_mad_mix_f32 v0, v0, v1, v2 op_sel_hi:[1,1,0] ; encoding
 ; GFX906-NEXT: v_fma_mix_f32 v0, v0, v1, v2 op_sel_hi:[1,1,0] ; encoding

 ; GFX900-NEXT: v_mad_mix_f32 v0, v0, v1, -v2 op_sel_hi:[1,1,0] ; encoding
 ; GFX906-NEXT: v_fma_mix_f32 v0, v0, v1, -v2 op_sel_hi:[1,1,0] ; encoding
 ; GFX9-NEXT: s_setpc_b64
 
 ; CIVI: v_mad_f32
 define float @v_mad_mix_f32_f16lo_f16lo_negf32(half %src0, half %src1, float %src2) #0 {
   %src0.ext = fpext half %src0 to float
   %src1.ext = fpext half %src1 to float
-  %src2.neg = fsub float -0.0, %src2
+  %src2.neg = fneg float %src2
   %result = tail call float @llvm.fmuladd.f32(float %src0.ext, float %src1.ext, float %src2.neg)
   ret float %result
 }
 
 ; GCN-LABEL: {{^}}v_mad_mix_f32_f16lo_f16lo_absf32:
 ; GCN: s_waitcnt
 ; GFX900-NEXT: v_mad_mix_f32 v0, v0, v1, |v2| op_sel_hi:[1,1,0] ; encoding
 ; GFX906-NEXT: v_fma_mix_f32 v0, v0, v1, |v2| op_sel_hi:[1,1,0] ; encoding

 ; GFX906-NEXT: v_fma_mix_f32 v0, v0, v1, -|v2| op_sel_hi:[1,1,0] ; encoding
 ; GFX9-NEXT: s_setpc_b64
 
 ; CIVI: v_mad_f32
 define float @v_mad_mix_f32_f16lo_f16lo_negabsf32(half %src0, half %src1, float %src2) #0 {
   %src0.ext = fpext half %src0 to float
   %src1.ext = fpext half %src1 to float
   %src2.abs = call float @llvm.fabs.f32(float %src2)
-  %src2.neg.abs = fsub float -0.0, %src2.abs
+  %src2.neg.abs = fneg float %src2.abs
   %result = tail call float @llvm.fmuladd.f32(float %src0.ext, float %src1.ext, float %src2.neg.abs)
   ret float %result
 }
 
 ; TODO: Fold inline immediates. Need to be careful because it is an
 ; f16 inline immediate that may be converted to f32, not an actual f32
 ; inline immediate.
 

llvm/test/CodeGen/AMDGPU/rcp-pattern.ll

 }
 
 ; FUNC-LABEL: {{^}}rcp_fabs_fneg_pat_f32:
 ; GCN: s_load_dword [[SRC:s[0-9]+]]
 ; GCN: v_rcp_f32_e64 [[RCP:v[0-9]+]], -|[[SRC]]|
 ; GCN: buffer_store_dword [[RCP]]
 define amdgpu_kernel void @rcp_fabs_fneg_pat_f32(float addrspace(1)* %out, float %src) #0 {
   %src.fabs = call float @llvm.fabs.f32(float %src)
-  %src.fabs.fneg = fsub float -0.0, %src.fabs
+  %src.fabs.fneg = fneg float %src.fabs
   %rcp = fdiv float 1.0, %src.fabs.fneg, !fpmath !0
   store float %rcp, float addrspace(1)* %out, align 4
   ret void
 }
 
 ; FUNC-LABEL: {{^}}rcp_fabs_fneg_pat_multi_use_f32:
 ; GCN: s_load_dword [[SRC:s[0-9]+]]
 ; GCN: v_rcp_f32_e64 [[RCP:v[0-9]+]], -|[[SRC]]|
 ; GCN: v_mul_f32_e64 [[MUL:v[0-9]+]], [[SRC]], -|[[SRC]]|
 ; GCN: buffer_store_dword [[RCP]]
 ; GCN: buffer_store_dword [[MUL]]
 define amdgpu_kernel void @rcp_fabs_fneg_pat_multi_use_f32(float addrspace(1)* %out, float %src) #0 {
   %src.fabs = call float @llvm.fabs.f32(float %src)
-  %src.fabs.fneg = fsub float -0.0, %src.fabs
+  %src.fabs.fneg = fneg float %src.fabs
   %rcp = fdiv float 1.0, %src.fabs.fneg, !fpmath !0
   store volatile float %rcp, float addrspace(1)* %out, align 4
 
   %other = fmul float %src, %src.fabs.fneg
   store volatile float %other, float addrspace(1)* %out, align 4
   ret void
 }
 

llvm/test/CodeGen/AMDGPU/rsq.ll

 ; SI-SAFE: v_rcp_f32_e64 [[RSQ:v[0-9]+]], -[[SQRT]]
 ; SI-SAFE: buffer_store_dword [[RSQ]]
 
 ; SI-UNSAFE: v_sqrt_f32_e64 [[SQRT:v[0-9]+]], -v{{[0-9]+}}
 ; SI-UNSAFE: v_rcp_f32_e64 [[RSQ:v[0-9]+]], -[[SQRT]]
 ; SI-UNSAFE: buffer_store_dword [[RSQ]]
 define amdgpu_kernel void @neg_rsq_neg_f32(float addrspace(1)* noalias %out, float addrspace(1)* noalias %in) #0 {
   %val = load float, float addrspace(1)* %in, align 4
-  %val.fneg = fsub float -0.0, %val
+  %val.fneg = fneg float %val
   %sqrt = call float @llvm.sqrt.f32(float %val.fneg)
   %div = fdiv float -1.0, %sqrt, !fpmath !0
   store float %div, float addrspace(1)* %out, align 4
   ret void
 }
 
 ; SI-LABEL: {{^}}neg_rsq_neg_f64:
 ; SI-SAFE: v_sqrt_f64_e64 v{{\[[0-9]+:[0-9]+\]}}, -v{{\[[0-9]+:[0-9]+\]}}

llvm/test/CodeGen/AMDGPU/v_mac.ll

 entry:
   %b_ptr = getelementptr float, float addrspace(1)* %in, i32 1
   %c_ptr = getelementptr float, float addrspace(1)* %in, i32 2
 
   %a = load float, float addrspace(1)* %in
   %b = load float, float addrspace(1)* %b_ptr
   %c = load float, float addrspace(1)* %c_ptr
 
-  %neg_a = fsub float -0.0, %a
+  %neg_a = fneg float %a
   %tmp0 = fmul float %neg_a, %b
   %tmp1 = fadd float %tmp0, %c
 
   store float %tmp1, float addrspace(1)* %out
   ret void
 }
 
 ; GCN-LABEL: {{^}}nsz_mad_sub0_src0:

 entry:
   %b_ptr = getelementptr float, float addrspace(1)* %in, i32 1
   %c_ptr = getelementptr float, float addrspace(1)* %in, i32 2
 
   %a = load float, float addrspace(1)* %in
   %b = load float, float addrspace(1)* %b_ptr
   %c = load float, float addrspace(1)* %c_ptr
 
-  %neg_b = fsub float -0.0, %b
+  %neg_b = fneg float %b
   %tmp0 = fmul float %a, %neg_b
   %tmp1 = fadd float %tmp0, %c
 
   store float %tmp1, float addrspace(1)* %out
   ret void
 }
 
 ; GCN-LABEL: {{^}}nsz_mad_sub0_src1:

 entry:
   %b_ptr = getelementptr float, float addrspace(1)* %in, i32 1
   %c_ptr = getelementptr float, float addrspace(1)* %in, i32 2
 
   %a = load float, float addrspace(1)* %in
   %b = load float, float addrspace(1)* %b_ptr
   %c = load float, float addrspace(1)* %c_ptr
 
-  %neg_c = fsub float -0.0, %c
+  %neg_c = fneg float %c
   %tmp0 = fmul float %a, %b
   %tmp1 = fadd float %tmp0, %neg_c
 
   store float %tmp1, float addrspace(1)* %out
   ret void
 }
 
 ; Without special casing the inline constant check for v_mac_f32's

llvm/test/CodeGen/AMDGPU/v_mac_f16.ll

define amdgpu_kernel void @mac_f16_neg_a(
     half addrspace(1)* %a,
     half addrspace(1)* %b,
     half addrspace(1)* %c) #0 {
 entry:
   %a.val = load half, half addrspace(1)* %a
   %b.val = load half, half addrspace(1)* %b
   %c.val = load half, half addrspace(1)* %c
 
-  %a.neg = fsub half -0.0, %a.val
+  %a.neg = fneg half %a.val
   %t.val = fmul half %a.neg, %b.val
   %r.val = fadd half %t.val, %c.val
 
   store half %r.val, half addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_f16_neg_b:
define amdgpu_kernel void @mac_f16_neg_b(
     half addrspace(1)* %a,
     half addrspace(1)* %b,
     half addrspace(1)* %c) #0 {
 entry:
   %a.val = load half, half addrspace(1)* %a
   %b.val = load half, half addrspace(1)* %b
   %c.val = load half, half addrspace(1)* %c
 
-  %b.neg = fsub half -0.0, %b.val
+  %b.neg = fneg half %b.val
   %t.val = fmul half %a.val, %b.neg
   %r.val = fadd half %t.val, %c.val
 
   store half %r.val, half addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_f16_neg_c:
define amdgpu_kernel void @mac_f16_neg_c(
     half addrspace(1)* %a,
     half addrspace(1)* %b,
     half addrspace(1)* %c) #0 {
 entry:
   %a.val = load half, half addrspace(1)* %a
   %b.val = load half, half addrspace(1)* %b
   %c.val = load half, half addrspace(1)* %c
 
-  %c.neg = fsub half -0.0, %c.val
+  %c.neg = fneg half %c.val
   %t.val = fmul half %a.val, %b.val
   %r.val = fadd half %t.val, %c.neg
 
   store half %r.val, half addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_f16_neg_a_safe_fp_math:
define amdgpu_kernel void @mac_v2f16_neg_a(
     <2 x half> addrspace(1)* %a,
     <2 x half> addrspace(1)* %b,
     <2 x half> addrspace(1)* %c) #0 {
 entry:
   %a.val = load <2 x half>, <2 x half> addrspace(1)* %a
   %b.val = load <2 x half>, <2 x half> addrspace(1)* %b
   %c.val = load <2 x half>, <2 x half> addrspace(1)* %c
 
-  %a.neg = fsub <2 x half> <half -0.0, half -0.0>, %a.val
+  %a.neg = fneg <2 x half> %a.val
   %t.val = fmul <2 x half> %a.neg, %b.val
   %r.val = fadd <2 x half> %t.val, %c.val
 
   store <2 x half> %r.val, <2 x half> addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_v2f16_neg_b
define amdgpu_kernel void @mac_v2f16_neg_b(
     <2 x half> addrspace(1)* %a,
     <2 x half> addrspace(1)* %b,
     <2 x half> addrspace(1)* %c) #0 {
 entry:
   %a.val = load <2 x half>, <2 x half> addrspace(1)* %a
   %b.val = load <2 x half>, <2 x half> addrspace(1)* %b
   %c.val = load <2 x half>, <2 x half> addrspace(1)* %c
 
-  %b.neg = fsub <2 x half> <half -0.0, half -0.0>, %b.val
+  %b.neg = fneg <2 x half> %b.val
   %t.val = fmul <2 x half> %a.val, %b.neg
   %r.val = fadd <2 x half> %t.val, %c.val
 
   store <2 x half> %r.val, <2 x half> addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_v2f16_neg_c:
define amdgpu_kernel void @mac_v2f16_neg_c(
     <2 x half> addrspace(1)* %a,
     <2 x half> addrspace(1)* %b,
     <2 x half> addrspace(1)* %c) #0 {
 entry:
   %a.val = load <2 x half>, <2 x half> addrspace(1)* %a
   %b.val = load <2 x half>, <2 x half> addrspace(1)* %b
   %c.val = load <2 x half>, <2 x half> addrspace(1)* %c
 
-  %c.neg = fsub <2 x half> <half -0.0, half -0.0>, %c.val
+  %c.neg = fneg <2 x half> %c.val
   %t.val = fmul <2 x half> %a.val, %b.val
   %r.val = fadd <2 x half> %t.val, %c.neg
 
   store <2 x half> %r.val, <2 x half> addrspace(1)* %r
   ret void
 }
 
 ; GCN-LABEL: {{^}}mac_v2f16_neg_a_safe_fp_math: