AMDGPU/GlobalISel: Remove redundant G_FCANONICALIZE

[Petar.Avramovic]

Summary

G_FMINNUM_IEEE and G_FMAXNUM_IEEE are known to be never SNaN
and there is no need to quiet them using G_FCANONICALIZE.
Add post legalizer combine that deletes such G_FCANONICALIZE and
replaces its uses with input (G_FMINNUM_IEEE or G_FMAXNUM_IEEE) register.

[foad]

llvm/lib/Target/AMDGPU/AMDGPUPostLegalizerCombiner.cpp

257

You can use standard replaceSingleDefInstWithOperand or replaceSingleDefInstWithReg instead of defining your own apply function.

[Petar.Avramovic]

Use replaceSingleDefInstWithReg.

[arsenm]

llvm/lib/Target/AMDGPU/AMDGPUPostLegalizerCombiner.cpp

253–255

Really we should have an isCanonicalized utility function like we do in the DAG rather than special casing these two

[foad]

llvm/lib/Target/AMDGPU/AMDGPUPostLegalizerCombiner.cpp

250

I think the C should be capital too, matchRemoveFCanonicalize. This matches buildFCanonicalize in MIRBuilder.

[arsenm]

Should have isCanonicalize utility function

[Petar.Avramovic]

Added basic version of isCanonicalized for global-isel. Copied from sdag.

[arsenm]

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

9652

I don't think this really belongs in SITargetLowering, but I don't have a better suggestion for now

9658–9661

Duplicated / dead path for fcanonicalize. This meant G_FCONSTANT

9674

We shouldn't actually treat these generic instructions differently based on the subtarget, but I guess that's an existing problem

llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fcanonicalize.mir

170

Needs tests for the G_FCONSTANT cases

[foad]

Looks good to me apart from the G_FCONSTANT issues.

[Petar.Avramovic]

Fixed G_FCONSTANT and added test for it.

[foad]

LGTM.

llvm/lib/Target/AMDGPU/AMDGPUCombine.td

def int_minmax_to_med3 : GICombineRule<
   (defs root:$min_or_max, med3_matchdata:$matchinfo),
   (match (wip_match_opcode G_SMAX,
                            G_SMIN,
                            G_UMAX,
                            G_UMIN):$min_or_max,
          [{ return RegBankHelper.matchIntMinMaxToMed3(*${min_or_max}, ${matchinfo}); }]),
   (apply [{ RegBankHelper.applyMed3(*${min_or_max}, ${matchinfo}); }])>;
 
+def remove_fcanonicalize_matchinfo : GIDefMatchData<"Register">;
+
+def remove_fcanonicalize : GICombineRule<
+  (defs root:$fcanonicalize, remove_fcanonicalize_matchinfo:$matchinfo),
+  (match (wip_match_opcode G_FCANONICALIZE):$fcanonicalize,
+         [{ return PostLegalizerHelper.matchRemoveFcanonicalize(*${fcanonicalize}, ${matchinfo}); }]),
+  (apply [{ Helper.replaceSingleDefInstWithReg(*${fcanonicalize}, ${matchinfo}); }])>;
+
 // Combines which should only apply on SI/VI
 def gfx6gfx7_combines : GICombineGroup<[fcmp_select_to_fmin_fmax_legacy]>;
 
 def AMDGPUPreLegalizerCombinerHelper: GICombinerHelper<
   "AMDGPUGenPreLegalizerCombinerHelper", [all_combines, clamp_i64_to_i16]> {
   let DisableRuleOption = "amdgpuprelegalizercombiner-disable-rule";
   let StateClass = "AMDGPUPreLegalizerCombinerHelperState";
 }
 
 def AMDGPUPostLegalizerCombinerHelper: GICombinerHelper<
   "AMDGPUGenPostLegalizerCombinerHelper",
   [all_combines, gfx6gfx7_combines,
-   uchar_to_float, cvt_f32_ubyteN]> {
+   uchar_to_float, cvt_f32_ubyteN, remove_fcanonicalize]> {
   let DisableRuleOption = "amdgpupostlegalizercombiner-disable-rule";
   let StateClass = "AMDGPUPostLegalizerCombinerHelperState";
   let AdditionalArguments = [];
 }
 
 def AMDGPURegBankCombinerHelper : GICombinerHelper<
   "AMDGPUGenRegBankCombinerHelper", [zext_trunc_fold, int_minmax_to_med3]> {
   let DisableRuleOption = "amdgpuregbankcombiner-disable-rule";
   let StateClass = "AMDGPURegBankCombinerHelperState";
   let AdditionalArguments = [];
 }

llvm/lib/Target/AMDGPU/AMDGPUPostLegalizerCombiner.cpp

public:
   struct CvtF32UByteMatchInfo {
     Register CvtVal;
     unsigned ShiftOffset;
   };
 
   bool matchCvtF32UByteN(MachineInstr &MI, CvtF32UByteMatchInfo &MatchInfo);
   void applyCvtF32UByteN(MachineInstr &MI,
                          const CvtF32UByteMatchInfo &MatchInfo);
+
+  bool matchRemoveFcanonicalize(MachineInstr &MI, Register &Reg);
 };
 
 bool AMDGPUPostLegalizerCombinerHelper::matchFMinFMaxLegacy(
     MachineInstr &MI, FMinFMaxLegacyInfo &Info) {
   // FIXME: Combines should have subtarget predicates, and we shouldn't need
   // this here.
   if (!MF.getSubtarget<GCNSubtarget>().hasFminFmaxLegacy())
     return false;
if (SrcTy != S32) {
     CvtSrc = B.buildAnyExt(S32, CvtSrc).getReg(0);
   }
 
   assert(MI.getOpcode() != NewOpc);
   B.buildInstr(NewOpc, {MI.getOperand(0)}, {CvtSrc}, MI.getFlags());
   MI.eraseFromParent();
 }
 
+bool AMDGPUPostLegalizerCombinerHelper::matchRemoveFcanonicalize(
+    MachineInstr &MI, Register &Reg) {
+  const SITargetLowering *TLI = static_cast<const SITargetLowering *>(
+      MF.getSubtarget().getTargetLowering());
+  Reg = MI.getOperand(1).getReg();
+  return TLI->isCanonicalized(Reg, MF);
+}
+
 class AMDGPUPostLegalizerCombinerHelperState {
 protected:
   CombinerHelper &Helper;
   AMDGPUPostLegalizerCombinerHelper &PostLegalizerHelper;
 
 public:
   AMDGPUPostLegalizerCombinerHelperState(
       CombinerHelper &Helper,

llvm/lib/Target/AMDGPU/SIISelLowering.h

public:
   Align computeKnownAlignForTargetInstr(GISelKnownBits &Analysis, Register R,
                                         const MachineRegisterInfo &MRI,
                                         unsigned Depth = 0) const override;
   bool isSDNodeSourceOfDivergence(const SDNode *N,
     FunctionLoweringInfo *FLI, LegacyDivergenceAnalysis *DA) const override;
 
   bool isCanonicalized(SelectionDAG &DAG, SDValue Op,
                        unsigned MaxDepth = 5) const;
+  bool isCanonicalized(Register Reg, MachineFunction &MF,
+                       unsigned MaxDepth = 5) const;
   bool denormalsEnabledForType(const SelectionDAG &DAG, EVT VT) const;
+  bool denormalsEnabledForType(LLT Ty, MachineFunction &MF) const;
 
   bool isKnownNeverNaNForTargetNode(SDValue Op,
                                     const SelectionDAG &DAG,
                                     bool SNaN = false,
                                     unsigned Depth = 0) const override;
   AtomicExpansionKind shouldExpandAtomicRMWInIR(AtomicRMWInst *) const override;
 
   virtual const TargetRegisterClass *

llvm/lib/Target/AMDGPU/SIISelLowering.cpp

bool SITargetLowering::isCanonicalized(SelectionDAG &DAG, SDValue Op,
   default:
     return denormalsEnabledForType(DAG, Op.getValueType()) &&
            DAG.isKnownNeverSNaN(Op);
   }
 
   llvm_unreachable("invalid operation");
 }
 
+bool SITargetLowering::isCanonicalized(Register Reg, MachineFunction &MF,
+                                       unsigned MaxDepth) const {
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  MachineInstr *MI = MRI.getVRegDef(Reg);
+  unsigned Opcode = MI->getOpcode();
+
+  if (Opcode == AMDGPU::G_FCANONICALIZE)
+    return true;
+
+  if (Opcode == AMDGPU::G_FCONSTANT) {
+    auto F = MI->getOperand(1).getFPImm()->getValueAPF();
+    if (F.isNaN() && F.isSignaling())
+      return false;
+    return !F.isDenormal() || denormalsEnabledForType(MRI.getType(Reg), MF);
+  }
+
+  if (MaxDepth == 0)
+    return false;
+
+  switch (Opcode) {
+  case AMDGPU::G_FMINNUM_IEEE:
+  case AMDGPU::G_FMAXNUM_IEEE: {
+    if (Subtarget->supportsMinMaxDenormModes() ||
+        denormalsEnabledForType(MRI.getType(Reg), MF))
+      return true;
+    for (unsigned I = 1, E = MI->getNumOperands(); I != E; ++I) {
+      if (!isCanonicalized(MI->getOperand(I).getReg(), MF, MaxDepth - 1))
+        return false;
+    }
+    return true;
+  }
+  default:
+    return denormalsEnabledForType(MRI.getType(Reg), MF) &&
+           isKnownNeverSNaN(Reg, MRI);
+  }
+
+  llvm_unreachable("invalid operation");
+}
+
 // Constant fold canonicalize.
 SDValue SITargetLowering::getCanonicalConstantFP(
   SelectionDAG &DAG, const SDLoc &SL, EVT VT, const APFloat &C) const {
   // Flush denormals to 0 if not enabled.
   if (C.isDenormal() && !denormalsEnabledForType(DAG, VT))
     return DAG.getConstantFP(0.0, SL, VT);
 
   if (C.isNaN()) {
bool SITargetLowering::denormalsEnabledForType(const SelectionDAG &DAG,
   case MVT::f64:
   case MVT::f16:
     return hasFP64FP16Denormals(DAG.getMachineFunction());
   default:
     return false;
   }
 }
 
+bool SITargetLowering::denormalsEnabledForType(LLT Ty,
+                                               MachineFunction &MF) const {
+  switch (Ty.getScalarSizeInBits()) {
+  case 32:
+    return hasFP32Denormals(MF);
+  case 64:
+  case 16:
+    return hasFP64FP16Denormals(MF);
+  default:
+    return false;
+  }
+}
+
 bool SITargetLowering::isKnownNeverNaNForTargetNode(SDValue Op,
                                                     const SelectionDAG &DAG,
                                                     bool SNaN,
                                                     unsigned Depth) const {
   if (Op.getOpcode() == AMDGPUISD::CLAMP) {
     const MachineFunction &MF = DAG.getMachineFunction();
     const SIMachineFunctionInfo *Info = MF.getInfo<SIMachineFunctionInfo>();
 

llvm/test/CodeGen/AMDGPU/GlobalISel/combine-fcanonicalize.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -run-pass=amdgpu-postlegalizer-combiner -verify-machineinstrs %s -o - | FileCheck %s
+
+---
+name: test_fcanonicalize
+tracksRegLiveness: true
+legalized: true
+body: |
+  bb.0:
+    liveins: $vgpr0
+
+    ; CHECK-LABEL: name: test_fcanonicalize
+    ; CHECK: liveins: $vgpr0
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: $vgpr0 = COPY [[FCANONICALIZE]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = G_FCANONICALIZE %0
+    %2:_(s32) = G_FCANONICALIZE %1
+    $vgpr0 = COPY %2(s32)
+...
+
+---
+name: test_fconstant
+tracksRegLiveness: true
+legalized: true
+body: |
+  bb.0:
+
+    ; CHECK-LABEL: name: test_fconstant
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_FCONSTANT float 1.000000e+10
+    ; CHECK: $vgpr0 = COPY [[C]](s32)
+    %0:_(s32) = G_FCONSTANT float 1.0e10
+    %1:_(s32) = G_FCANONICALIZE %0
+    $vgpr0 = COPY %1(s32)
+...
+
+---
+name: test_denormal_fconstant
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    fp64-fp16-output-denormals: false
+    fp64-fp16-input-denormals: false
+body: |
+  bb.0:
+
+    ; CHECK-LABEL: name: test_denormal_fconstant
+    ; CHECK: [[C:%[0-9]+]]:_(s64) = G_FCONSTANT double 1.618950e-319
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s64) = G_FCANONICALIZE [[C]]
+    ; CHECK: $vgpr0_vgpr1 = COPY [[FCANONICALIZE]](s64)
+    %0:_(s64) = G_FCONSTANT double 0x0000000000008000
+    %1:_(s64) = G_FCANONICALIZE %0
+    $vgpr0_vgpr1 = COPY %1(s64)
+...
+
+---
+name: test_fminnum_with_fminnum_argument_s32_ieee_mode_on
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    ieee: true
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2
+
+    ; CHECK-LABEL: name: test_fminnum_with_fminnum_argument_s32_ieee_mode_on
+    ; CHECK: liveins: $vgpr0, $vgpr1, $vgpr2
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: [[FCANONICALIZE1:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY1]]
+    ; CHECK: [[FMINNUM_IEEE:%[0-9]+]]:_(s32) = G_FMINNUM_IEEE [[FCANONICALIZE]], [[FCANONICALIZE1]]
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[FCANONICALIZE2:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY2]]
+    ; CHECK: [[FMINNUM_IEEE1:%[0-9]+]]:_(s32) = G_FMINNUM_IEEE [[FMINNUM_IEEE]], [[FCANONICALIZE2]]
+    ; CHECK: $vgpr0 = COPY [[FMINNUM_IEEE1]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %7:_(s32) = G_FCANONICALIZE %0
+    %8:_(s32) = G_FCANONICALIZE %1
+    %2:_(s32) = G_FMINNUM_IEEE %7, %8
+    %3:_(s32) = COPY $vgpr2
+    %5:_(s32) = G_FCANONICALIZE %2
+    %6:_(s32) = G_FCANONICALIZE %3
+    %4:_(s32) = G_FMINNUM_IEEE %5, %6
+    $vgpr0 = COPY %4(s32)
+...
+
+---
+name: test_fminnum_with_fmaxnum_argument_s32_ieee_mode_on
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    ieee: true
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2
+
+    ; CHECK-LABEL: name: test_fminnum_with_fmaxnum_argument_s32_ieee_mode_on
+    ; CHECK: liveins: $vgpr0, $vgpr1, $vgpr2
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: [[FCANONICALIZE1:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY1]]
+    ; CHECK: [[FMAXNUM_IEEE:%[0-9]+]]:_(s32) = G_FMAXNUM_IEEE [[FCANONICALIZE]], [[FCANONICALIZE1]]
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[FCANONICALIZE2:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY2]]
+    ; CHECK: [[FMINNUM_IEEE:%[0-9]+]]:_(s32) = G_FMINNUM_IEEE [[FMAXNUM_IEEE]], [[FCANONICALIZE2]]
+    ; CHECK: $vgpr0 = COPY [[FMINNUM_IEEE]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %7:_(s32) = G_FCANONICALIZE %0
+    %8:_(s32) = G_FCANONICALIZE %1
+    %2:_(s32) = G_FMAXNUM_IEEE %7, %8
+    %3:_(s32) = COPY $vgpr2
+    %5:_(s32) = G_FCANONICALIZE %2
+    %6:_(s32) = G_FCANONICALIZE %3
+    %4:_(s32) = G_FMINNUM_IEEE %5, %6
+    $vgpr0 = COPY %4(s32)
+...
+
+---
+name: test_fmaxnum_with_fmaxnum_argument_s32_ieee_mode_on
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    ieee: true
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2
+
+    ; CHECK-LABEL: name: test_fmaxnum_with_fmaxnum_argument_s32_ieee_mode_on
+    ; CHECK: liveins: $vgpr0, $vgpr1, $vgpr2
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: [[FCANONICALIZE1:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY1]]
+    ; CHECK: [[FMAXNUM_IEEE:%[0-9]+]]:_(s32) = G_FMAXNUM_IEEE [[FCANONICALIZE]], [[FCANONICALIZE1]]
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[FCANONICALIZE2:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY2]]
+    ; CHECK: [[FMAXNUM_IEEE1:%[0-9]+]]:_(s32) = G_FMAXNUM_IEEE [[FMAXNUM_IEEE]], [[FCANONICALIZE2]]
+    ; CHECK: $vgpr0 = COPY [[FMAXNUM_IEEE1]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %7:_(s32) = G_FCANONICALIZE %0
+    %8:_(s32) = G_FCANONICALIZE %1
+    %2:_(s32) = G_FMAXNUM_IEEE %7, %8
+    %3:_(s32) = COPY $vgpr2
+    %5:_(s32) = G_FCANONICALIZE %2
+    %6:_(s32) = G_FCANONICALIZE %3
+    %4:_(s32) = G_FMAXNUM_IEEE %5, %6
+    $vgpr0 = COPY %4(s32)
+...
+
+---
+name: test_fmaxnum_with_fminnum_argument_s32_ieee_mode_on
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    ieee: true
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1, $vgpr2
+
+    ; CHECK-LABEL: name: test_fmaxnum_with_fminnum_argument_s32_ieee_mode_on
+    ; CHECK: liveins: $vgpr0, $vgpr1, $vgpr2
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: [[FCANONICALIZE1:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY1]]
+    ; CHECK: [[FMINNUM_IEEE:%[0-9]+]]:_(s32) = G_FMINNUM_IEEE [[FCANONICALIZE]], [[FCANONICALIZE1]]
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY $vgpr2
+    ; CHECK: [[FCANONICALIZE2:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY2]]
+    ; CHECK: [[FMAXNUM_IEEE:%[0-9]+]]:_(s32) = G_FMAXNUM_IEEE [[FMINNUM_IEEE]], [[FCANONICALIZE2]]
+    ; CHECK: $vgpr0 = COPY [[FMAXNUM_IEEE]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %7:_(s32) = G_FCANONICALIZE %0
+    %8:_(s32) = G_FCANONICALIZE %1
+    %2:_(s32) = G_FMINNUM_IEEE %7, %8
+    %3:_(s32) = COPY $vgpr2
+    %5:_(s32) = G_FCANONICALIZE %2
+    %6:_(s32) = G_FCANONICALIZE %3
+    %4:_(s32) = G_FMAXNUM_IEEE %5, %6
+    $vgpr0 = COPY %4(s32)
+...
+
+---
+name: test_multiple_uses
+tracksRegLiveness: true
+legalized: true
+machineFunctionInfo:
+  mode:
+    ieee: true
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: test_multiple_uses
+    ; CHECK: liveins: $vgpr0, $vgpr1
+    ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY $vgpr1
+    ; CHECK: [[FCANONICALIZE:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY]]
+    ; CHECK: [[FCANONICALIZE1:%[0-9]+]]:_(s32) = G_FCANONICALIZE [[COPY1]]
+    ; CHECK: [[FMINNUM_IEEE:%[0-9]+]]:_(s32) = G_FMINNUM_IEEE [[FCANONICALIZE]], [[FCANONICALIZE1]]
+    ; CHECK: [[FMAXNUM_IEEE:%[0-9]+]]:_(s32) = G_FMAXNUM_IEEE [[FMINNUM_IEEE]], [[FMINNUM_IEEE]]
+    ; CHECK: $vgpr0 = COPY [[FMAXNUM_IEEE]](s32)
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %6:_(s32) = G_FCANONICALIZE %0
+    %7:_(s32) = G_FCANONICALIZE %1
+    %2:_(s32) = G_FMINNUM_IEEE %6, %7
+    %4:_(s32) = G_FCANONICALIZE %2
+    %5:_(s32) = G_FCANONICALIZE %2
+    %3:_(s32) = G_FMAXNUM_IEEE %4, %5
+    $vgpr0 = COPY %3(s32)
+...

llvm/test/CodeGen/AMDGPU/GlobalISel/fmed3.ll

 ; SI-NEXT:    buffer_load_dword v4, v[0:1], s[8:11], 0 addr64 glc
 ; SI-NEXT:    s_waitcnt vmcnt(0)
 ; SI-NEXT:    v_sub_f32_e32 v2, 0x80000000, v2
 ; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v3
 ; SI-NEXT:    v_min_f32_e32 v5, v2, v3
 ; SI-NEXT:    v_max_f32_e32 v2, v2, v3
 ; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v4
-; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; SI-NEXT:    v_min_f32_e32 v2, v2, v3
-; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v5
-; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
-; SI-NEXT:    v_max_f32_e32 v2, v3, v2
+; SI-NEXT:    v_max_f32_e32 v2, v5, v2
 ; SI-NEXT:    s_mov_b64 s[2:3], s[10:11]
 ; SI-NEXT:    buffer_store_dword v2, v[0:1], s[0:3], 0 addr64
 ; SI-NEXT:    s_endpgm
 ;
 ; VI-LABEL: v_test_no_global_nnans_med3_f32_pat0_srcmod0:
 ; VI:       ; %bb.0:
 ; VI-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; VI-NEXT:    v_lshlrev_b32_e32 v6, 2, v0

 ; VI-NEXT:    v_add_u32_e32 v0, vcc, v0, v6
 ; VI-NEXT:    v_addc_u32_e32 v1, vcc, 0, v1, vcc
 ; VI-NEXT:    v_sub_f32_e32 v4, 0x80000000, v7
 ; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; VI-NEXT:    v_mul_f32_e32 v4, 1.0, v4
 ; VI-NEXT:    v_min_f32_e32 v5, v4, v2
 ; VI-NEXT:    v_max_f32_e32 v2, v4, v2
 ; VI-NEXT:    v_mul_f32_e32 v3, 1.0, v3
-; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; VI-NEXT:    v_min_f32_e32 v2, v2, v3
-; VI-NEXT:    v_mul_f32_e32 v3, 1.0, v5
-; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
-; VI-NEXT:    v_max_f32_e32 v2, v3, v2
+; VI-NEXT:    v_max_f32_e32 v2, v5, v2
 ; VI-NEXT:    flat_store_dword v[0:1], v2
 ; VI-NEXT:    s_endpgm
 ;
 ; GFX9-LABEL: v_test_no_global_nnans_med3_f32_pat0_srcmod0:
 ; GFX9:       ; %bb.0:
 ; GFX9-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; GFX9-NEXT:    v_lshlrev_b32_e32 v0, 2, v0
 ; GFX9-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX9-NEXT:    global_load_dword v1, v0, s[2:3] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    global_load_dword v2, v0, s[4:5] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    global_load_dword v3, v0, s[6:7] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    v_sub_f32_e32 v1, 0x80000000, v1
 ; GFX9-NEXT:    v_max_f32_e32 v2, v2, v2
 ; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX9-NEXT:    v_min_f32_e32 v4, v1, v2
 ; GFX9-NEXT:    v_max_f32_e32 v1, v1, v2
-; GFX9-NEXT:    v_max_f32_e32 v3, v3, v3
-; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
-; GFX9-NEXT:    v_min_f32_e32 v1, v1, v3
-; GFX9-NEXT:    v_max_f32_e32 v2, v4, v4
-; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
-; GFX9-NEXT:    v_max_f32_e32 v1, v2, v1
+; GFX9-NEXT:    v_max_f32_e32 v2, v3, v3
+; GFX9-NEXT:    v_min_f32_e32 v1, v1, v2
+; GFX9-NEXT:    v_max_f32_e32 v1, v4, v1
 ; GFX9-NEXT:    global_store_dword v0, v1, s[0:1]
 ; GFX9-NEXT:    s_endpgm
 ;
 ; GFX10-LABEL: v_test_no_global_nnans_med3_f32_pat0_srcmod0:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; GFX10-NEXT:    v_lshlrev_b32_e32 v0, 2, v0
 ; GFX10-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX10-NEXT:    global_load_dword v1, v0, s[2:3] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    global_load_dword v2, v0, s[4:5] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    global_load_dword v3, v0, s[6:7] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    v_sub_f32_e32 v1, 0x80000000, v1
 ; GFX10-NEXT:    v_max_f32_e32 v2, v2, v2
 ; GFX10-NEXT:    v_max_f32_e32 v3, v3, v3
 ; GFX10-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX10-NEXT:    v_max_f32_e32 v4, v1, v2
 ; GFX10-NEXT:    v_min_f32_e32 v1, v1, v2
-; GFX10-NEXT:    v_max_f32_e32 v4, v4, v4
-; GFX10-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX10-NEXT:    v_min_f32_e32 v2, v4, v3
-; GFX10-NEXT:    v_max_f32_e32 v2, v2, v2
 ; GFX10-NEXT:    v_max_f32_e32 v1, v1, v2
 ; GFX10-NEXT:    global_store_dword v0, v1, s[0:1]
 ; GFX10-NEXT:    s_endpgm
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
   %gep1 = getelementptr float, float addrspace(1)* %bptr, i32 %tid
   %gep2 = getelementptr float, float addrspace(1)* %cptr, i32 %tid
   %outgep = getelementptr float, float addrspace(1)* %out, i32 %tid

 ; SI-NEXT:    s_waitcnt vmcnt(0)
 ; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v3
 ; SI-NEXT:    v_min_f32_e32 v5, v2, v3
 ; SI-NEXT:    v_max_f32_e32 v2, v2, v3
 ; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v4
 ; SI-NEXT:    buffer_store_dword v5, off, s[0:3], 0
 ; SI-NEXT:    s_waitcnt vmcnt(0)
-; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; SI-NEXT:    v_min_f32_e32 v2, v2, v3
-; SI-NEXT:    v_mul_f32_e32 v3, 1.0, v5
-; SI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
-; SI-NEXT:    v_max_f32_e32 v2, v3, v2
+; SI-NEXT:    v_max_f32_e32 v2, v5, v2
 ; SI-NEXT:    s_mov_b64 s[2:3], s[10:11]
 ; SI-NEXT:    buffer_store_dword v2, v[0:1], s[0:3], 0 addr64
 ; SI-NEXT:    s_endpgm
 ;
 ; VI-LABEL: v_test_safe_med3_f32_pat0_multi_use0:
 ; VI:       ; %bb.0:
 ; VI-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; VI-NEXT:    v_lshlrev_b32_e32 v6, 2, v0

 ; VI-NEXT:    s_waitcnt vmcnt(0)
 ; VI-NEXT:    v_mov_b32_e32 v0, s0
 ; VI-NEXT:    v_mov_b32_e32 v1, s1
 ; VI-NEXT:    v_add_u32_e32 v0, vcc, v0, v6
 ; VI-NEXT:    v_addc_u32_e32 v1, vcc, 0, v1, vcc
 ; VI-NEXT:    v_mul_f32_e32 v4, 1.0, v7
 ; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
 ; VI-NEXT:    v_min_f32_e32 v5, v4, v2
-; VI-NEXT:    v_max_f32_e32 v2, v4, v2
 ; VI-NEXT:    v_mul_f32_e32 v3, 1.0, v3
-; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
+; VI-NEXT:    v_max_f32_e32 v2, v4, v2
 ; VI-NEXT:    v_min_f32_e32 v2, v2, v3
-; VI-NEXT:    v_mul_f32_e32 v3, 1.0, v5
-; VI-NEXT:    v_mul_f32_e32 v2, 1.0, v2
-; VI-NEXT:    v_max_f32_e32 v2, v3, v2
+; VI-NEXT:    v_max_f32_e32 v2, v5, v2
 ; VI-NEXT:    flat_store_dword v[0:1], v5
 ; VI-NEXT:    s_waitcnt vmcnt(0)
 ; VI-NEXT:    flat_store_dword v[0:1], v2
 ; VI-NEXT:    s_endpgm
 ;
 ; GFX9-LABEL: v_test_safe_med3_f32_pat0_multi_use0:
 ; GFX9:       ; %bb.0:
 ; GFX9-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; GFX9-NEXT:    v_lshlrev_b32_e32 v0, 2, v0
 ; GFX9-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX9-NEXT:    global_load_dword v1, v0, s[2:3] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    global_load_dword v2, v0, s[4:5] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    global_load_dword v3, v0, s[6:7] glc
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX9-NEXT:    v_max_f32_e32 v2, v2, v2
 ; GFX9-NEXT:    v_min_f32_e32 v4, v1, v2
 ; GFX9-NEXT:    v_max_f32_e32 v1, v1, v2
+; GFX9-NEXT:    v_max_f32_e32 v3, v3, v3
 ; GFX9-NEXT:    global_store_dword v[0:1], v4, off
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
-; GFX9-NEXT:    v_max_f32_e32 v3, v3, v3
-; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX9-NEXT:    v_min_f32_e32 v1, v1, v3
-; GFX9-NEXT:    v_max_f32_e32 v2, v4, v4
-; GFX9-NEXT:    v_max_f32_e32 v1, v1, v1
-; GFX9-NEXT:    v_max_f32_e32 v1, v2, v1
+; GFX9-NEXT:    v_max_f32_e32 v1, v4, v1
 ; GFX9-NEXT:    global_store_dword v0, v1, s[0:1]
 ; GFX9-NEXT:    s_endpgm
 ;
 ; GFX10-LABEL: v_test_safe_med3_f32_pat0_multi_use0:
 ; GFX10:       ; %bb.0:
 ; GFX10-NEXT:    s_load_dwordx8 s[0:7], s[0:1], 0x24
 ; GFX10-NEXT:    v_lshlrev_b32_e32 v0, 2, v0
 ; GFX10-NEXT:    s_waitcnt lgkmcnt(0)
 ; GFX10-NEXT:    global_load_dword v1, v0, s[2:3] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    global_load_dword v2, v0, s[4:5] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    global_load_dword v3, v0, s[6:7] glc dlc
 ; GFX10-NEXT:    s_waitcnt vmcnt(0)
 ; GFX10-NEXT:    v_max_f32_e32 v1, v1, v1
 ; GFX10-NEXT:    v_max_f32_e32 v2, v2, v2
 ; GFX10-NEXT:    v_max_f32_e32 v3, v3, v3
 ; GFX10-NEXT:    v_max_f32_e32 v4, v1, v2
 ; GFX10-NEXT:    v_min_f32_e32 v1, v1, v2
-; GFX10-NEXT:    v_max_f32_e32 v4, v4, v4
 ; GFX10-NEXT:    v_min_f32_e32 v2, v4, v3
-; GFX10-NEXT:    v_max_f32_e32 v3, v1, v1
-; GFX10-NEXT:    v_max_f32_e32 v2, v2, v2
-; GFX10-NEXT:    v_max_f32_e32 v2, v3, v2
+; GFX10-NEXT:    v_max_f32_e32 v2, v1, v2
 ; GFX10-NEXT:    global_store_dword v[0:1], v1, off
 ; GFX10-NEXT:    s_waitcnt_vscnt null, 0x0
 ; GFX10-NEXT:    global_store_dword v0, v2, s[0:1]
 ; GFX10-NEXT:    s_endpgm
   %tid = call i32 @llvm.amdgcn.workitem.id.x()
   %gep0 = getelementptr float, float addrspace(1)* %aptr, i32 %tid
   %gep1 = getelementptr float, float addrspace(1)* %bptr, i32 %tid
   %gep2 = getelementptr float, float addrspace(1)* %cptr, i32 %tid