[llvm] [AMDGPU] Use std::optional in InstCombine of amdgcn_fmed3. NFC. (PR #108223)

[Jay Foad via llvm-commits]

https://github.com/jayfoad updated https://github.com/llvm/llvm-project/pull/108223

>From a344ef5cd8b2cfb08618efdade36be3f65ad59c7 Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad at amd.com>
Date: Wed, 11 Sep 2024 14:27:05 +0100
Subject: [PATCH 1/2] [AMDGPU] Use std::optional in InstCombine of
 amdgcn_fmed3. NFC.

---
 .../AMDGPU/AMDGPUInstCombineIntrinsic.cpp     | 36 +++++++++----------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index 4da3618357c420..a2135fbc254c11 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -353,23 +353,20 @@ bool GCNTTIImpl::canSimplifyLegacyMulToMul(const Instruction &I,
 }
 
 /// Match an fpext from half to float, or a constant we can convert.
-static bool matchFPExtFromF16(Value *Arg, Value *&FPExtSrc) {
-  if (match(Arg, m_OneUse(m_FPExt(m_Value(FPExtSrc)))))
-    return FPExtSrc->getType()->isHalfTy();
-
+static std::optional<Value *> matchFPExtFromF16(Value *Arg) {
+  Value *Src;
   ConstantFP *CFP;
-  if (match(Arg, m_ConstantFP(CFP))) {
+  if (match(Arg, m_OneUse(m_FPExt(m_Value(Src))))) {
+    if (Src->getType()->isHalfTy())
+      return Src;
+  } else if (match(Arg, m_ConstantFP(CFP))) {
     bool LosesInfo;
     APFloat Val(CFP->getValueAPF());
     Val.convert(APFloat::IEEEhalf(), APFloat::rmNearestTiesToEven, &LosesInfo);
-    if (LosesInfo)
-      return false;
-
-    FPExtSrc = ConstantFP::get(Type::getHalfTy(Arg->getContext()), Val);
-    return true;
+    if (!LosesInfo)
+      return ConstantFP::get(Type::getHalfTy(Arg->getContext()), Val);
   }
-
-  return false;
+  return {};
 }
 
 // Trim all zero components from the end of the vector \p UseV and return
@@ -839,15 +836,16 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
     if (!ST->hasMed3_16())
       break;
 
-    Value *X, *Y, *Z;
-
     // Repeat floating-point width reduction done for minnum/maxnum.
     // fmed3((fpext X), (fpext Y), (fpext Z)) -> fpext (fmed3(X, Y, Z))
-    if (matchFPExtFromF16(Src0, X) && matchFPExtFromF16(Src1, Y) &&
-        matchFPExtFromF16(Src2, Z)) {
-      Value *NewCall = IC.Builder.CreateIntrinsic(IID, {X->getType()},
-                                                  {X, Y, Z}, &II, II.getName());
-      return new FPExtInst(NewCall, II.getType());
+    if (auto X = matchFPExtFromF16(Src0)) {
+      if (auto Y = matchFPExtFromF16(Src1)) {
+        if (auto Z = matchFPExtFromF16(Src2)) {
+          Value *NewCall = IC.Builder.CreateIntrinsic(
+              IID, {(*X)->getType()}, {*X, *Y, *Z}, &II, II.getName());
+          return new FPExtInst(NewCall, II.getType());
+        }
+      }
     }
 
     break;

>From eebbb4c2b093d7166e3c8727932a9265b142217c Mon Sep 17 00:00:00 2001
From: Jay Foad <jay.foad at amd.com>
Date: Wed, 11 Sep 2024 14:49:03 +0100
Subject: [PATCH 2/2] address review comments

---
 llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
index a2135fbc254c11..d6b953932a940b 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
@@ -354,8 +354,8 @@ bool GCNTTIImpl::canSimplifyLegacyMulToMul(const Instruction &I,
 
 /// Match an fpext from half to float, or a constant we can convert.
 static std::optional<Value *> matchFPExtFromF16(Value *Arg) {
-  Value *Src;
-  ConstantFP *CFP;
+  Value *Src = nullptr;
+  ConstantFP *CFP = nullptr;
   if (match(Arg, m_OneUse(m_FPExt(m_Value(Src))))) {
     if (Src->getType()->isHalfTy())
       return Src;
@@ -366,7 +366,7 @@ static std::optional<Value *> matchFPExtFromF16(Value *Arg) {
     if (!LosesInfo)
       return ConstantFP::get(Type::getHalfTy(Arg->getContext()), Val);
   }
-  return {};
+  return std::nullopt;
 }
 
 // Trim all zero components from the end of the vector \p UseV and return