[llvm] 8325189 - [NFC][InstCombine] Refactor InstCombinerImpl::foldSelectIntoOp

[David Sherwood via llvm-commits]

Author: David Sherwood
Date: 2022-06-13T10:37:07+01:00
New Revision: 83251896d74bf0df85259b2e65b701aa14355705

URL: https://github.com/llvm/llvm-project/commit/83251896d74bf0df85259b2e65b701aa14355705
DIFF: https://github.com/llvm/llvm-project/commit/83251896d74bf0df85259b2e65b701aa14355705.diff

LOG: [NFC][InstCombine] Refactor InstCombinerImpl::foldSelectIntoOp

Introduce a lambda function so that we remove a lot of code
duplication.

Differential Revision: https://reviews.llvm.org/D127493

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index c18e8f856b2f..f49e74b28801 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -439,79 +439,56 @@ Instruction *InstCombinerImpl::foldSelectIntoOp(SelectInst &SI, Value *TrueVal,
                                                 Value *FalseVal) {
   // See the comment above GetSelectFoldableOperands for a description of the
   // transformation we are doing here.
-  if (auto *TVI = dyn_cast<BinaryOperator>(TrueVal)) {
-    if (TVI->hasOneUse() && !isa<Constant>(FalseVal)) {
-      if (unsigned SFO = getSelectFoldableOperands(TVI)) {
-        unsigned OpToFold = 0;
-        if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
-          OpToFold = 1;
-        } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
-          OpToFold = 2;
-        }
-
-        if (OpToFold) {
-          FastMathFlags FMF;
-          if (isa<FPMathOperator>(&SI))
-            FMF = SI.getFastMathFlags();
-          Constant *C = ConstantExpr::getBinOpIdentity(
-              TVI->getOpcode(), TVI->getType(), true, FMF.noSignedZeros());
-          Value *OOp = TVI->getOperand(2-OpToFold);
-          // Avoid creating select between 2 constants unless it's selecting
-          // between 0, 1 and -1.
-          const APInt *OOpC;
-          bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
-          if (!isa<Constant>(OOp) ||
-              (OOpIsAPInt && isSelect01(C->getUniqueInteger(), *OOpC))) {
-            Value *NewSel = Builder.CreateSelect(SI.getCondition(), OOp, C);
+  auto TryFoldSelectIntoOp = [&](SelectInst &SI, Value *TrueVal,
+                                 Value *FalseVal,
+                                 bool Swapped) -> Instruction * {
+    if (auto *TVI = dyn_cast<BinaryOperator>(TrueVal)) {
+      if (TVI->hasOneUse() && !isa<Constant>(FalseVal)) {
+        if (unsigned SFO = getSelectFoldableOperands(TVI)) {
+          unsigned OpToFold = 0;
+          if ((SFO & 1) && FalseVal == TVI->getOperand(0))
+            OpToFold = 1;
+          else if ((SFO & 2) && FalseVal == TVI->getOperand(1))
+            OpToFold = 2;
+
+          if (OpToFold) {
+            FastMathFlags FMF;
+            // TODO: We probably ought to revisit cases where the select and FP
+            // instructions have 
diff erent flags and add tests to ensure the
+            // behaviour is correct.
             if (isa<FPMathOperator>(&SI))
-              cast<Instruction>(NewSel)->setFastMathFlags(FMF);
-            NewSel->takeName(TVI);
-            BinaryOperator *BO = BinaryOperator::Create(TVI->getOpcode(),
-                                                        FalseVal, NewSel);
-            BO->copyIRFlags(TVI);
-            return BO;
+              FMF = SI.getFastMathFlags();
+            Constant *C = ConstantExpr::getBinOpIdentity(
+                TVI->getOpcode(), TVI->getType(), true, FMF.noSignedZeros());
+            Value *OOp = TVI->getOperand(2 - OpToFold);
+            // Avoid creating select between 2 constants unless it's selecting
+            // between 0, 1 and -1.
+            const APInt *OOpC;
+            bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
+            if (!isa<Constant>(OOp) ||
+                (OOpIsAPInt && isSelect01(C->getUniqueInteger(), *OOpC))) {
+              Value *NewSel = Builder.CreateSelect(
+                  SI.getCondition(), Swapped ? C : OOp, Swapped ? OOp : C);
+              if (isa<FPMathOperator>(&SI))
+                cast<Instruction>(NewSel)->setFastMathFlags(FMF);
+              NewSel->takeName(TVI);
+              BinaryOperator *BO =
+                  BinaryOperator::Create(TVI->getOpcode(), FalseVal, NewSel);
+              BO->copyIRFlags(TVI);
+              return BO;
+            }
           }
         }
       }
     }
-  }
+    return nullptr;
+  };
 
-  if (auto *FVI = dyn_cast<BinaryOperator>(FalseVal)) {
-    if (FVI->hasOneUse() && !isa<Constant>(TrueVal)) {
-      if (unsigned SFO = getSelectFoldableOperands(FVI)) {
-        unsigned OpToFold = 0;
-        if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
-          OpToFold = 1;
-        } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
-          OpToFold = 2;
-        }
+  if (Instruction *R = TryFoldSelectIntoOp(SI, TrueVal, FalseVal, false))
+    return R;
 
-        if (OpToFold) {
-          FastMathFlags FMF;
-          if (isa<FPMathOperator>(&SI))
-            FMF = SI.getFastMathFlags();
-          Constant *C = ConstantExpr::getBinOpIdentity(
-              FVI->getOpcode(), FVI->getType(), true, FMF.noSignedZeros());
-          Value *OOp = FVI->getOperand(2-OpToFold);
-          // Avoid creating select between 2 constants unless it's selecting
-          // between 0, 1 and -1.
-          const APInt *OOpC;
-          bool OOpIsAPInt = match(OOp, m_APInt(OOpC));
-          if (!isa<Constant>(OOp) ||
-              (OOpIsAPInt && isSelect01(C->getUniqueInteger(), *OOpC))) {
-            Value *NewSel = Builder.CreateSelect(SI.getCondition(), C, OOp);
-            if (isa<FPMathOperator>(&SI))
-              cast<Instruction>(NewSel)->setFastMathFlags(FMF);
-            NewSel->takeName(FVI);
-            BinaryOperator *BO = BinaryOperator::Create(FVI->getOpcode(),
-                                                        TrueVal, NewSel);
-            BO->copyIRFlags(FVI);
-            return BO;
-          }
-        }
-      }
-    }
-  }
+  if (Instruction *R = TryFoldSelectIntoOp(SI, FalseVal, TrueVal, true))
+    return R;
 
   return nullptr;
 }