[PATCH] D34974: [InstCombine] Add single use checks to SimplifyBSwap to ensure we are really saving instructions

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This revision was automatically updated to reflect the committed changes.
Closed by commit rL307273: [InstCombine] Add single use checks to SimplifyBSwap to ensure we are really… (authored by ctopper).

Changed prior to commit:
  https://reviews.llvm.org/D34974?vs=105139&id=105455#toc

Repository:
  rL LLVM

https://reviews.llvm.org/D34974

Files:
  llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
  llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll


Index: llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll
+++ llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll
@@ -285,9 +285,8 @@
 ; CHECK-LABEL: @bs_and64_multiuse1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = tail call i64 @llvm.bswap.i64(i64 [[A:%.*]])
 ; CHECK-NEXT:    [[TMP2:%.*]] = tail call i64 @llvm.bswap.i64(i64 [[B:%.*]])
-; CHECK-NEXT:    [[TMP3:%.*]] = and i64 [[A]], [[B]]
-; CHECK-NEXT:    [[TMP6:%.*]] = call i64 @llvm.bswap.i64(i64 [[TMP3]])
-; CHECK-NEXT:    [[TMP4:%.*]] = mul i64 [[TMP6]], [[TMP1]]
+; CHECK-NEXT:    [[TMP3:%.*]] = and i64 [[TMP1]], [[TMP2]]
+; CHECK-NEXT:    [[TMP4:%.*]] = mul i64 [[TMP3]], [[TMP1]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = mul i64 [[TMP4]], [[TMP2]]
 ; CHECK-NEXT:    ret i64 [[TMP5]]
 ;
@@ -332,9 +331,8 @@
 define i64 @bs_and64i_multiuse(i64 %a, i64 %b) #0 {
 ; CHECK-LABEL: @bs_and64i_multiuse(
 ; CHECK-NEXT:    [[TMP1:%.*]] = tail call i64 @llvm.bswap.i64(i64 [[A:%.*]])
-; CHECK-NEXT:    [[TMP2:%.*]] = and i64 [[A]], 129085117527228416
-; CHECK-NEXT:    [[TMP4:%.*]] = call i64 @llvm.bswap.i64(i64 [[TMP2]])
-; CHECK-NEXT:    [[TMP3:%.*]] = mul i64 [[TMP4]], [[TMP1]]
+; CHECK-NEXT:    [[TMP2:%.*]] = and i64 [[TMP1]], 1000000001
+; CHECK-NEXT:    [[TMP3:%.*]] = mul i64 [[TMP2]], [[TMP1]]
 ; CHECK-NEXT:    ret i64 [[TMP3]]
 ;
   %tmp1 = tail call i64 @llvm.bswap.i64(i64 %a)
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -82,20 +82,25 @@
 Value *InstCombiner::SimplifyBSwap(BinaryOperator &I) {
   assert(I.isBitwiseLogicOp() && "Unexpected opcode for bswap simplifying");
 
-  // TODO We should probably check for single use of the bswap.
+  Value *OldLHS = I.getOperand(0);
+  Value *OldRHS = I.getOperand(1);
 
   Value *NewLHS;
-  if (!match(I.getOperand(0), m_BSwap(m_Value(NewLHS))))
+  if (!match(OldLHS, m_BSwap(m_Value(NewLHS))))
     return nullptr;
 
   Value *NewRHS;
   const APInt *C;
 
-  if (match(I.getOperand(1), m_BSwap(m_Value(NewRHS)))) {
+  if (match(OldRHS, m_BSwap(m_Value(NewRHS)))) {
     // OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
+    if (!OldLHS->hasOneUse() && !OldRHS->hasOneUse())
+      return nullptr;
     // NewRHS initialized by the matcher.
-  } else if (match(I.getOperand(1), m_APInt(C))) {
+  } else if (match(OldRHS, m_APInt(C))) {
     // OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )
+    if (!OldLHS->hasOneUse())
+      return nullptr;
     NewRHS = ConstantInt::get(I.getType(), C->byteSwap());
   } else
     return nullptr;


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