[InstCombine] add peekThroughBitcast() helper; NFC

This is an NFC portion of D33517. We have similar helpers in the backend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@306008 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index e2eb2ba5d42df0831f2bd763cfd16642d1762a8f..2de83a01062b9ee333898a7562005f9000c7d74b 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1615,12 +1615,8 @@ static Value *matchSelectFromAndOr(Value *A, Value *C, Value *B, Value *D,
   // The potential condition of the select may be bitcasted. In that case, look
   // through its bitcast and the corresponding bitcast of the 'not' condition.
   Type *OrigType = A->getType();
-  Value *SrcA, *SrcB;
-  if (match(A, m_OneUse(m_BitCast(m_Value(SrcA)))) &&
-      match(B, m_OneUse(m_BitCast(m_Value(SrcB))))) {
-    A = SrcA;
-    B = SrcB;
-  }
+  A = peekThroughBitcast(A, true);
+  B = peekThroughBitcast(B, true);
 
   if (Value *Cond = getSelectCondition(A, B, Builder)) {
     // ((bc Cond) & C) | ((bc ~Cond) & D) --> bc (select Cond, (bc C), (bc D))

diff --git a/lib/Transforms/InstCombine/InstCombineInternal.h b/lib/Transforms/InstCombine/InstCombineInternal.h
index a02f1f0fdee078085cf0c1a06b1bc3f7c28ef746..7f0539e52b404ddc92760bd5d4e6f15f8b7bdb70 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -95,6 +95,18 @@ static inline bool isCanonicalPredicate(CmpInst::Predicate Pred) {
   }
 }
 
+/// Return the source operand of a potentially bitcasted value while optionally
+/// checking if it has one use. If there is no bitcast or the one use check is
+/// not met, return the input value itself.
+static inline Value *peekThroughBitcast(Value *V, bool OneUseOnly = false) {
+  if (auto *BitCast = dyn_cast<BitCastInst>(V))
+    if (!OneUseOnly || BitCast->hasOneUse())
+      return BitCast->getOperand(0);
+
+  // V is not a bitcast or V has more than one use and OneUseOnly is true.
+  return V;
+}
+
 /// \brief Add one to a Constant
 static inline Constant *AddOne(Constant *C) {
   return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));