[llvm] r306008 - [InstCombine] add peekThroughBitcast() helper; NFC

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Thu Jun 22 10:28:01 2017
New Revision: 306008

URL: http://llvm.org/viewvc/llvm-project?rev=306008&view=rev
Log:
[InstCombine] add peekThroughBitcast() helper; NFC

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

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=306008&r1=306007&r2=306008&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Thu Jun 22 10:28:01 2017
@@ -1615,12 +1615,8 @@ static Value *matchSelectFromAndOr(Value
   // 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))

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=306008&r1=306007&r2=306008&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Thu Jun 22 10:28:01 2017
@@ -95,6 +95,18 @@ static inline bool isCanonicalPredicate(
   }
 }
 
+/// 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));