[InstCombine] move code to remove repeated constant check; NFCI

Also, consolidate tests for this fold in one place.

llvm-svn: 315745

1 files changed, 7 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 22538b4..2962300a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -960,10 +960,15 @@ Instruction *InstCombiner::foldAddWithConstant(BinaryOperator &Add) {
     return NV;
 
   Value *X;
-  if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->getScalarSizeInBits() == 1)
-    // zext(bool) + C -> bool ? C + 1 : C
+  // zext(bool) + C -> bool ? C + 1 : C
+  if (match(Op0, m_ZExt(m_Value(X))) &&
+      X->getType()->getScalarSizeInBits() == 1)
     return SelectInst::Create(X, AddOne(Op1C), Op1);
 
+  // ~X + C --> (C-1) - X
+  if (match(Op0, m_Not(m_Value(X))))
+    return BinaryOperator::CreateSub(SubOne(Op1C), X);
+
   const APInt *C;
   if (!match(Op1, m_APInt(C)))
     return nullptr;
@@ -1117,12 +1122,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
   if (haveNoCommonBitsSet(LHS, RHS, DL, &AC, &I, &DT))
     return BinaryOperator::CreateOr(LHS, RHS);
 
-  if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
-    Value *X;
-    if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
-      return BinaryOperator::CreateSub(SubOne(CRHS), X);
-  }
-
   // FIXME: We already did a check for ConstantInt RHS above this.
   // FIXME: Is this pattern covered by another fold? No regression tests fail on
   // removal.