[InstCombine] refactor mul narrowing folds; NFCI
Similar to rL342278:
The test diffs are all cosmetic due to the change in
value naming, but I'm including that to show that the
new code does perform these folds rather than something
else in instcombine.
D52075 should be able to use this code too rather than
duplicating all of the logic.
llvm-svn: 342292
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index ee21363..d76351f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -322,77 +322,8 @@
if (match(Op1, m_LShr(m_Value(X), m_APInt(C))) && *C == C->getBitWidth() - 1)
return BinaryOperator::CreateAnd(Builder.CreateAShr(X, *C), Op0);
- // Check for (mul (sext x), y), see if we can merge this into an
- // integer mul followed by a sext.
- if (SExtInst *Op0Conv = dyn_cast<SExtInst>(Op0)) {
- // (mul (sext x), cst) --> (sext (mul x, cst'))
- if (auto *Op1C = dyn_cast<Constant>(Op1)) {
- if (Op0Conv->hasOneUse()) {
- Constant *CI =
- ConstantExpr::getTrunc(Op1C, Op0Conv->getOperand(0)->getType());
- if (ConstantExpr::getSExt(CI, I.getType()) == Op1C &&
- willNotOverflowSignedMul(Op0Conv->getOperand(0), CI, I)) {
- // Insert the new, smaller mul.
- Value *NewMul =
- Builder.CreateNSWMul(Op0Conv->getOperand(0), CI, "mulconv");
- return new SExtInst(NewMul, I.getType());
- }
- }
- }
-
- // (mul (sext x), (sext y)) --> (sext (mul int x, y))
- if (SExtInst *Op1Conv = dyn_cast<SExtInst>(Op1)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of sexts), and if the
- // integer mul will not overflow.
- if (Op0Conv->getOperand(0)->getType() ==
- Op1Conv->getOperand(0)->getType() &&
- (Op0Conv->hasOneUse() || Op1Conv->hasOneUse()) &&
- willNotOverflowSignedMul(Op0Conv->getOperand(0),
- Op1Conv->getOperand(0), I)) {
- // Insert the new integer mul.
- Value *NewMul = Builder.CreateNSWMul(
- Op0Conv->getOperand(0), Op1Conv->getOperand(0), "mulconv");
- return new SExtInst(NewMul, I.getType());
- }
- }
- }
-
- // Check for (mul (zext x), y), see if we can merge this into an
- // integer mul followed by a zext.
- if (auto *Op0Conv = dyn_cast<ZExtInst>(Op0)) {
- // (mul (zext x), cst) --> (zext (mul x, cst'))
- if (auto *Op1C = dyn_cast<Constant>(Op1)) {
- if (Op0Conv->hasOneUse()) {
- Constant *CI =
- ConstantExpr::getTrunc(Op1C, Op0Conv->getOperand(0)->getType());
- if (ConstantExpr::getZExt(CI, I.getType()) == Op1C &&
- willNotOverflowUnsignedMul(Op0Conv->getOperand(0), CI, I)) {
- // Insert the new, smaller mul.
- Value *NewMul =
- Builder.CreateNUWMul(Op0Conv->getOperand(0), CI, "mulconv");
- return new ZExtInst(NewMul, I.getType());
- }
- }
- }
-
- // (mul (zext x), (zext y)) --> (zext (mul int x, y))
- if (auto *Op1Conv = dyn_cast<ZExtInst>(Op1)) {
- // Only do this if x/y have the same type, if at last one of them has a
- // single use (so we don't increase the number of zexts), and if the
- // integer mul will not overflow.
- if (Op0Conv->getOperand(0)->getType() ==
- Op1Conv->getOperand(0)->getType() &&
- (Op0Conv->hasOneUse() || Op1Conv->hasOneUse()) &&
- willNotOverflowUnsignedMul(Op0Conv->getOperand(0),
- Op1Conv->getOperand(0), I)) {
- // Insert the new integer mul.
- Value *NewMul = Builder.CreateNUWMul(
- Op0Conv->getOperand(0), Op1Conv->getOperand(0), "mulconv");
- return new ZExtInst(NewMul, I.getType());
- }
- }
- }
+ if (Instruction *Ext = narrowMathIfNoOverflow(I))
+ return Ext;
bool Changed = false;
if (!I.hasNoSignedWrap() && willNotOverflowSignedMul(Op0, Op1, I)) {