diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index bf287f2c680..5bd17e0737b 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -8564,20 +8564,33 @@ Instruction *InstCombiner::visitZExt(ZExtInst &CI) { } } - // zext(trunc(t) & C) -> (t & C) if C is a mask. + // zext(trunc(t) & C) -> (t & zext(C)). if (SrcI && SrcI->getOpcode() == Instruction::And && SrcI->hasOneUse()) if (ConstantInt *C = dyn_cast(SrcI->getOperand(1))) if (TruncInst *TI = dyn_cast(SrcI->getOperand(0))) { Value *TI0 = TI->getOperand(0); - if (TI0->getType() == CI.getType()) { - unsigned TO = C->getValue().countTrailingOnes(); - if (APIntOps::isMask(TO, C->getValue())) - return - BinaryOperator::Create(Instruction::And, TI0, - ConstantExpr::getZExt(C, CI.getType())); - } + if (TI0->getType() == CI.getType()) + return + BinaryOperator::CreateAnd(TI0, + ConstantExpr::getZExt(C, CI.getType())); } + // zext((trunc(t) & C) ^ C) -> ((t & zext(C)) ^ zext(C)). + if (SrcI && SrcI->getOpcode() == Instruction::Xor && SrcI->hasOneUse()) + if (ConstantInt *C = dyn_cast(SrcI->getOperand(1))) + if (BinaryOperator *And = dyn_cast(SrcI->getOperand(0))) + if (And->getOpcode() == Instruction::And && And->hasOneUse() && + And->getOperand(1) == C) + if (TruncInst *TI = dyn_cast(And->getOperand(0))) { + Value *TI0 = TI->getOperand(0); + if (TI0->getType() == CI.getType()) { + Constant *ZC = ConstantExpr::getZExt(C, CI.getType()); + Instruction *NewAnd = BinaryOperator::CreateAnd(TI0, ZC, "tmp"); + InsertNewInstBefore(NewAnd, *And); + return BinaryOperator::CreateXor(NewAnd, ZC); + } + } + return 0; } diff --git a/test/Transforms/InstCombine/trunc-mask-ext.ll b/test/Transforms/InstCombine/trunc-mask-ext.ll index 1499947cc07..7e3d8446acf 100644 --- a/test/Transforms/InstCombine/trunc-mask-ext.ll +++ b/test/Transforms/InstCombine/trunc-mask-ext.ll @@ -2,7 +2,7 @@ ; RUN: not grep zext %t ; RUN: not grep sext %t -; Instcombine should be able to eliminate both ext casts. +; Instcombine should be able to eliminate all of these ext casts. declare void @use(i32) @@ -21,3 +21,18 @@ define i64 @bar(i64 %a) { call void @use(i32 %b) ret i64 %d } +define i64 @goo(i64 %a) { + %b = trunc i64 %a to i32 + %c = and i32 %b, 8 + %d = zext i32 %c to i64 + call void @use(i32 %b) + ret i64 %d +} +define i64 @hoo(i64 %a) { + %b = trunc i64 %a to i32 + %c = and i32 %b, 8 + %x = xor i32 %c, 8 + %d = zext i32 %x to i64 + call void @use(i32 %b) + ret i64 %d +}