From 53bdccfd619a08f348304e0f773072d7f8f7539d Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Sun, 15 Oct 2017 15:39:15 +0000 Subject: [PATCH] revert r314984: revert r314698 - [InstCombine] remove one-use restriction for icmp (shr exact X, C1), C2 --> icmp X, (C2<> 1 == 2 --> (X & 4) == 4. Constant *ShiftedCmpRHS = ConstantInt::get(ShrTy, C << ShAmtVal); - if (Shr->hasOneUse()) { - if (Shr->isExact()) - return new ICmpInst(Pred, X, ShiftedCmpRHS); + if (Shr->isExact()) + return new ICmpInst(Pred, X, ShiftedCmpRHS); - // Otherwise strength reduce the shift into an 'and'. + if (Shr->hasOneUse()) { + // Canonicalize the shift into an 'and': + // icmp eq/ne (shr X, ShAmt), C --> icmp eq/ne (and X, HiMask), (C << ShAmt) APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); Constant *Mask = ConstantInt::get(ShrTy, Val); Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask"); diff --git a/test/Transforms/InstCombine/icmp-shr.ll b/test/Transforms/InstCombine/icmp-shr.ll index 77eaf09eb96..214f315f317 100644 --- a/test/Transforms/InstCombine/icmp-shr.ll +++ b/test/Transforms/InstCombine/icmp-shr.ll @@ -483,7 +483,7 @@ declare void @foo(i32) define i1 @exact_multiuse(i32 %x) { ; CHECK-LABEL: @exact_multiuse( ; CHECK-NEXT: [[SH:%.*]] = lshr exact i32 %x, 7 -; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[SH]], 1024 +; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 %x, 131072 ; CHECK-NEXT: call void @foo(i32 [[SH]]) ; CHECK-NEXT: ret i1 [[CMP]] ; -- 2.40.0