From 7f0d69555caab5f5468ddf74b5840f59c4c6fd83 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Fri, 14 May 2010 22:53:18 +0000 Subject: [PATCH] Fast ISel trivially coalesces away no-op casts, so check for this when setting kill flags. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103832 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/FastISel.cpp | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp index 253ceca15eb..1996c192ec7 100644 --- a/lib/CodeGen/SelectionDAG/FastISel.cpp +++ b/lib/CodeGen/SelectionDAG/FastISel.cpp @@ -57,11 +57,23 @@ using namespace llvm; bool FastISel::hasTrivialKill(const Value *V) const { - // Don't consider constants or arguments to have trivial kills. Only - // instructions with a single use in the same basic block. + // Don't consider constants or arguments to have trivial kills. const Instruction *I = dyn_cast(V); - return I && - I->hasOneUse() && + if (!I) + return false; + + // No-op casts are trivially coalesced by fast-isel. + if (const CastInst *Cast = dyn_cast(I)) + if (Cast->isNoopCast(TD.getIntPtrType(Cast->getContext())) && + !hasTrivialKill(Cast->getOperand(0))) + return false; + + // Only instructions with a single use in the same basic block are considered + // to have trivial kills. + return I->hasOneUse() && + !(I->getOpcode() == Instruction::BitCast || + I->getOpcode() == Instruction::PtrToInt || + I->getOpcode() == Instruction::IntToPtr) && cast(I->use_begin())->getParent() == I->getParent(); } -- 2.34.1