[llvm] r209067 - Revert r209049 and r209065, "Add support for combining GEPs across PHI nodes"
Rafael Espíndola
rafael.espindola at gmail.com
Sat May 17 11:43:29 PDT 2014
Thanks! I was just in the process of reducing a testcase for it. A
testcase is attached.
It should crash with
opt -instcombine test2.bc
On 17 May 2014 10:39, NAKAMURA Takumi <geek4civic at gmail.com> wrote:
> Author: chapuni
> Date: Sat May 17 09:39:21 2014
> New Revision: 209067
>
> URL: http://llvm.org/viewvc/llvm-project?rev=209067&view=rev
> Log:
> Revert r209049 and r209065, "Add support for combining GEPs across PHI nodes"
>
> It broke clang selfhosting even after r209065.
>
> Removed:
> llvm/trunk/test/Transforms/InstCombine/gepphigep.ll
> Modified:
> llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=209067&r1=209066&r2=209067&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Sat May 17 09:39:21 2014
> @@ -1220,72 +1220,6 @@ Instruction *InstCombiner::visitGetEleme
> if (MadeChange) return &GEP;
> }
>
> - // Check to see if the inputs to the PHI node are getelementptr instructions.
> - if (PHINode *PN = dyn_cast<PHINode>(PtrOp)) {
> - GetElementPtrInst *Op1 = dyn_cast<GetElementPtrInst>(PN->getOperand(0));
> - if (!Op1)
> - return nullptr;
> -
> - signed DI = -1;
> -
> - for (auto I = PN->op_begin()+1, E = PN->op_end(); I !=E; ++I) {
> - GetElementPtrInst *Op2 = dyn_cast<GetElementPtrInst>(*I);
> - if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands())
> - return nullptr;
> -
> - for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
> - if (Op1->getOperand(J)->getType() != Op2->getOperand(J)->getType())
> - return nullptr;
> -
> - if (Op1->getOperand(J) != Op2->getOperand(J)) {
> - if (DI == -1) {
> - // We have not seen any differences yet in the GEPs feeding the
> - // PHI yet, so we record this one.
> - DI = J;
> - } else {
> - // The GEP is different by more than one input. While this could be
> - // extended to support GEPs that vary by more than one variable it
> - // doesn't make sense since it greatly increases the complexity and
> - // would result in an R+R+R addressing mode which no backend
> - // directly supports and would need to be broken into several
> - // simpler instructions anyway.
> - return nullptr;
> - }
> - }
> - }
> - }
> -
> - GetElementPtrInst *NewGEP = dyn_cast<GetElementPtrInst>(Op1->clone());
> -
> - if (DI == -1) {
> - // All the GEPs feeding the PHI are identical. Clone one down into our
> - // BB so that it can be merged with the current GEP.
> - GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
> - NewGEP);
> - } else {
> - // All the GEPs feeding the PHI differ at a single offset. Clone a GEP
> - // into the current block so it can be merged, and create a new PHI to
> - // set that index.
> - Instruction *InsertPt = Builder->GetInsertPoint();
> - Builder->SetInsertPoint(PN);
> - PHINode *NewPN = Builder->CreatePHI(Op1->getOperand(DI)->getType(),
> - PN->getNumOperands());
> - Builder->SetInsertPoint(InsertPt);
> -
> - for (auto &I : PN->operands())
> - NewPN->addIncoming(dyn_cast<GEPOperator>(I)->getOperand(DI),
> - PN->getIncomingBlock(I));
> -
> - NewGEP->setOperand(DI, NewPN);
> - GEP.getParent()->getInstList().insert(GEP.getParent()->getFirstNonPHI(),
> - NewGEP);
> - NewGEP->setOperand(DI, NewPN);
> - }
> -
> - GEP.setOperand(0, NewGEP);
> - PtrOp = NewGEP;
> - }
> -
> // Combine Indices - If the source pointer to this getelementptr instruction
> // is a getelementptr instruction, combine the indices of the two
> // getelementptr instructions into a single instruction.
>
> Removed: llvm/trunk/test/Transforms/InstCombine/gepphigep.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/gepphigep.ll?rev=209066&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/InstCombine/gepphigep.ll (original)
> +++ llvm/trunk/test/Transforms/InstCombine/gepphigep.ll (removed)
> @@ -1,56 +0,0 @@
> -; RUN: opt -instcombine -S < %s | FileCheck %s
> -
> -%struct1 = type { %struct2*, i32, i32, i32 }
> -%struct2 = type { i32, i32 }
> -
> -define i32 @test1(%struct1* %dm, i1 %tmp4, i64 %tmp9, i64 %tmp19) {
> -bb:
> - %tmp = getelementptr inbounds %struct1* %dm, i64 0, i32 0
> - %tmp1 = load %struct2** %tmp, align 8
> - br i1 %tmp4, label %bb1, label %bb2
> -
> -bb1:
> - %tmp10 = getelementptr inbounds %struct2* %tmp1, i64 %tmp9
> - %tmp11 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 0
> - store i32 0, i32* %tmp11, align 4
> - br label %bb3
> -
> -bb2:
> - %tmp20 = getelementptr inbounds %struct2* %tmp1, i64 %tmp19
> - %tmp21 = getelementptr inbounds %struct2* %tmp20, i64 0, i32 0
> - store i32 0, i32* %tmp21, align 4
> - br label %bb3
> -
> -bb3:
> - %phi = phi %struct2* [ %tmp10, %bb1 ], [ %tmp20, %bb2 ]
> - %tmp24 = getelementptr inbounds %struct2* %phi, i64 0, i32 1
> - %tmp25 = load i32* %tmp24, align 4
> - ret i32 %tmp25
> -
> -; CHECK-LABEL: @test1(
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 0
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp19, i32 0
> -; CHECK: %[[PHI:[0-9A-Za-z]+]] = phi i64 [ %tmp9, %bb1 ], [ %tmp19, %bb2 ]
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %[[PHI]], i32 1
> -}
> -
> -define i32 @test2(%struct1* %dm, i1 %tmp4, i64 %tmp9, i64 %tmp19) {
> -bb:
> - %tmp = getelementptr inbounds %struct1* %dm, i64 0, i32 0
> - %tmp1 = load %struct2** %tmp, align 8
> - %tmp10 = getelementptr inbounds %struct2* %tmp1, i64 %tmp9
> - %tmp11 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 0
> - store i32 0, i32* %tmp11, align 4
> - %tmp20 = getelementptr inbounds %struct2* %tmp1, i64 %tmp19
> - %tmp21 = getelementptr inbounds %struct2* %tmp20, i64 0, i32 0
> - store i32 0, i32* %tmp21, align 4
> - %tmp24 = getelementptr inbounds %struct2* %tmp10, i64 0, i32 1
> - %tmp25 = load i32* %tmp24, align 4
> - ret i32 %tmp25
> -
> -; CHECK-LABEL: @test2(
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 0
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp19, i32 0
> -; CHECK: getelementptr inbounds %struct2* %tmp1, i64 %tmp9, i32 1
> -}
> -
>
>
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