diff options
| -rw-r--r-- | lib/Transforms/InstCombine/InstructionCombining.cpp | 24 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/getelementptr.ll | 20 |
2 files changed, 33 insertions, 11 deletions
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp index 74df1a947c..b4a2e2a1d2 100644 --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -737,7 +737,15 @@ Type *InstCombiner::FindElementAtOffset(Type *Ty, int64_t Offset, return Ty; } - +static bool shouldMergeGEPs(GEPOperator &GEP, GEPOperator &Src) { + // If this GEP has only 0 indices, it is the same pointer as + // Src. If Src is not a trivial GEP too, don't combine + // the indices. + if (GEP.hasAllZeroIndices() && !Src.hasAllZeroIndices() && + !Src.hasOneUse()) + return false; + return true; +} Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end()); @@ -785,21 +793,15 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // getelementptr instructions into a single instruction. // if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) { - - // If this GEP has only 0 indices, it is the same pointer as - // Src. If Src is not a trivial GEP too, don't combine - // the indices. - if (GEP.hasAllZeroIndices() && !Src->hasAllZeroIndices() && - !Src->hasOneUse()) + if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src)) return 0; // Note that if our source is a gep chain itself that we wait for that // chain to be resolved before we perform this transformation. This // avoids us creating a TON of code in some cases. - // - if (GetElementPtrInst *SrcGEP = - dyn_cast<GetElementPtrInst>(Src->getOperand(0))) - if (SrcGEP->getNumOperands() == 2) + if (GEPOperator *SrcGEP = + dyn_cast<GEPOperator>(Src->getOperand(0))) + if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP)) return 0; // Wait until our source is folded to completion. SmallVector<Value*, 8> Indices; diff --git a/test/Transforms/InstCombine/getelementptr.ll b/test/Transforms/InstCombine/getelementptr.ll index 26c0e47f4b..1c120ecbe9 100644 --- a/test/Transforms/InstCombine/getelementptr.ll +++ b/test/Transforms/InstCombine/getelementptr.ll @@ -472,3 +472,23 @@ entry: ; CHECK: @pr10322_f1 ; CHECK: %tmp2 = getelementptr inbounds %pr10322_t* %arrayidx8, i64 0, i32 0 } + +; Test that we combine the last two geps in this sequence, before we +; would wait for gep1 and gep2 to be combined and never combine 2 and 3. +%three_gep_t = type {i32} +%three_gep_t2 = type {%three_gep_t} + +define void @three_gep_f(%three_gep_t2* %x) { + %gep1 = getelementptr %three_gep_t2* %x, i64 2 + call void @three_gep_h(%three_gep_t2* %gep1) + %gep2 = getelementptr %three_gep_t2* %gep1, i64 0, i32 0 + %gep3 = getelementptr %three_gep_t* %gep2, i64 0, i32 0 + call void @three_gep_g(i32* %gep3) + +; CHECK: @three_gep_f +; CHECK: %gep3 = getelementptr %three_gep_t2* %gep1, i64 0, i32 0, i32 0 + ret void +} + +declare void @three_gep_g(i32*) +declare void @three_gep_h(%three_gep_t2*) |