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[InstCombine] Add optimization of redundant insertvalue instructions.

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rdar://problem/11861387

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208214 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Zolotukhin 2014-05-07 14:30:18 +00:00
parent 0c78010b88
commit 355e0a6460
3 changed files with 62 additions and 0 deletions
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1
lib/Transforms/InstCombine/InstCombine.h
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@ -211,6 +211,7 @@ public:
Instruction *visitStoreInst(StoreInst &SI);
Instruction *visitBranchInst(BranchInst &BI);
Instruction *visitSwitchInst(SwitchInst &SI);
Instruction *visitInsertValueInst(InsertValueInst &IV);
Instruction *visitInsertElementInst(InsertElementInst &IE);
Instruction *visitExtractElementInst(ExtractElementInst &EI);
Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);

36
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
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@ -490,6 +490,42 @@ static ShuffleOps CollectShuffleElements(Value *V,
return std::make_pair(V, nullptr);
}
/// Try to find redundant insertvalue instructions, like the following ones:
/// %0 = insertvalue { i8, i32 } undef, i8 %x, 0
/// %1 = insertvalue { i8, i32 } %0, i8 %y, 0
/// Here the second instruction inserts values at the same indices, as the
/// first one, making the first one redundant.
/// It should be transformed to:
/// %0 = insertvalue { i8, i32 } undef, i8 %y, 0
Instruction *InstCombiner::visitInsertValueInst(InsertValueInst &I) {
bool IsRedundant = false;
ArrayRef<unsigned int> FirstIndices = I.getIndices();
// If there is a chain of insertvalue instructions (each of them except the
// last one has only one use and it's another insertvalue insn from this
// chain), check if any of the 'children' uses the same indices as the first
// instruction. In this case, the first one is redundant.
Value *V = &I;
unsigned int Depth = 0;
while (V->hasOneUse() && Depth < 10) {
User *U = V->user_back();
InsertValueInst *UserInsInst = dyn_cast<InsertValueInst>(U);
if (!UserInsInst || U->getType() != I.getType()) {
break;
}
if (UserInsInst->getIndices() == FirstIndices) {
IsRedundant = true;
break;
}
V = UserInsInst;
Depth++;
}
if (IsRedundant)
return ReplaceInstUsesWith(I, I.getOperand(0));
return nullptr;
}
Instruction *InstCombiner::visitInsertElementInst(InsertElementInst &IE) {
Value *VecOp = IE.getOperand(0);
Value *ScalarOp = IE.getOperand(1);

25
test/Transforms/InstCombine/OverlappingInsertvalues.ll Normal file
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@ -0,0 +1,25 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
; Check that we can find and remove redundant insertvalues
; CHECK-LABEL: foo_simple
; CHECK-NOT: i8* %x, 0
define { i8*, i64, i32 } @foo_simple(i8* %x, i8* %y) nounwind {
entry:
%0 = insertvalue { i8*, i64, i32 } undef, i8* %x, 0
%1 = insertvalue { i8*, i64, i32 } %0, i8* %y, 0
ret { i8*, i64, i32 } %1
}
; Check that we can find and remove redundant nodes in insertvalues chain
; CHECK-LABEL: foo_ovwrt_chain
; CHECK-NOT: i64 %y, 1
; CHECK-NOT: i32 555, 2
define { i8*, i64, i32 } @foo_ovwrt_chain(i8* %x, i64 %y, i64 %z) nounwind {
entry:
%0 = insertvalue { i8*, i64, i32 } undef, i8* %x, 0
%1 = insertvalue { i8*, i64, i32 } %0, i64 %y, 1
%2 = insertvalue { i8*, i64, i32 } %1, i32 555, 2
%3 = insertvalue { i8*, i64, i32 } %2, i64 %z, 1
%4 = insertvalue { i8*, i64, i32 } %3, i32 777, 2
ret { i8*, i64, i32 } %4
}