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[InstCombine] Use replaceOperand() API in GEP transforms 

To make sure that replaced operands get DCEd. This drops one
iteration from gepphigep.ll, which is still not optimal.

This was the last test case performing more than 3 iterations.

NFC-ish, only worklist order should change.
This commit is contained in:
Nikita Popov 2020-03-28 19:02:48 +01:00
parent b1f78baeaa
commit 30d712103f
2 changed files with 5 additions and 6 deletions
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9
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -1996,7 +1996,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
GEP.getParent()->getInstList().insert(
GEP.getParent()->getFirstInsertionPt(), NewGEP);
GEP.setOperand(0, NewGEP);
replaceOperand(GEP, 0, NewGEP);
PtrOp = NewGEP;
}
@ -2096,8 +2096,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// Update the GEP in place if possible.
if (Src->getNumOperands() == 2) {
GEP.setIsInBounds(isMergedGEPInBounds(*Src, *cast<GEPOperator>(&GEP)));
GEP.setOperand(0, Src->getOperand(0));
GEP.setOperand(1, Sum);
replaceOperand(GEP, 0, Src->getOperand(0));
replaceOperand(GEP, 1, Sum);
return &GEP;
}
Indices.append(Src->op_begin()+1, Src->op_end()-1);
@ -2215,9 +2215,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
// array. Because the array type is never stepped over (there
// is a leading zero) we can fold the cast into this GEP.
if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
GEP.setOperand(0, StrippedPtr);
GEP.setSourceElementType(XATy);
return &GEP;
return replaceOperand(GEP, 0, StrippedPtr);
}
// Cannot replace the base pointer directly because StrippedPtr's
// address space is different. Instead, create a new GEP followed by

2
llvm/test/Transforms/InstCombine/gepphigep.ll
View File

@ -1,4 +1,4 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
; RUN: opt -instcombine -instcombine-infinite-loop-threshold=3 -S < %s | FileCheck %s
%struct1 = type { %struct2*, i32, i32, i32 }
%struct2 = type { i32, i32 }