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PHI nodes were incorrectly placed when more than one GEP is reduced in a loop.

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llvm-svn: 20360
This commit is contained in:
Jeff Cohen 2005-02-27 21:08:04 +00:00
parent 6258d4a431
commit fd9504c7d9
1 changed files with 6 additions and 7 deletions
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13
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -99,7 +99,8 @@ void LoopStrengthReduce::strengthReduceGEP(GetElementPtrInst *GEPI, Loop *L,
// GEP.
//
// We currently only handle GEP instructions that consist of zero or more
// constants and one instance of the canonical induction variable.
// constants or loop invariable expressions prior to an instance of the
// canonical induction variable.
unsigned indvar = 0;
std::vector<Value *> pre_op_vector;
std::vector<Value *> inc_op_vector;
@ -208,21 +209,19 @@ void LoopStrengthReduce::runOnLoop(Loop *L) {
if (0 == PN)
return;
// Insert secondary PHI nodes after the canonical induction variable's PHI
// for the strength reduced pointers that we will be creating.
Instruction *InsertBefore = PN->getNext();
// FIXME: Need to use SCEV to detect GEP uses of the indvar, since indvars
// pass creates code like this, which we can't currently detect:
// %tmp.1 = sub uint 2000, %indvar
// %tmp.8 = getelementptr int* %y, uint %tmp.1
// Strength reduce all GEPs in the Loop
// Strength reduce all GEPs in the Loop. Insert secondary PHI nodes for the
// strength reduced pointers we'll be creating after the canonical induction
// variable's PHI.
std::set<Instruction*> DeadInsts;
for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
UI != UE; ++UI)
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI))
strengthReduceGEP(GEPI, L, InsertBefore, DeadInsts);
strengthReduceGEP(GEPI, L, PN->getNext(), DeadInsts);
// Clean up after ourselves
if (!DeadInsts.empty()) {