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Fix an infinite loop on 300.twolf.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40497 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2007-07-25 22:03:06 +00:00
parent 02d6852a1c
commit 0d16988690
2 changed files with 31 additions and 6 deletions
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21
lib/Transforms/Scalar/GVN.cpp
View File

@ -651,7 +651,8 @@ namespace {
SmallVector<Instruction*, 4>& toErase);
bool processNonLocalLoad(LoadInst* L, SmallVector<Instruction*, 4>& toErase);
Value *performPHIConstruction(BasicBlock *BB, LoadInst* orig,
DenseMap<BasicBlock*, Value*> &Phis);
DenseMap<BasicBlock*, Value*> &Phis,
SmallPtrSet<BasicBlock*, 4>& visited);
void dump(DenseMap<BasicBlock*, Value*>& d);
};
@ -706,7 +707,8 @@ void GVN::dump(DenseMap<BasicBlock*, Value*>& d) {
Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
DenseMap<BasicBlock*, Value*> &Phis) {
DenseMap<BasicBlock*, Value*> &Phis,
SmallPtrSet<BasicBlock*, 4>& visited) {
DenseMap<BasicBlock*, Value*>::iterator DI = Phis.find(BB);
if (DI != Phis.end())
return DI->second;
@ -719,7 +721,10 @@ Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
Phis.insert(std::make_pair(BB, DI->second));
return DI->second;
} else {
Value* domV = performPHIConstruction(*pred_begin(BB), orig, Phis);
visited.insert(BB);
Value* domV = performPHIConstruction(*pred_begin(BB), orig, Phis, visited);
visited.erase(BB);
Phis.insert(std::make_pair(BB, domV));
return domV;
}
@ -727,9 +732,14 @@ Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
PHINode *PN = new PHINode(orig->getType(), orig->getName()+".rle", BB->begin());
PN->reserveOperandSpace(numPreds);
visited.insert(BB);
// Fill in the incoming values for the block.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
PN->addIncoming(performPHIConstruction(*PI, orig, Phis), *PI);
if (!visited.count(*PI))
PN->addIncoming(performPHIConstruction(*PI, orig, Phis, visited), *PI);
else
PN->addIncoming(PN, *PI);
visited.erase(BB);
bool all_same = PN->getNumIncomingValues() != 1;
Value* first = PN->getIncomingValue(0);
@ -772,7 +782,8 @@ bool GVN::processNonLocalLoad(LoadInst* L, SmallVector<Instruction*, 4>& toErase
return false;
}
Value* v = performPHIConstruction(L->getParent(), L, repl);
SmallPtrSet<BasicBlock*, 4> visited;
Value* v = performPHIConstruction(L->getParent(), L, repl, visited);
MD.removeInstruction(L);
L->replaceAllUsesWith(v);

14
test/Transforms/GVN/2007-07-25-InfiniteLoop.ll Normal file
View File

@ -0,0 +1,14 @@
; RUN: llvm-as < %s | opt -gvn | llvm-dis
%struct.INT2 = type { i32, i32 }
@blkshifts = external global %struct.INT2* ; <%struct.INT2**> [#uses=2]
define i32 @xcompact() {
entry:
store %struct.INT2* null, %struct.INT2** @blkshifts, align 4
br label %bb
bb: ; preds = %bb, %entry
%tmp10 = load %struct.INT2** @blkshifts, align 4 ; <%struct.INT2*> [#uses=0]
br label %bb
}