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Assign arguments different ranks so they get grouped together 

llvm-svn: 7813
This commit is contained in:
Chris Lattner 2003-08-13 16:16:26 +00:00
parent cea4d8c2f5
commit 8ac196dd3b
1 changed files with 10 additions and 4 deletions
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14
llvm/lib/Transforms/Scalar/Reassociate.cpp
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@ -37,7 +37,7 @@ namespace {
class Reassociate : public FunctionPass {
std::map<BasicBlock*, unsigned> RankMap;
std::map<Instruction*, unsigned> InstRankMap;
std::map<Value*, unsigned> ValueRankMap;
public:
bool runOnFunction(Function &F);
@ -58,6 +58,11 @@ Pass *createReassociatePass() { return new Reassociate(); }
void Reassociate::BuildRankMap(Function &F) {
unsigned i = 2;
// Assign distinct ranks to function arguments
for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
ValueRankMap[I] = ++i;
ReversePostOrderTraversal<Function*> RPOT(&F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
E = RPOT.end(); I != E; ++I)
@ -65,7 +70,8 @@ void Reassociate::BuildRankMap(Function &F) {
}
unsigned Reassociate::getRank(Value *V) {
if (isa<Argument>(V)) return 1; // Function argument...
if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument...
if (Instruction *I = dyn_cast<Instruction>(V)) {
// If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that
// we can reassociate expressions for code motion! Since we do not recurse
@ -78,7 +84,7 @@ unsigned Reassociate::getRank(Value *V) {
I->mayWriteToMemory()) // Cannot move inst if it writes to memory!
return RankMap[I->getParent()];
unsigned &CachedRank = InstRankMap[I];
unsigned &CachedRank = ValueRankMap[I];
if (CachedRank) return CachedRank; // Rank already known?
// If not, compute it!
@ -278,6 +284,6 @@ bool Reassociate::runOnFunction(Function &F) {
// We are done with the rank map...
RankMap.clear();
InstRankMap.clear();
ValueRankMap.clear();
return Changed;
}