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Fix one source of nondeterminism in the -licm pass: the hoist pass

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was processing blocks in whatever order they happened to end up in the
dominator tree data structure.  Force an ordering.

llvm-svn: 14248
This commit is contained in:
Chris Lattner 2004-06-19 08:56:43 +00:00
parent d2720878ec
commit 185f2b060b
1 changed files with 16 additions and 2 deletions
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18
lib/Transforms/Scalar/LICM.cpp
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@ -40,6 +40,7 @@
#include "llvm/Analysis/AliasSetTracker.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/StableBasicBlockNumbering.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include "llvm/Transforms/Utils/Local.h"
#include "Support/CommandLine.h"
@ -81,6 +82,7 @@ namespace {
LoopInfo *LI; // Current LoopInfo
DominatorTree *DT; // Dominator Tree for the current Loop...
DominanceFrontier *DF; // Current Dominance Frontier
StableBasicBlockNumbering *BBNum; // Stable IDs for basic blocks
// State that is updated as we process loops
bool Changed; // Set to true when we change anything.
@ -203,7 +205,7 @@ FunctionPass *llvm::createLICMPass() { return new LICM(); }
/// runOnFunction - For LICM, this simply traverses the loop structure of the
/// function, hoisting expressions out of loops if possible.
///
bool LICM::runOnFunction(Function &) {
bool LICM::runOnFunction(Function &F) {
Changed = false;
// Get our Loop and Alias Analysis information...
@ -212,6 +214,10 @@ bool LICM::runOnFunction(Function &) {
DF = &getAnalysis<DominanceFrontier>();
DT = &getAnalysis<DominatorTree>();
// Get a stable numbering of basic blocks.
StableBasicBlockNumbering CurBBNum(&F);
BBNum = &CurBBNum;
// Hoist expressions out of all of the top-level loops.
for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I) {
AliasSetTracker AST(*AA);
@ -337,8 +343,16 @@ void LICM::HoistRegion(DominatorTree::Node *N) {
}
const std::vector<DominatorTree::Node*> &Children = N->getChildren();
std::vector<std::pair<unsigned, DominatorTree::Node*> > ChildrenWithIDs;
ChildrenWithIDs.reserve(Children.size());
for (unsigned i = 0, e = Children.size(); i != e; ++i) {
unsigned ID = BBNum->getNumber(Children[i]->getBlock());
ChildrenWithIDs.push_back(std::make_pair(ID, Children[i]));
}
std::sort(ChildrenWithIDs.begin(), ChildrenWithIDs.end());
for (unsigned i = 0, e = Children.size(); i != e; ++i)
HoistRegion(Children[i]);
HoistRegion(ChildrenWithIDs[i].second);
}
/// canSinkOrHoistInst - Return true if the hoister and sinker can handle this