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Fix (hopefully the last) issue where LSR is nondeterminstic. When pulling

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out CSE's of base expressions it could build a result whose order was
nondet.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23698 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-11 18:41:04 +00:00
parent 7b445c521b
commit d6155e96f7
1 changed files with 14 additions and 8 deletions
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22
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -715,6 +715,10 @@ RemoveCommonExpressionsFromUseBases(std::vector<BasedUser> &Uses) {
// If any subexpressions are used Uses.size() times, they are common.
std::map<SCEVHandle, unsigned> SubExpressionUseCounts;
// UniqueSubExprs - Keep track of all of the subexpressions we see in the
// order we see them.
std::vector<SCEVHandle> UniqueSubExprs;
std::vector<SCEVHandle> SubExprs;
for (unsigned i = 0; i != NumUses; ++i) {
// If the base is zero (which is common), return zero now, there are no
@ -725,22 +729,24 @@ RemoveCommonExpressionsFromUseBases(std::vector<BasedUser> &Uses) {
SeparateSubExprs(SubExprs, Uses[i].Base);
// Add one to SubExpressionUseCounts for each subexpr present.
for (unsigned j = 0, e = SubExprs.size(); j != e; ++j)
SubExpressionUseCounts[SubExprs[j]]++;
if (++SubExpressionUseCounts[SubExprs[j]] == 1)
UniqueSubExprs.push_back(SubExprs[j]);
SubExprs.clear();
}
// Now that we know how many times each is used, build Result.
for (std::map<SCEVHandle, unsigned>::iterator I =
SubExpressionUseCounts.begin(), E = SubExpressionUseCounts.end();
I != E; )
// Now that we know how many times each is used, build Result. Iterate over
// UniqueSubexprs so that we have a stable ordering.
for (unsigned i = 0, e = UniqueSubExprs.size(); i != e; ++i) {
std::map<SCEVHandle, unsigned>::iterator I =
SubExpressionUseCounts.find(UniqueSubExprs[i]);
assert(I != SubExpressionUseCounts.end() && "Entry not found?");
if (I->second == NumUses) { // Found CSE!
Result = SCEVAddExpr::get(Result, I->first);
++I;
} else {
// Remove non-cse's from SubExpressionUseCounts.
SubExpressionUseCounts.erase(I++);
SubExpressionUseCounts.erase(I);
}
}
// If we found no CSE's, return now.
if (Result == Zero) return Result;