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SCEV validator: Add workarounds for some common false positives due to the way it handles strings.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166872 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2012-10-27 10:45:01 +00:00
parent d62fd65e72
commit cb8b8ea2b6
1 changed files with 18 additions and 0 deletions
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18
lib/Analysis/ScalarEvolution.cpp
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@ -6941,6 +6941,16 @@ void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
}
typedef DenseMap<const Loop *, std::string> VerifyMap;
/// replaceSubString - Replaces all occurences of From in Str with To.
static void replaceSubString(std::string &Str, StringRef From, StringRef To) {
size_t Pos = 0;
while ((Pos = Str.find(From, Pos)) != std::string::npos) {
Str.replace(Pos, From.size(), To.data(), To.size());
Pos += To.size();
}
}
/// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis.
static void
getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) {
@ -6951,6 +6961,14 @@ getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map, ScalarEvolution &SE) {
if (S.empty()) {
raw_string_ostream OS(S);
SE.getBackedgeTakenCount(L)->print(OS);
// false and 0 are semantically equivalent. This can happen in dead loops.
replaceSubString(OS.str(), "false", "0");
// Remove wrap flags, their use in SCEV is highly fragile.
// FIXME: Remove this when SCEV gets smarter about them.
replaceSubString(OS.str(), "<nw>", "");
replaceSubString(OS.str(), "<nsw>", "");
replaceSubString(OS.str(), "<nuw>", "");
}
}
}