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MergeFunctions Pass, introduced total ordering among function attributes.

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This patch belongs to patch series that improves MergeFunctions
performance time from O(N*N) to O(N*log(N)).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208953 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Stepan Dyatkovskiy 2014-05-16 08:55:34 +00:00
parent fbe77b1c6a
commit 0288fb012c
1 changed files with 36 additions and 0 deletions
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36
lib/Transforms/IPO/MergeFunctions.cpp
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@ -367,6 +367,8 @@ private:
int cmpAPInt(const APInt &L, const APInt &R) const;
int cmpAPFloat(const APFloat &L, const APFloat &R) const;
int cmpStrings(StringRef L, StringRef R) const;
int cmpAttrs(const AttributeSet L, const AttributeSet R) const;
// The two functions undergoing comparison.
const Function *F1, *F2;
@ -432,6 +434,40 @@ int FunctionComparator::cmpAPFloat(const APFloat &L, const APFloat &R) const {
return cmpAPInt(L.bitcastToAPInt(), R.bitcastToAPInt());
}
int FunctionComparator::cmpStrings(StringRef L, StringRef R) const {
// Prevent heavy comparison, compare sizes first.
if (int Res = cmpNumbers(L.size(), R.size()))
return Res;
// Compare strings lexicographically only when it is necessary: only when
// strings are equal in size.
return L.compare(R);
}
int FunctionComparator::cmpAttrs(const AttributeSet L,
const AttributeSet R) const {
if (int Res = cmpNumbers(L.getNumSlots(), R.getNumSlots()))
return Res;
for (unsigned i = 0, e = L.getNumSlots(); i != e; ++i) {
AttributeSet::iterator LI = L.begin(i), LE = L.end(i), RI = R.begin(i),
RE = R.end(i);
for (; LI != LE && RI != RE; ++LI, ++RI) {
Attribute LA = *LI;
Attribute RA = *RI;
if (LA < RA)
return -1;
if (RA < LA)
return 1;
}
if (LI != LE)
return 1;
if (RI != RE)
return -1;
}
return 0;
}
/// Constants comparison:
/// 1. Check whether type of L constant could be losslessly bitcasted to R
/// type.