aboutsummaryrefslogtreecommitdiffstats
path: root/tools/llvm-diff
diff options
context:
space:
mode:
authorJohn McCall <rjmccall@apple.com>2010-07-29 08:53:59 +0000
committerJohn McCall <rjmccall@apple.com>2010-07-29 08:53:59 +0000
commitdfb44ac690b9404469a485e252f4ac026bcdefa1 (patch)
treeb85f8262ebfbef0a2a5c938a61a2b76e369b0789 /tools/llvm-diff
parent62dc1f3d827df8b0e2f88ae9e649893d0dbe8830 (diff)
downloadexternal_llvm-dfb44ac690b9404469a485e252f4ac026bcdefa1.zip
external_llvm-dfb44ac690b9404469a485e252f4ac026bcdefa1.tar.gz
external_llvm-dfb44ac690b9404469a485e252f4ac026bcdefa1.tar.bz2
Somehow I was getting reasonable results for the test cases I was interested
in despite not ever incrementing any path costs, so that the only nonzero costs arose from the all-left path in the first column. Anyway. Perform the diff starting from the beginning of the block to avoid capturing (say) loads of allocas. Vastly improves diff results on code that hasn't been mem2reg'ed. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109741 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'tools/llvm-diff')
-rw-r--r--tools/llvm-diff/DifferenceEngine.cpp52
1 files changed, 38 insertions, 14 deletions
diff --git a/tools/llvm-diff/DifferenceEngine.cpp b/tools/llvm-diff/DifferenceEngine.cpp
index 0f10bc7..769dc0a 100644
--- a/tools/llvm-diff/DifferenceEngine.cpp
+++ b/tools/llvm-diff/DifferenceEngine.cpp
@@ -124,7 +124,7 @@ class FunctionDifferenceEngine {
/// The current mapping from old blocks to new blocks.
DenseMap<BasicBlock*, BasicBlock*> Blocks;
- DenseSet<std::pair<Value*, Value*> > TentativeValuePairs;
+ DenseSet<std::pair<Value*, Value*> > TentativeValues;
unsigned getUnprocPredCount(BasicBlock *Block) const {
unsigned Count = 0;
@@ -186,22 +186,32 @@ class FunctionDifferenceEngine {
BasicBlock::iterator LI = L->begin(), LE = L->end();
BasicBlock::iterator RI = R->begin(), RE = R->end();
+ llvm::SmallVector<std::pair<Instruction*,Instruction*>, 20> TentativePairs;
+
do {
assert(LI != LE && RI != RE);
Instruction *LeftI = &*LI, *RightI = &*RI;
// If the instructions differ, start the more sophisticated diff
- // algorithm here.
- if (diff(LeftI, RightI, false, true))
- return runBlockDiff(LI, RI);
+ // algorithm at the start of the block.
+ if (diff(LeftI, RightI, false, true)) {
+ TentativeValues.clear();
+ return runBlockDiff(L->begin(), R->begin());
+ }
- // Otherwise, unify them.
+ // Otherwise, tentatively unify them.
if (!LeftI->use_empty())
- Values[LeftI] = RightI;
+ TentativeValues.insert(std::make_pair(LeftI, RightI));
++LI, ++RI;
} while (LI != LE); // This is sufficient: we can't get equality of
// terminators if there are residual instructions.
+
+ // Make all the tentative pairs solid.
+ for (llvm::DenseSet<std::pair<Value*,Value*> >::iterator
+ I = TentativeValues.begin(), E = TentativeValues.end(); I != E; ++I)
+ Values[I->first] = I->second;
+ TentativeValues.clear();
}
bool matchForBlockDiff(Instruction *L, Instruction *R);
@@ -417,7 +427,7 @@ class FunctionDifferenceEngine {
return equivalentAsOperands(cast<Constant>(L), cast<Constant>(R));
if (isa<Instruction>(L))
- return Values[L] == R || TentativeValuePairs.count(std::make_pair(L, R));
+ return Values[L] == R || TentativeValues.count(std::make_pair(L, R));
if (isa<Argument>(L))
return Values[L] == R;
@@ -477,11 +487,15 @@ void FunctionDifferenceEngine::runBlockDiff(BasicBlock::iterator LStart,
DiffEntry *Cur = Paths1.data();
DiffEntry *Next = Paths2.data();
- assert(TentativeValuePairs.empty());
+ const unsigned LeftCost = 2;
+ const unsigned RightCost = 2;
+ const unsigned MatchCost = 0;
+
+ assert(TentativeValues.empty());
// Initialize the first column.
for (unsigned I = 0; I != NL+1; ++I) {
- Cur[I].Cost = I;
+ Cur[I].Cost = I * LeftCost;
for (unsigned J = 0; J != I; ++J)
Cur[I].Path.push_back(DifferenceEngine::DC_left);
}
@@ -489,19 +503,23 @@ void FunctionDifferenceEngine::runBlockDiff(BasicBlock::iterator LStart,
for (BasicBlock::iterator RI = RStart; RI != RE; ++RI) {
// Initialize the first row.
Next[0] = Cur[0];
+ Next[0].Cost += RightCost;
Next[0].Path.push_back(DifferenceEngine::DC_right);
unsigned Index = 1;
for (BasicBlock::iterator LI = LStart; LI != LE; ++LI, ++Index) {
if (matchForBlockDiff(&*LI, &*RI)) {
Next[Index] = Cur[Index-1];
+ Next[Index].Cost += MatchCost;
Next[Index].Path.push_back(DifferenceEngine::DC_match);
- TentativeValuePairs.insert(std::make_pair(&*LI, &*RI));
+ TentativeValues.insert(std::make_pair(&*LI, &*RI));
} else if (Next[Index-1].Cost <= Cur[Index].Cost) {
Next[Index] = Next[Index-1];
+ Next[Index].Cost += LeftCost;
Next[Index].Path.push_back(DifferenceEngine::DC_left);
} else {
Next[Index] = Cur[Index];
+ Next[Index].Cost += RightCost;
Next[Index].Path.push_back(DifferenceEngine::DC_right);
}
}
@@ -518,15 +536,21 @@ void FunctionDifferenceEngine::runBlockDiff(BasicBlock::iterator LStart,
while (Path.back() == DifferenceEngine::DC_match)
Path.pop_back();
- for (SmallVectorImpl<char>::iterator
- PI = Path.begin(), PE = Path.end(); PI != PE; ++PI) {
+ // Skip leading matches.
+ SmallVectorImpl<char>::iterator
+ PI = Path.begin(), PE = Path.end();
+ while (PI != PE && *PI == DifferenceEngine::DC_match)
+ ++PI, ++LI, ++RI;
+
+ for (; PI != PE; ++PI) {
switch (static_cast<DifferenceEngine::DiffChange>(*PI)) {
case DifferenceEngine::DC_match:
assert(LI != LE && RI != RE);
{
Instruction *L = &*LI, *R = &*RI;
DifferenceEngine::Context C(Engine, L, R);
- diff(L, R, false, true);
+ diff(L, R, false, true); // unify successors
+ Values[L] = R; // make non-tentative
Diff.addMatch(L, R);
}
++LI; ++RI;
@@ -546,7 +570,7 @@ void FunctionDifferenceEngine::runBlockDiff(BasicBlock::iterator LStart,
}
}
- TentativeValuePairs.clear();
+ TentativeValues.clear();
}
}