6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-06-16 12:24:03 +00:00
Code Issues Projects Releases Wiki Activity

Fix SCEV forgetMemoizedResults should search and destroy backedge exprs.

Browse Source 
Fixes PR15570: SEGV: SCEV back-edge info invalid after dead code removal.

Indvars creates a SCEV expression for the loop's back edge taken
count, then determines that the comparison is always true and
removes it.

When loop-unroll asks for the expression, it contains a NULL
SCEVUnknkown (as a CallbackVH).

forgetMemoizedResults should invalidate the loop back edges expression.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177986 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick
2013-03-26 03:14:53 +00:00
parent 7fc162f893
commit e74c2e86cb
3 changed files with 68 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

30
lib/Analysis/ScalarEvolution.cpp
View File

@ -4230,6 +4230,25 @@ ScalarEvolution::BackedgeTakenInfo::getMax(ScalarEvolution *SE) const {
return Max ? Max : SE->getCouldNotCompute();
}
bool ScalarEvolution::BackedgeTakenInfo::hasOperand(const SCEV *S,
ScalarEvolution *SE) const {
if (Max && Max != SE->getCouldNotCompute() && SE->hasOperand(Max, S))
return true;
if (!ExitNotTaken.ExitingBlock)
return false;
for (const ExitNotTakenInfo *ENT = &ExitNotTaken;
ENT != 0; ENT = ENT->getNextExit()) {
if (ENT->ExactNotTaken != SE->getCouldNotCompute()
&& SE->hasOperand(ENT->ExactNotTaken, S)) {
return true;
}
}
return false;
}
/// Allocate memory for BackedgeTakenInfo and copy the not-taken count of each
/// computable exit into a persistent ExitNotTakenInfo array.
ScalarEvolution::BackedgeTakenInfo::BackedgeTakenInfo(
@ -6940,6 +6959,17 @@ void ScalarEvolution::forgetMemoizedResults(const SCEV *S) {
BlockDispositions.erase(S);
UnsignedRanges.erase(S);
SignedRanges.erase(S);
for (DenseMap<const Loop*, BackedgeTakenInfo>::iterator I =
BackedgeTakenCounts.begin(), E = BackedgeTakenCounts.end(); I != E; ) {
BackedgeTakenInfo &BEInfo = I->second;
if (BEInfo.hasOperand(S, this)) {
BEInfo.clear();
BackedgeTakenCounts.erase(I++);
}
else
++I;
}
}
typedef DenseMap<const Loop *, std::string> VerifyMap;