6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-26 20:26:07 +00:00
Code Issues Projects Releases Wiki Activity

Fix a bug in vectorization of if-converted reduction variables. If the

Browse Source 
reduction variable is not used outside the loop then we ran into an
endless loop. This change checks if we found the original PHI.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169324 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2012-12-04 22:40:22 +00:00
parent f7999fe1cb
commit e570dee4b0
2 changed files with 61 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@@ -1985,20 +1985,20 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
// Also, we can't have multiple block-local users.
Instruction *Iter = Phi;
while (true) {
// Any reduction instr must be of one of the allowed kinds.
if (!isReductionInstr(Iter, Kind))
return false;
// Did we found a user inside this block ?
bool FoundInBlockUser = false;
// Did we reach the initial PHI node ?
bool FoundStartPHI = false;
// If the instruction has no users then this is a broken
// chain and can't be a reduction variable.
if (Iter->use_empty())
return false;
// Any reduction instr must be of one of the allowed kinds.
if (!isReductionInstr(Iter, Kind))
return false;
// Did we find a user inside this block ?
bool FoundInBlockUser = false;
// Did we reach the initial PHI node ?
bool FoundStartPHI = false;
// For each of the *users* of iter.
for (Value::use_iterator it = Iter->use_begin(), e = Iter->use_end();
it != e; ++it) {
@@ -2009,21 +2009,22 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
continue;
}
// We allow in-loop PHINodes which are not the original reduction PHI
// node. If this PHI is the only user of Iter (happens in IF w/ no ELSE
// structure) then don't skip this PHI.
if (isa<PHINode>(U) && U->getParent() != TheLoop->getHeader() &&
TheLoop->contains(U->getParent()) && Iter->getNumUses() > 1)
continue;
// Check if we found the exit user.
BasicBlock *Parent = U->getParent();
if (!TheLoop->contains(Parent)) {
// We must have a single exit instruction.
// Exit if you find multiple outside users.
if (ExitInstruction != 0)
return false;
ExitInstruction = Iter;
}
// We allow in-loop PHINodes which are not the original reduction PHI
// node. If this PHI is the only user of Iter (happens in IF w/ no ELSE
// structure) then don't skip this PHI.
if (isa<PHINode>(U) && U->getParent() != TheLoop->getHeader() &&
TheLoop->contains(U) && Iter->getNumUses() > 1)
continue;
// We can't have multiple inside users.
if (FoundInBlockUser)
return false;
@@ -2043,6 +2044,11 @@ bool LoopVectorizationLegality::AddReductionVar(PHINode *Phi,
Reductions[Phi] = RD;
return true;
}
// If we've reached the start PHI but did not find an outside user then
// this is dead code. Abort.
if (FoundStartPHI)
return false;
}
}