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Fix an issue where LSR would miss rewriting a use of an IV expression by a PHI node that is not the original PHI.

This fixes up a dot-product loop in galgel, speeding it up from 18.47s to
16.13s.

llvm-svn: 23327
This commit is contained in:
Chris Lattner 2005-09-13 02:09:55 +00:00
parent 5c8de93882
commit 26aef8992f

View File

@ -333,14 +333,14 @@ bool LoopStrengthReduce::AddUsersIfInteresting(Instruction *I, Loop *L,
Instruction *User = cast<Instruction>(*UI);
// Do not infinitely recurse on PHI nodes.
if (isa<PHINode>(User) && User->getParent() == L->getHeader())
if (isa<PHINode>(User) && Processed.count(User))
continue;
// If this is an instruction defined in a nested loop, or outside this loop,
// don't recurse into it.
bool AddUserToIVUsers = false;
if (LI->getLoopFor(User->getParent()) != L) {
DEBUG(std::cerr << "FOUND USER in nested loop: " << *User
DEBUG(std::cerr << "FOUND USER in other loop: " << *User
<< " OF SCEV: " << *ISE << "\n");
AddUserToIVUsers = true;
} else if (!AddUsersIfInteresting(User, L, Processed)) {
@ -459,9 +459,13 @@ void BasedUser::RewriteInstructionToUseNewBase(const SCEVHandle &NewBase,
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) == OperandValToReplace) {
// If this is a critical edge, split the edge so that we do not insert the
// code on all predecessor/successor paths.
// code on all predecessor/successor paths. We do this unless this is the
// canonical backedge for this loop, as this can make some inserted code
// be in an illegal position.
if (e != 1 &&
PN->getIncomingBlock(i)->getTerminator()->getNumSuccessors() > 1) {
PN->getIncomingBlock(i)->getTerminator()->getNumSuccessors() > 1 &&
(PN->getParent() != L->getHeader() ||
!L->contains(PN->getIncomingBlock(i)))) {
// First step, split the critical edge.
SplitCriticalEdge(PN->getIncomingBlock(i), PN->getParent(), P);