maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Revert "[LIR] Start leveraging the fundamental guarantees of a loop..." 

This reverts commit r244879, as it broke the test-suite on
SingleSource/Regression/C/2004-03-15-IndirectGoto in AArch64.

llvm-svn: 244885
This commit is contained in:
Renato Golin 2015-08-13 11:25:38 +00:00
parent 4d57906b0e
commit 655348f0b2
1 changed files with 12 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
View File

@ -830,32 +830,29 @@ bool LoopIdiomRecognize::recognizePopcount() {
// non-compact loop. Therefore, recognizing popcount idiom only makes sense
// in a compact loop.
assert(CurLoop->isLoopSimplifyForm() &&
"Loop passes require simplified form!");
// Give up if the loop has multiple blocks.
if (CurLoop->getNumBlocks() != 1)
// Give up if the loop has multiple blocks or multiple backedges.
if (CurLoop->getNumBackEdges() != 1 || CurLoop->getNumBlocks() != 1)
return false;
// If the loop is too big, bail out.
BasicBlock &LoopBB = *CurLoop->getHeader();
if (LoopBB.size() >= 20)
BasicBlock *LoopBody = *(CurLoop->block_begin());
if (LoopBody->size() >= 20) {
// The loop is too big, bail out.
return false;
}
// It should have a preheader containing nothing but an unconditional branch.
BasicBlock &PH = *CurLoop->getLoopPreheader();
if (&PH.front() != PH.getTerminator())
BasicBlock *PH = CurLoop->getLoopPreheader();
if (!PH)
return false;
// FIXME: Technically, it shouldn't matter what instruction we use as
// a terminator, the only property needed is the definition of a preheader:
// a single loop predecessor whose only successor is the loop header.
auto *EntryBI = dyn_cast<BranchInst>(PH.getTerminator());
if (&PH->front() != PH->getTerminator())
return false;
auto *EntryBI = dyn_cast<BranchInst>(PH->getTerminator());
if (!EntryBI || EntryBI->isConditional())
return false;
// It should have a precondition block where the generated popcount instrinsic
// function can be inserted.
auto *PreCondBB = PH.getSinglePredecessor();
auto *PreCondBB = PH->getSinglePredecessor();
if (!PreCondBB)
return false;
auto *PreCondBI = dyn_cast<BranchInst>(PreCondBB->getTerminator());