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StructurizeCFG: Use LoopInfo analysis for better loop detection

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We were assuming that each back-edge in a region represented a unique
loop, which is not always the case.  We need to use LoopInfo to
correctly determine which back-edges are loops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223199 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tom Stellard
2014-12-03 04:28:32 +00:00
parent 2212800542
commit 857550322c
2 changed files with 47 additions and 1 deletions
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7
lib/Transforms/Scalar/StructurizeCFG.cpp
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@ -10,6 +10,7 @@
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/RegionInfo.h"
#include "llvm/Analysis/RegionIterator.h"
#include "llvm/Analysis/RegionPass.h"
@ -166,6 +167,7 @@ class StructurizeCFG : public RegionPass {
Region *ParentRegion;
DominatorTree *DT;
LoopInfo *LI;
RNVector Order;
BBSet Visited;
@ -247,6 +249,7 @@ public:
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequiredID(LowerSwitchID);
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfo>();
AU.addPreserved<DominatorTreeWrapperPass>();
RegionPass::getAnalysisUsage(AU);
}
@ -301,8 +304,9 @@ void StructurizeCFG::analyzeLoops(RegionNode *N) {
for (unsigned i = 0, e = Term->getNumSuccessors(); i != e; ++i) {
BasicBlock *Succ = Term->getSuccessor(i);
if (Visited.count(Succ))
if (Visited.count(Succ) && LI->isLoopHeader(Succ) ) {
Loops[Succ] = BB;
}
}
}
}
@ -862,6 +866,7 @@ bool StructurizeCFG::runOnRegion(Region *R, RGPassManager &RGM) {
ParentRegion = R;
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
LI = &getAnalysis<LoopInfo>();
orderNodes();
collectInfos();