SCEV: Use AssertingVH to catch dangling BasicBlock* when passes forget
to notify SCEV of a change. Add forgetLoop in a couple of those places. llvm-svn: 136797
This commit is contained in:
Andrew Trick
parent
e5ffe78c13
commit
bf69d03382
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@ -264,7 +264,7 @@ namespace llvm {
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/// ExitNotTakenInfo - Information about the number of times a particular
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/// loop exit may be reached before exiting the loop.
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struct ExitNotTakenInfo {
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BasicBlock *ExitingBlock;
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AssertingVH<BasicBlock> ExitingBlock;
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const SCEV *ExactNotTaken;
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PointerIntPair<ExitNotTakenInfo*, 1> NextExit;
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@ -325,6 +325,14 @@ ReprocessLoop:
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DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block "
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<< ExitingBlock->getName() << "\n");
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// If any reachable control flow within this loop has changed, notify
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// ScalarEvolution. Currently assume the parent loop doesn't change
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// (spliting edges doesn't count). If blocks, CFG edges, or other values
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// in the parent loop change, then we need call to forgetLoop() for the
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// parent instead.
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if (SE)
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SE->forgetLoop(L);
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assert(pred_begin(ExitingBlock) == pred_end(ExitingBlock));
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Changed = true;
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LI->removeBlock(ExitingBlock);
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@ -58,7 +58,8 @@ static inline void RemapInstruction(Instruction *I,
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/// only has one predecessor, and that predecessor only has one successor.
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/// The LoopInfo Analysis that is passed will be kept consistent.
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/// Returns the new combined block.
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static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
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static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI,
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LPPassManager *LPM) {
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// Merge basic blocks into their predecessor if there is only one distinct
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// pred, and if there is only one distinct successor of the predecessor, and
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// if there are no PHI nodes.
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@ -90,6 +91,12 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
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std::string OldName = BB->getName();
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// Erase basic block from the function...
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// ScalarEvolution holds references to loop exit blocks.
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if (ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>()) {
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if (Loop *L = LI->getLoopFor(BB))
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SE->forgetLoop(L);
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}
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LI->removeBlock(BB);
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BB->eraseFromParent();
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@ -364,7 +371,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
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BranchInst *Term = cast<BranchInst>(Latches[i]->getTerminator());
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if (Term->isUnconditional()) {
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BasicBlock *Dest = Term->getSuccessor(0);
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if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI))
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if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI, LPM))
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std::replace(Latches.begin(), Latches.end(), Dest, Fold);
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}
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}
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@ -48,3 +48,91 @@ return: ; preds = %for.body18, %for.bo
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}
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declare void @foo() nounwind
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; Notify SCEV when removing an ExitingBlock.
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; CHECK: @mergeExit
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; CHECK: while.cond191:
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; CHECK: br i1 %or.cond, label %while.body197
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; CHECK-NOT: land.rhs:
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; CHECK: ret
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define void @mergeExit(i32 %MapAttrCount) nounwind uwtable ssp {
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entry:
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br i1 undef, label %if.then124, label %if.end126
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if.then124: ; preds = %entry
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unreachable
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if.end126: ; preds = %entry
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br i1 undef, label %while.body.lr.ph, label %if.end591
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while.body.lr.ph: ; preds = %if.end126
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br i1 undef, label %if.end140, label %if.then137
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if.then137: ; preds = %while.body.lr.ph
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unreachable
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if.end140: ; preds = %while.body.lr.ph
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br i1 undef, label %while.cond191.outer, label %if.then148
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if.then148: ; preds = %if.end140
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unreachable
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while.cond191.outer: ; preds = %if.then205, %if.end140
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br label %while.cond191
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while.cond191: ; preds = %while.body197, %while.cond191.outer
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%CppIndex.0 = phi i32 [ %inc, %while.body197 ], [ undef, %while.cond191.outer ]
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br i1 undef, label %land.rhs, label %if.then216
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land.rhs: ; preds = %while.cond191
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%inc = add i32 %CppIndex.0, 1
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%cmp196 = icmp ult i32 %inc, %MapAttrCount
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br i1 %cmp196, label %while.body197, label %if.then216
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while.body197: ; preds = %land.rhs
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br i1 undef, label %if.then205, label %while.cond191
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if.then205: ; preds = %while.body197
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br label %while.cond191.outer
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if.then216: ; preds = %land.rhs, %while.cond191
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br i1 undef, label %if.else, label %if.then221
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if.then221: ; preds = %if.then216
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unreachable
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if.else: ; preds = %if.then216
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br i1 undef, label %if.then266, label %if.end340
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if.then266: ; preds = %if.else
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switch i32 undef, label %if.else329 [
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i32 17, label %if.then285
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i32 19, label %if.then285
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i32 18, label %if.then285
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i32 15, label %if.then285
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]
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if.then285: ; preds = %if.then266, %if.then266, %if.then266, %if.then266
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br i1 undef, label %if.then317, label %if.else324
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if.then317: ; preds = %if.then285
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br label %if.end340
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if.else324: ; preds = %if.then285
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unreachable
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if.else329: ; preds = %if.then266
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unreachable
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if.end340: ; preds = %if.then317, %if.else
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unreachable
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if.end591: ; preds = %if.end126
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br i1 undef, label %cond.end, label %cond.false
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cond.false: ; preds = %if.end591
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unreachable
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cond.end: ; preds = %if.end591
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ret void
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}
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