diff options
| -rw-r--r-- | include/llvm/Analysis/ScalarEvolution.h | 2 | ||||
| -rw-r--r-- | lib/Transforms/Utils/LoopSimplify.cpp | 8 | ||||
| -rw-r--r-- | lib/Transforms/Utils/LoopUnroll.cpp | 11 | ||||
| -rw-r--r-- | test/Transforms/LoopSimplify/preserve-scev.ll | 88 |
4 files changed, 106 insertions, 3 deletions
diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h index fa9e402abd..c621bec86a 100644 --- a/include/llvm/Analysis/ScalarEvolution.h +++ b/include/llvm/Analysis/ScalarEvolution.h @@ -264,7 +264,7 @@ namespace llvm { /// ExitNotTakenInfo - Information about the number of times a particular /// loop exit may be reached before exiting the loop. struct ExitNotTakenInfo { - BasicBlock *ExitingBlock; + AssertingVH<BasicBlock> ExitingBlock; const SCEV *ExactNotTaken; PointerIntPair<ExitNotTakenInfo*, 1> NextExit; diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp index 9af338ec7f..9b16c7cbe1 100644 --- a/lib/Transforms/Utils/LoopSimplify.cpp +++ b/lib/Transforms/Utils/LoopSimplify.cpp @@ -325,6 +325,14 @@ ReprocessLoop: DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block " << ExitingBlock->getName() << "\n"); + // If any reachable control flow within this loop has changed, notify + // ScalarEvolution. Currently assume the parent loop doesn't change + // (spliting edges doesn't count). If blocks, CFG edges, or other values + // in the parent loop change, then we need call to forgetLoop() for the + // parent instead. + if (SE) + SE->forgetLoop(L); + assert(pred_begin(ExitingBlock) == pred_end(ExitingBlock)); Changed = true; LI->removeBlock(ExitingBlock); diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp index dddf43ea57..5a40a09580 100644 --- a/lib/Transforms/Utils/LoopUnroll.cpp +++ b/lib/Transforms/Utils/LoopUnroll.cpp @@ -58,7 +58,8 @@ static inline void RemapInstruction(Instruction *I, /// only has one predecessor, and that predecessor only has one successor. /// The LoopInfo Analysis that is passed will be kept consistent. /// Returns the new combined block. -static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) { +static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI, + LPPassManager *LPM) { // Merge basic blocks into their predecessor if there is only one distinct // pred, and if there is only one distinct successor of the predecessor, and // if there are no PHI nodes. @@ -90,6 +91,12 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) { std::string OldName = BB->getName(); // Erase basic block from the function... + + // ScalarEvolution holds references to loop exit blocks. + if (ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>()) { + if (Loop *L = LI->getLoopFor(BB)) + SE->forgetLoop(L); + } LI->removeBlock(BB); BB->eraseFromParent(); @@ -364,7 +371,7 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, BranchInst *Term = cast<BranchInst>(Latches[i]->getTerminator()); if (Term->isUnconditional()) { BasicBlock *Dest = Term->getSuccessor(0); - if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI)) + if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI, LPM)) std::replace(Latches.begin(), Latches.end(), Dest, Fold); } } diff --git a/test/Transforms/LoopSimplify/preserve-scev.ll b/test/Transforms/LoopSimplify/preserve-scev.ll index 017a0d2108..23ac7f257a 100644 --- a/test/Transforms/LoopSimplify/preserve-scev.ll +++ b/test/Transforms/LoopSimplify/preserve-scev.ll @@ -48,3 +48,91 @@ return: ; preds = %for.body18, %for.bo } declare void @foo() nounwind + +; Notify SCEV when removing an ExitingBlock. +; CHECK: @mergeExit +; CHECK: while.cond191: +; CHECK: br i1 %or.cond, label %while.body197 +; CHECK-NOT: land.rhs: +; CHECK: ret +define void @mergeExit(i32 %MapAttrCount) nounwind uwtable ssp { +entry: + br i1 undef, label %if.then124, label %if.end126 + +if.then124: ; preds = %entry + unreachable + +if.end126: ; preds = %entry + br i1 undef, label %while.body.lr.ph, label %if.end591 + +while.body.lr.ph: ; preds = %if.end126 + br i1 undef, label %if.end140, label %if.then137 + +if.then137: ; preds = %while.body.lr.ph + unreachable + +if.end140: ; preds = %while.body.lr.ph + br i1 undef, label %while.cond191.outer, label %if.then148 + +if.then148: ; preds = %if.end140 + unreachable + +while.cond191.outer: ; preds = %if.then205, %if.end140 + br label %while.cond191 + +while.cond191: ; preds = %while.body197, %while.cond191.outer + %CppIndex.0 = phi i32 [ %inc, %while.body197 ], [ undef, %while.cond191.outer ] + br i1 undef, label %land.rhs, label %if.then216 + +land.rhs: ; preds = %while.cond191 + %inc = add i32 %CppIndex.0, 1 + %cmp196 = icmp ult i32 %inc, %MapAttrCount + br i1 %cmp196, label %while.body197, label %if.then216 + +while.body197: ; preds = %land.rhs + br i1 undef, label %if.then205, label %while.cond191 + +if.then205: ; preds = %while.body197 + br label %while.cond191.outer + +if.then216: ; preds = %land.rhs, %while.cond191 + br i1 undef, label %if.else, label %if.then221 + +if.then221: ; preds = %if.then216 + unreachable + +if.else: ; preds = %if.then216 + br i1 undef, label %if.then266, label %if.end340 + +if.then266: ; preds = %if.else + switch i32 undef, label %if.else329 [ + i32 17, label %if.then285 + i32 19, label %if.then285 + i32 18, label %if.then285 + i32 15, label %if.then285 + ] + +if.then285: ; preds = %if.then266, %if.then266, %if.then266, %if.then266 + br i1 undef, label %if.then317, label %if.else324 + +if.then317: ; preds = %if.then285 + br label %if.end340 + +if.else324: ; preds = %if.then285 + unreachable + +if.else329: ; preds = %if.then266 + unreachable + +if.end340: ; preds = %if.then317, %if.else + unreachable + +if.end591: ; preds = %if.end126 + br i1 undef, label %cond.end, label %cond.false + +cond.false: ; preds = %if.end591 + unreachable + +cond.end: ; preds = %if.end591 + ret void +} |