[PATCH] D109646: [LNICM] Fix the crashing problem

[toshiki maekawa via Phabricator via llvm-commits]

uint256_t created this revision.
uint256_t added a reviewer: uabelho.
Herald added subscribers: asbirlea, hiraditya.
uint256_t requested review of this revision.
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This patch fixes the problem reported in https://reviews.llvm.org/D107219.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109646

Files:
  llvm/lib/Transforms/Scalar/LICM.cpp
  llvm/test/Transforms/LICM/lnicm-crash.ll


Index: llvm/test/Transforms/LICM/lnicm-crash.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LICM/lnicm-crash.ll
@@ -0,0 +1,23 @@
+; RUN: opt -passes='loop-mssa(licm)' -S %s
+; RUN: opt -passes='loop-mssa(lnicm)' -S %s
+
+define void @main() {
+entry:
+  br label %for.body1143
+
+land.rhs1135:                                     ; preds = %for.body1143
+  %v_299.017 = phi i40 [ %0, %for.body1143 ]
+  br i1 true, label %land.rhs1135.for.cond.cleanup1952_crit_edge, label %for.body1143
+
+for.body1143:                                     ; preds = %land.rhs1135, %entry
+  %0 = select i1 undef, i40 undef, i40 253841517325
+  br i1 true, label %for.body1143.for.cond.cleanup1952_crit_edge, label %land.rhs1135
+
+for.body1143.for.cond.cleanup1952_crit_edge:      ; preds = %for.body1143
+  %split = phi i40 [ %0, %for.body1143 ]
+  unreachable
+
+land.rhs1135.for.cond.cleanup1952_crit_edge:      ; preds = %land.rhs1135
+  %split1 = phi i40 [ %v_299.017, %land.rhs1135 ]
+  unreachable
+}
Index: llvm/lib/Transforms/Scalar/LICM.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LICM.cpp
+++ llvm/lib/Transforms/Scalar/LICM.cpp
@@ -143,9 +143,9 @@
 
 static bool inSubLoop(BasicBlock *BB, Loop *CurLoop, LoopInfo *LI);
 static bool isNotUsedOrFreeInLoop(const Instruction &I, const Loop *CurLoop,
+                                  const Loop *OutermostLoop,
                                   const LoopSafetyInfo *SafetyInfo,
-                                  TargetTransformInfo *TTI, bool &FreeInLoop,
-                                  bool LoopNestMode);
+                                  TargetTransformInfo *TTI, bool &FreeInLoop);
 static void hoist(Instruction &I, const DominatorTree *DT, const Loop *CurLoop,
                   BasicBlock *Dest, ICFLoopSafetyInfo *SafetyInfo,
                   MemorySSAUpdater *MSSAU, ScalarEvolution *SE,
@@ -551,12 +551,11 @@
       // operands of the instruction are loop invariant.
       //
       bool FreeInLoop = false;
-      bool LoopNestMode = OutermostLoop != nullptr;
       if (!I.mayHaveSideEffects() &&
-          isNotUsedOrFreeInLoop(I, LoopNestMode ? OutermostLoop : CurLoop,
-                                SafetyInfo, TTI, FreeInLoop, LoopNestMode) &&
-          canSinkOrHoistInst(I, AA, DT, CurLoop, /*CurAST*/nullptr, MSSAU, true,
-                             &Flags, ORE)) {
+          isNotUsedOrFreeInLoop(I, CurLoop, OutermostLoop, SafetyInfo, TTI,
+                                FreeInLoop) &&
+          canSinkOrHoistInst(I, AA, DT, CurLoop, /*CurAST*/ nullptr, MSSAU,
+                             true, &Flags, ORE)) {
         if (sink(I, LI, DT, BFI, CurLoop, SafetyInfo, MSSAU, ORE)) {
           if (!FreeInLoop) {
             ++II;
@@ -1410,11 +1409,12 @@
 /// We also return true if the instruction could be folded away in lowering.
 /// (e.g.,  a GEP can be folded into a load as an addressing mode in the loop).
 static bool isNotUsedOrFreeInLoop(const Instruction &I, const Loop *CurLoop,
+                                  const Loop *OutermostLoop,
                                   const LoopSafetyInfo *SafetyInfo,
-                                  TargetTransformInfo *TTI, bool &FreeInLoop,
-                                  bool LoopNestMode) {
+                                  TargetTransformInfo *TTI, bool &FreeInLoop) {
   const auto &BlockColors = SafetyInfo->getBlockColors();
-  bool IsFree = isFreeInLoop(I, CurLoop, TTI);
+  const bool LoopNestMode = OutermostLoop != nullptr;
+  bool IsFree = isFreeInLoop(I, LoopNestMode ? OutermostLoop : CurLoop, TTI);
   for (const User *U : I.users()) {
     const Instruction *UI = cast<Instruction>(U);
     if (const PHINode *PN = dyn_cast<PHINode>(UI)) {
@@ -1433,14 +1433,16 @@
       if (LoopNestMode) {
         while (isa<PHINode>(UI) && UI->hasOneUser() &&
                UI->getNumOperands() == 1) {
-          if (!CurLoop->contains(UI))
+          if (CurLoop == OutermostLoop && CurLoop->contains(UI))
+            break;
+          if (!OutermostLoop->contains(UI))
             break;
           UI = cast<Instruction>(UI->user_back());
         }
       }
     }
 
-    if (CurLoop->contains(UI)) {
+    if ((LoopNestMode ? OutermostLoop : CurLoop)->contains(UI)) {
       if (IsFree) {
         FreeInLoop = true;
         continue;


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