Merging r324916:

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r324916 | junbuml | 2018-02-12 18:56:55 +0100 (Mon, 12 Feb 2018) | 7 lines

[LICM] update BlockColors after splitting predecessors

Update BlockColors after splitting predecessors. Do not allow splitting
EHPad for sinking when the BlockColors is not empty, so we can
simply assign predecessor's color to the new block.

Fixes PR36184
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@325507 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 4ea935793b802bfd65303aa5abf9ffe96273e839..946474fef06252964f166f736e2914a91a98080f 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -97,7 +97,7 @@ static bool hoist(Instruction &I, const DominatorTree *DT, const Loop *CurLoop,
                   const LoopSafetyInfo *SafetyInfo,
                   OptimizationRemarkEmitter *ORE);
 static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
-                 const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo,
+                 const Loop *CurLoop, LoopSafetyInfo *SafetyInfo,
                  OptimizationRemarkEmitter *ORE, bool FreeInLoop);
 static bool isSafeToExecuteUnconditionally(Instruction &Inst,
                                            const DominatorTree *DT,
@@ -855,10 +855,16 @@ static Instruction *sinkThroughTriviallyReplacablePHI(
   return New;
 }
 
-static bool canSplitPredecessors(PHINode *PN) {
+static bool canSplitPredecessors(PHINode *PN, LoopSafetyInfo *SafetyInfo) {
   BasicBlock *BB = PN->getParent();
   if (!BB->canSplitPredecessors())
     return false;
+  // It's not impossible to split EHPad blocks, but if BlockColors already exist
+  // it require updating BlockColors for all offspring blocks accordingly. By
+  // skipping such corner case, we can make updating BlockColors after splitting
+  // predecessor fairly simple.
+  if (!SafetyInfo->BlockColors.empty() && BB->getFirstNonPHI()->isEHPad())
+    return false;
   for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
     BasicBlock *BBPred = *PI;
     if (isa<IndirectBrInst>(BBPred->getTerminator()))
@@ -868,7 +874,8 @@ static bool canSplitPredecessors(PHINode *PN) {
 }
 
 static void splitPredecessorsOfLoopExit(PHINode *PN, DominatorTree *DT,
-                                        LoopInfo *LI, const Loop *CurLoop) {
+                                        LoopInfo *LI, const Loop *CurLoop,
+                                        LoopSafetyInfo *SafetyInfo) {
 #ifndef NDEBUG
   SmallVector<BasicBlock *, 32> ExitBlocks;
   CurLoop->getUniqueExitBlocks(ExitBlocks);
@@ -910,13 +917,21 @@ static void splitPredecessorsOfLoopExit(PHINode *PN, DominatorTree *DT,
   // LE:
   //   %p = phi [%p1, %LE.split], [%p2, %LE.split2]
   //
+  auto &BlockColors = SafetyInfo->BlockColors;
   SmallSetVector<BasicBlock *, 8> PredBBs(pred_begin(ExitBB), pred_end(ExitBB));
   while (!PredBBs.empty()) {
     BasicBlock *PredBB = *PredBBs.begin();
     assert(CurLoop->contains(PredBB) &&
            "Expect all predecessors are in the loop");
-    if (PN->getBasicBlockIndex(PredBB) >= 0)
-      SplitBlockPredecessors(ExitBB, PredBB, ".split.loop.exit", DT, LI, true);
+    if (PN->getBasicBlockIndex(PredBB) >= 0) {
+      BasicBlock *NewPred = SplitBlockPredecessors(
+          ExitBB, PredBB, ".split.loop.exit", DT, LI, true);
+      // Since we do not allow splitting EH-block with BlockColors in
+      // canSplitPredecessors(), we can simply assign predecessor's color to
+      // the new block.
+      if (!BlockColors.empty())
+        BlockColors[NewPred] = BlockColors[PredBB];
+    }
     PredBBs.remove(PredBB);
   }
 }
@@ -927,7 +942,7 @@ static void splitPredecessorsOfLoopExit(PHINode *PN, DominatorTree *DT,
 /// position, and may either delete it or move it to outside of the loop.
 ///
 static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
-                 const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo,
+                 const Loop *CurLoop, LoopSafetyInfo *SafetyInfo,
                  OptimizationRemarkEmitter *ORE, bool FreeInLoop) {
   DEBUG(dbgs() << "LICM sinking instruction: " << I << "\n");
   ORE->emit([&]() {
@@ -975,12 +990,12 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
     if (isTriviallyReplacablePHI(*PN, I))
       continue;
 
-    if (!canSplitPredecessors(PN))
+    if (!canSplitPredecessors(PN, SafetyInfo))
       return Changed;
 
     // Split predecessors of the PHI so that we can make users trivially
     // replacable.
-    splitPredecessorsOfLoopExit(PN, DT, LI, CurLoop);
+    splitPredecessorsOfLoopExit(PN, DT, LI, CurLoop, SafetyInfo);
 
     // Should rebuild the iterators, as they may be invalidated by
     // splitPredecessorsOfLoopExit().

diff --git a/test/Transforms/LICM/sinking.ll b/test/Transforms/LICM/sinking.ll
index b28eea0bc2aa6635580e92980f0138a3cbb72ce2..6d747877c58e73d896375209d6d6a33373cadf01 100644 (file)
--- a/test/Transforms/LICM/sinking.ll
+++ b/test/Transforms/LICM/sinking.ll
@@ -670,6 +670,67 @@ try.cont:
   ret void
 }
 
+; The sinkable call should be sunk into an exit block split. After splitting
+; the exit block, BlockColor for new blocks should be added properly so
+; that we should be able to access valid ColorVector.
+;
+; CHECK-LABEL:@test21_pr36184
+; CHECK-LABEL: Loop
+; CHECK-NOT: %sinkableCall
+; CHECK-LABEL:Out.split.loop.exit
+; CHECK: %sinkableCall
+define i32 @test21_pr36184(i8* %P) personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+  br label %loop.ph
+
+loop.ph:
+  br label %Loop
+
+Loop:
+  %sinkableCall = call i32 @strlen( i8* %P ) readonly
+  br i1 undef, label %ContLoop, label %Out
+
+ContLoop:
+  br i1 undef, label %Loop, label %Out
+
+Out:
+  %idx = phi i32 [ %sinkableCall, %Loop ], [0, %ContLoop ]
+  ret i32 %idx
+}
+
+; We do not support splitting a landingpad block if BlockColors is not empty.
+; CHECK-LABEL: @test22
+; CHECK-LABEL: while.body2
+; CHECK-LABEL: %mul
+; CHECK-NOT: lpadBB.split{{.*}}
+define void @test22(i1 %b, i32 %v1, i32 %v2) personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+  br label %while.cond
+while.cond:
+  br i1 %b, label %try.cont, label %while.body
+
+while.body:
+  invoke void @may_throw()
+          to label %while.body2 unwind label %lpadBB
+
+while.body2:
+  %v = call i32 @getv()
+  %mul = mul i32 %v, %v2
+  invoke void @may_throw2()
+          to label %while.cond unwind label %lpadBB
+lpadBB:
+  %.lcssa1 = phi i32 [ 0, %while.body ], [ %mul, %while.body2 ]
+  landingpad { i8*, i32 }
+               catch i8* null
+  br label %lpadBBSucc1
+
+lpadBBSucc1:
+  ret void
+
+try.cont:
+  ret void
+}
+
 declare void @may_throw()
 declare void @may_throw2()
 declare i32 @__CxxFrameHandler3(...)