[llvm-commits] [llvm] r144454 - in /llvm/trunk: lib/Analysis/ScalarEvolution.cpp test/Transforms/LoopUnroll/pr11361.ll

[Nick Lewycky]

Author: nicholas
Date: Fri Nov 11 21:09:12 2011
New Revision: 144454

URL: http://llvm.org/viewvc/llvm-project?rev=144454&view=rev
Log:
Don't try to loop on iterators that are potentially invalidated inside the loop. Fixes PR11361!

Added:
    llvm/trunk/test/Transforms/LoopUnroll/pr11361.ll
Modified:
    llvm/trunk/lib/Analysis/ScalarEvolution.cpp

Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=144454&r1=144453&r2=144454&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Fri Nov 11 21:09:12 2011
@@ -4853,10 +4853,18 @@
     // Also evaluate the other PHI nodes.  However, we don't get to stop if we
     // cease to be able to evaluate one of them or if they stop evolving,
     // because that doesn't necessarily prevent us from computing PN.
+    SmallVector<std::pair<PHINode *, Constant *>, 8> PHIsToCompute;
     for (DenseMap<Instruction *, Constant *>::const_iterator
            I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
       PHINode *PHI = dyn_cast<PHINode>(I->first);
       if (!PHI || PHI == PN || PHI->getParent() != Header) continue;
+      PHIsToCompute.push_back(std::make_pair(PHI, I->second));
+    }
+    // We use two distinct loops because EvaluateExpression may invalidate any
+    // iterators into CurrentIterVals.
+    for (SmallVectorImpl<std::pair<PHINode *, Constant*> >::const_iterator
+             I = PHIsToCompute.begin(), E = PHIsToCompute.end(); I != E; ++I) {
+      PHINode *PHI = I->first;
       Constant *&NextPHI = NextIterVals[PHI];
       if (!NextPHI) {   // Not already computed.
         Value *BEValue = PHI->getIncomingValue(SecondIsBackedge);
@@ -4928,10 +4936,20 @@
 
     // Update all the PHI nodes for the next iteration.
     DenseMap<Instruction *, Constant *> NextIterVals;
+
+    // Create a list of which PHIs we need to compute. We want to do this before
+    // calling EvaluateExpression on them because that may invalidate iterators
+    // into CurrentIterVals.
+    SmallVector<PHINode *, 8> PHIsToCompute;
     for (DenseMap<Instruction *, Constant *>::const_iterator
            I = CurrentIterVals.begin(), E = CurrentIterVals.end(); I != E; ++I){
       PHINode *PHI = dyn_cast<PHINode>(I->first);
       if (!PHI || PHI->getParent() != Header) continue;
+      PHIsToCompute.push_back(PHI);
+    }
+    for (SmallVectorImpl<PHINode *>::const_iterator I = PHIsToCompute.begin(),
+             E = PHIsToCompute.end(); I != E; ++I) {
+      PHINode *PHI = *I;
       Constant *&NextPHI = NextIterVals[PHI];
       if (NextPHI) continue;    // Already computed!
 

Added: llvm/trunk/test/Transforms/LoopUnroll/pr11361.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/pr11361.ll?rev=144454&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/pr11361.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/pr11361.ll Fri Nov 11 21:09:12 2011
@@ -0,0 +1,42 @@
+; RUN: opt -loop-unroll -disable-output
+; PR11361
+
+; This tests for an iterator invalidation issue.
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @func_1() nounwind uwtable {
+entry:
+  br label %for.cond8.preheader
+
+for.cond8.preheader:                              ; preds = %for.inc15, %entry
+  %l_1264.04 = phi i32 [ 0, %entry ], [ %add.i, %for.inc15 ]
+  %l_1330.0.03 = phi i80 [ undef, %entry ], [ %ins.lcssa, %for.inc15 ]
+  br label %for.body9
+
+for.body9:                                        ; preds = %for.body9, %for.cond8.preheader
+  %l_1330.0.12 = phi i80 [ %l_1330.0.03, %for.cond8.preheader ], [ %ins, %for.body9 ]
+  %storemerge1 = phi i32 [ 7, %for.cond8.preheader ], [ %sub, %for.body9 ]
+  %tmp = lshr i80 %l_1330.0.12, 8
+  %tmp1 = trunc i80 %tmp to i8
+  %inc12 = add i8 %tmp1, 1
+  %tmp2 = zext i8 %inc12 to i80
+  %tmp3 = shl nuw nsw i80 %tmp2, 8
+  %mask = and i80 %l_1330.0.12, -65281
+  %ins = or i80 %tmp3, %mask
+  %sub = add nsw i32 %storemerge1, -1
+  %tobool = icmp eq i32 %sub, 0
+  br i1 %tobool, label %for.inc15, label %for.body9
+
+for.inc15:                                        ; preds = %for.body9
+  %ins.lcssa = phi i80 [ %ins, %for.body9 ]
+  %sext = shl i32 %l_1264.04, 24
+  %conv.i = ashr exact i32 %sext, 24
+  %add.i = add nsw i32 %conv.i, 1
+  %cmp = icmp slt i32 %add.i, 3
+  br i1 %cmp, label %for.cond8.preheader, label %for.end16
+
+for.end16:                                        ; preds = %for.inc15
+  ret void
+}