The rewriter may hold references to instructions that are deleted because they are...

Fix by clearing the rewriter cache before deleting the trivially dead
instructions.
Also make InsertedExpressions use an AssertingVH to catch these
bugs easier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72364 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h
index cf2ad10e25af343fba3c8156c4beec47f89bf532..8194555cdebf070fda753cdfe6e8f91bca716c88 100644 (file)
--- a/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -28,7 +28,7 @@ namespace llvm {
   /// memory.
   struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
     ScalarEvolution &SE;
-    std::map<SCEVHandle, Value*> InsertedExpressions;
+    std::map<SCEVHandle, AssertingVH<Value> > InsertedExpressions;
     std::set<Value*> InsertedValues;
 
     BasicBlock::iterator InsertPt;

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 507ced74fd1e889393c3adb38e69a82fe3b00abc..fc66ddb6f485742a7515d8c2e4e5b566c1f8cd90 100644 (file)
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -526,7 +526,7 @@ Value *SCEVExpander::expandCodeFor(SCEVHandle SH, const Type *Ty) {
 
 Value *SCEVExpander::expand(const SCEV *S) {
   // Check to see if we already expanded this.
-  std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
+  std::map<SCEVHandle, AssertingVH<Value> >::iterator I = InsertedExpressions.find(S);
   if (I != InsertedExpressions.end())
     return I->second;
   

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 89742c55d64d4f74d62040ccdbc063588f72ff46..670499062ec5d56ee125d54149cf6ef4323b7d3e 100644 (file)
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -298,6 +298,7 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L,
         // in the loop, so we don't need an LCSSA phi node anymore.
         if (NumPreds == 1) {
           PN->replaceAllUsesWith(ExitVal);
+          Rewriter.clear();
           RecursivelyDeleteTriviallyDeadInstructions(PN);
           break;
         }
@@ -418,6 +419,7 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
   // Reorder instructions to avoid use-before-def conditions.
   FixUsesBeforeDefs(L, Rewriter);
 
+  Rewriter.clear();
   // For completeness, inform IVUsers of the IV use in the newly-created
   // loop exit test instruction.
   if (NewICmp)

diff --git a/test/Transforms/IndVarSimplify/2009-05-24-useafterfree.ll b/test/Transforms/IndVarSimplify/2009-05-24-useafterfree.ll
new file mode 100644 (file)
index 0000000..ecbb231
--- /dev/null
+++ b/test/Transforms/IndVarSimplify/2009-05-24-useafterfree.ll
@@ -0,0 +1,41 @@
+; RUN: llvm-as < %s | opt -indvars
+; PR4258
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+target triple = "i386-linux-gnu"
+
+define void @0(i32*, i32*, i32, i32) nounwind {
+       br i1 false, label %bb.nph1.preheader, label %.outer._crit_edge
+
+bb.nph1.preheader:             ; preds = %4
+       %smax = select i1 false, i32 -1, i32 0          ; <i32> [#uses=1]
+       %tmp12 = sub i32 0, %smax               ; <i32> [#uses=1]
+       br label %bb.nph1
+
+bb.nph1:               ; preds = %.outer, %bb.nph1.preheader
+       br i1 false, label %bb.nph3.preheader, label %.outer
+
+bb.nph3.preheader:             ; preds = %bb.nph1
+       br label %bb.nph3
+
+bb.nph3:               ; preds = %bb.nph3, %bb.nph3.preheader
+       %indvar7 = phi i32 [ %indvar.next8, %bb.nph3 ], [ 0, %bb.nph3.preheader ]               ; <i32> [#uses=3]
+       %tmp9 = mul i32 %indvar7, -1            ; <i32> [#uses=1]
+       %tmp13 = add i32 %tmp9, %tmp12          ; <i32> [#uses=1]
+       %tmp14 = add i32 %tmp13, -2             ; <i32> [#uses=1]
+       %5 = icmp sgt i32 %tmp14, 0             ; <i1> [#uses=1]
+       %indvar.next8 = add i32 %indvar7, 1             ; <i32> [#uses=1]
+       br i1 %5, label %bb.nph3, label %.outer.loopexit
+
+.outer.loopexit:               ; preds = %bb.nph3
+       %indvar7.lcssa = phi i32 [ %indvar7, %bb.nph3 ]         ; <i32> [#uses=0]
+       br label %.outer
+
+.outer:                ; preds = %.outer.loopexit, %bb.nph1
+       br i1 false, label %bb.nph1, label %.outer._crit_edge.loopexit
+
+.outer._crit_edge.loopexit:            ; preds = %.outer
+       br label %.outer._crit_edge
+
+.outer._crit_edge:             ; preds = %.outer._crit_edge.loopexit, %4
+       ret void
+}