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

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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
This commit is contained in:
Torok Edwin 2009-05-24 14:23:16 +00:00
parent ed2f8c557a
commit b679de2a21
4 changed files with 45 additions and 2 deletions
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2
include/llvm/Analysis/ScalarEvolutionExpander.h
View File

@ -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;

2
lib/Analysis/ScalarEvolutionExpander.cpp
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@ -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;

2
lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -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)

41
test/Transforms/IndVarSimplify/2009-05-24-useafterfree.ll Normal file
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@ -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
}