From 472fdf7090bb00af3a3f9dcbe22263120a527533 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sat, 20 Mar 2010 03:53:53 +0000 Subject: [PATCH] Clear the SCEVExpander's insertion point after making deletions, so that the SCEVExpander doesn't retain a dangling pointer as its insert position. The dangling pointer in this case wasn't ever used to insert new instructions, but it was causing trouble with SCEVExpander's code for automatically advancing its insert position past debug intrinsics. This fixes use-after-free errors that valgrind noticed in test/Transforms/IndVarSimplify/2007-06-06-DeleteDanglesPtr.ll and test/Transforms/IndVarSimplify/exit_value_tests.ll. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99036 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/ScalarEvolutionExpander.h | 7 +++++++ lib/Transforms/Scalar/IndVarSimplify.cpp | 4 ++++ 2 files changed, 11 insertions(+) diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h index 828709404b1..dc9b73bd566 100644 --- a/include/llvm/Analysis/ScalarEvolutionExpander.h +++ b/include/llvm/Analysis/ScalarEvolutionExpander.h @@ -104,6 +104,13 @@ namespace llvm { /// is useful for late optimization passes. void disableCanonicalMode() { CanonicalMode = false; } + /// clearInsertPoint - Clear the current insertion point. This is useful + /// if the instruction that had been serving as the insertion point may + /// have been deleted. + void clearInsertPoint() { + Builder.ClearInsertionPoint(); + } + private: LLVMContext &getContext() const { return SE.getContext(); } diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index de93e9f621f..eb04d9401fb 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -307,6 +307,10 @@ void IndVarSimplify::RewriteLoopExitValues(Loop *L, } } } + + // The insertion point instruction may have been deleted; clear it out + // so that the rewriter doesn't trip over it later. + Rewriter.clearInsertPoint(); } void IndVarSimplify::RewriteNonIntegerIVs(Loop *L) { -- 2.34.1