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[asan] Fix invalid debug info for promotable allocas

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Since r230724 ("Skip promotable allocas to improve performance at -O0"), there is a regression in the generated debug info for those non-instrumented variables. When inspecting such a variable's value in LLDB, you often get garbage instead of the actual value. ASan instrumentation is inserted before the creation of the non-instrumented alloca. The only allocas that are considered standard stack variables are the ones declared in the first basic-block, but the initial instrumentation setup in the function breaks that invariant.

This patch makes sure uninstrumented allocas stay in the first BB.

Differential Revision: http://reviews.llvm.org/D11179



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242510 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kuba Brecka 2015-07-17 06:29:57 +00:00
parent ac018543f8
commit d71b7d01e8
2 changed files with 33 additions and 1 deletions
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8
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -525,6 +525,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
ShadowMapping Mapping;
SmallVector<AllocaInst *, 16> AllocaVec;
SmallVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
SmallVector<Instruction *, 8> RetVec;
unsigned StackAlignment;
@ -625,7 +626,10 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
/// \brief Collect Alloca instructions we want (and can) handle.
void visitAllocaInst(AllocaInst &AI) {
if (!ASan.isInterestingAlloca(AI)) return;
if (!ASan.isInterestingAlloca(AI)) {
if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.push_back(&AI);
return;
}
StackAlignment = std::max(StackAlignment, AI.getAlignment());
if (ASan.isDynamicAlloca(AI))
@ -1734,6 +1738,8 @@ void FunctionStackPoisoner::poisonStack() {
IRBuilder<> IRB(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation);
for (auto *AI : NonInstrumentedStaticAllocaVec) AI->moveBefore(InsBefore);
SmallVector<ASanStackVariableDescription, 16> SVD;
SVD.reserve(AllocaVec.size());
for (AllocaInst *AI : AllocaVec) {

26
test/Instrumentation/AddressSanitizer/debug_info_noninstrumented_alloca.ll Normal file
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@ -0,0 +1,26 @@
; This test checks that non-instrumented allocas stay in the first basic block.
; Only first-basic-block allocas are considered stack slots, and moving them
; breaks debug info.
; RUN: opt < %s -asan -asan-module -S | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.10.0"
define i32 @foo() sanitize_address {
entry:
; Regular alloca, will get instrumented (forced by the ptrtoint below).
%instrumented = alloca i32, align 4
; Won't be instrumented because of asan-skip-promotable-allocas.
%non_instrumented = alloca i32, align 4
store i32 0, i32* %non_instrumented, align 4
%value = load i32, i32* %non_instrumented, align 4
%ptr = ptrtoint i32* %instrumented to i64
ret i32 %value
}
; CHECK: entry:
; CHECK: %non_instrumented = alloca i32, align 4
; CHECK: load i32, i32* @__asan_option_detect_stack_use_after_return