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[asan] Improve moving of non-instrumented allocas

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In r242510, non-instrumented allocas are now moved into the first basic block.  This patch limits that to only move allocas that are present *after* the first instrumented one (i.e. only move allocas up).  A testcase was updated to show behavior in these two cases.  Without the patch, an alloca could be moved down, and could cause an invalid IR.

Differential Revision: http://reviews.llvm.org/D11339



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242883 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kuba Brecka
2015-07-22 10:25:38 +00:00
parent f020cb2f75
commit a5812d5bbf
2 changed files with 31 additions and 12 deletions
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18
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@@ -18,6 +18,7 @@
#include "llvm/ADT/DenseMap.h" #include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h" #include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/DepthFirstIterator.h" #include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h" #include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h" #include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h" #include "llvm/ADT/SmallVector.h"
@@ -538,7 +539,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
ShadowMapping Mapping; ShadowMapping Mapping;
SmallVector<AllocaInst *, 16> AllocaVec; SmallVector<AllocaInst *, 16> AllocaVec;
SmallVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec; SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
SmallVector<Instruction *, 8> RetVec; SmallVector<Instruction *, 8> RetVec;
unsigned StackAlignment; unsigned StackAlignment;
@@ -641,7 +642,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
/// \brief Collect Alloca instructions we want (and can) handle. /// \brief Collect Alloca instructions we want (and can) handle.
void visitAllocaInst(AllocaInst &AI) { void visitAllocaInst(AllocaInst &AI) {
if (!ASan.isInterestingAlloca(AI)) { if (!ASan.isInterestingAlloca(AI)) {
if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.push_back(&AI); if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
return; return;
} }
@@ -1787,10 +1788,15 @@ void FunctionStackPoisoner::poisonStack() {
IRBuilder<> IRB(InsBefore); IRBuilder<> IRB(InsBefore);
IRB.SetCurrentDebugLocation(EntryDebugLocation); IRB.SetCurrentDebugLocation(EntryDebugLocation);
// Make sure non-instrumented allocas stay in the first basic block. // Make sure non-instrumented allocas stay in the entry block. Otherwise,
// Otherwise, debug info is broken, because only first-basic-block allocas are // debug info is broken, because only entry-block allocas are treated as
// treated as regular stack slots. // regular stack slots.
for (auto *AI : NonInstrumentedStaticAllocaVec) AI->moveBefore(InsBefore); auto InsBeforeB = InsBefore->getParent();
assert(InsBeforeB == &F.getEntryBlock());
for (BasicBlock::iterator I = InsBefore; I != InsBeforeB->end(); ++I)
if (auto *AI = dyn_cast_or_null<AllocaInst>(I))
if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
AI->moveBefore(InsBefore);
// If we have a call to llvm.localescape, keep it in the entry block. // If we have a call to llvm.localescape, keep it in the entry block.
if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore); if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);

25
test/Instrumentation/AddressSanitizer/debug_info_noninstrumented_alloca.ll
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@@ -9,18 +9,31 @@ target triple = "x86_64-apple-macosx10.10.0"
define i32 @foo() sanitize_address { define i32 @foo() sanitize_address {
entry: entry:
; Won't be instrumented because of asan-skip-promotable-allocas.
%non_instrumented1 = alloca i32, align 4
; Regular alloca, will get instrumented (forced by the ptrtoint below). ; Regular alloca, will get instrumented (forced by the ptrtoint below).
%instrumented = alloca i32, align 4 %instrumented = alloca i32, align 4
; Won't be instrumented because of asan-skip-promotable-allocas. ; Won't be instrumented because of asan-skip-promotable-allocas.
%non_instrumented = alloca i32, align 4 %non_instrumented2 = 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 br label %bb0
ret i32 %value
bb0:
; Won't be instrumented because of asan-skip-promotable-allocas.
%non_instrumented3 = alloca i32, align 4
%ptr = ptrtoint i32* %instrumented to i32
br label %bb1
bb1:
ret i32 %ptr
} }
; CHECK: entry: ; CHECK: entry:
; CHECK: %non_instrumented = alloca i32, align 4 ; CHECK: %non_instrumented1 = alloca i32, align 4
; CHECK: %non_instrumented2 = alloca i32, align 4
; CHECK: load i32, i32* @__asan_option_detect_stack_use_after_return ; CHECK: load i32, i32* @__asan_option_detect_stack_use_after_return
; CHECK: bb0:
; CHECK: %non_instrumented3 = alloca i32, align 4