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[asan] Assign a low branch weight to ASan's slow path, patch by Jonas Wagner. This speeds up asan (at least on SPEC) by 1%-5% or more. Also fix lint in dfsan.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216972 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kostya Serebryany 2014-09-02 21:46:51 +00:00
parent 2aab51a118
commit 891198b358
3 changed files with 8 additions and 3 deletions
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5
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -870,8 +870,11 @@ void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
TerminatorInst *CrashTerm = nullptr;
if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
// We use branch weights for the slow path check, to indicate that the slow
// path is rarely taken. This seems to be the case for SPEC benchmarks.
TerminatorInst *CheckTerm =
SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
MDBuilder(*C).createBranchWeights(1, 100000));
assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
BasicBlock *NextBB = CheckTerm->getSuccessor(0);
IRB.SetInsertPoint(CheckTerm);

2
lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
View File

@ -139,7 +139,7 @@ class DFSanABIList {
std::unique_ptr<SpecialCaseList> SCL;
public:
DFSanABIList(std::unique_ptr<SpecialCaseList> SCL) : SCL(std::move(SCL)) {}
DFSanABIList(std::unique_ptr<SpecialCaseList> SCL) : SCL(std::move(SCL)) {}
/// Returns whether either this function or its source file are listed in the
/// given category.

4
test/Instrumentation/AddressSanitizer/basic.ll
View File

@ -14,7 +14,7 @@ define i32 @test_load(i32* %a) sanitize_address {
; CHECK: %[[LOAD_SHADOW_PTR:[^ ]*]] = inttoptr
; CHECK: %[[LOAD_SHADOW:[^ ]*]] = load i8* %[[LOAD_SHADOW_PTR]]
; CHECK: icmp ne i8
; CHECK: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}
; CHECK: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}!prof ![[PROF:[0-9]+]]
;
; First instrumentation block refines the shadow test.
; CHECK: and i64 %[[LOAD_ADDR]], 7
@ -169,3 +169,5 @@ define void @memintr_test(i8* %a, i8* %b) nounwind uwtable sanitize_address {
; CHECK: __asan_memcpy
; CHECK: ret void
; PROF
; CHECK: ![[PROF]] = metadata !{metadata !"branch_weights", i32 1, i32 100000}