From: Kostya Serebryany <kcc@google.com>
Date: Tue, 2 Sep 2014 21:46:51 +0000 (+0000)
Subject: [asan]  Assign a low branch weight to ASan's slow path, patch by Jonas Wagner. This... 
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=891198b358c79d9464bd40d94f5ba6249080741a

[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216972 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 357b5d52608..3ff0a616f4a 100644
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -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);
diff --git a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index f79b2039528..771dcd7d9fe 100644
--- a/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -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.
diff --git a/test/Instrumentation/AddressSanitizer/basic.ll b/test/Instrumentation/AddressSanitizer/basic.ll
index 5436c60cb6d..d9997e2f350 100644
--- a/test/Instrumentation/AddressSanitizer/basic.ll
+++ b/test/Instrumentation/AddressSanitizer/basic.ll
@@ -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}