[llvm] r216972 - [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.

[Kostya Serebryany]

Author: kcc
Date: Tue Sep  2 16:46:51 2014
New Revision: 216972

URL: http://llvm.org/viewvc/llvm-project?rev=216972&view=rev
Log:
[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.

Modified:
    llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
    llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
    llvm/trunk/test/Instrumentation/AddressSanitizer/basic.ll

Modified: llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp?rev=216972&r1=216971&r2=216972&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp Tue Sep  2 16:46:51 2014
@@ -870,8 +870,11 @@ void AddressSanitizer::instrumentAddress
   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);

Modified: llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp?rev=216972&r1=216971&r2=216972&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp Tue Sep  2 16:46:51 2014
@@ -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.

Modified: llvm/trunk/test/Instrumentation/AddressSanitizer/basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/AddressSanitizer/basic.ll?rev=216972&r1=216971&r2=216972&view=diff
==============================================================================
--- llvm/trunk/test/Instrumentation/AddressSanitizer/basic.ll (original)
+++ llvm/trunk/test/Instrumentation/AddressSanitizer/basic.ll Tue Sep  2 16:46:51 2014
@@ -14,7 +14,7 @@ define i32 @test_load(i32* %a) sanitize_
 ; 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
 ; CHECK: __asan_memcpy
 ; CHECK: ret void
 
+; PROF
+; CHECK: ![[PROF]] = metadata !{metadata !"branch_weights", i32 1, i32 100000}