diff options
| author | Will Dietz <wdietz2@illinois.edu> | 2012-12-15 01:39:14 +0000 |
|---|---|---|
| committer | Will Dietz <wdietz2@illinois.edu> | 2012-12-15 01:39:14 +0000 |
| commit | 1bdbe4d23ed90f601772edd4aa00b8d757c6d6ca (patch) | |
| tree | e87075656dce942f24b16c0ec51f8f847b0eb0be | |
| parent | 3115f5b67e31f50682457883f3864fce2feba1db (diff) | |
[ubsan] Emit branch weight metadata to hint towards common case.
Results in better block placement that helps close the
performance gap when making ubsan checks recoverable.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@170263 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/CodeGen/CGExpr.cpp | 10 | ||||
| -rw-r--r-- | test/CodeGen/catch-undef-behavior.c | 6 |
2 files changed, 13 insertions, 3 deletions
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp index d74ae88990..0be483a907 100644 --- a/lib/CodeGen/CGExpr.cpp +++ b/lib/CodeGen/CGExpr.cpp @@ -1973,7 +1973,15 @@ void CodeGenFunction::EmitCheck(llvm::Value *Checked, StringRef CheckName, llvm::BasicBlock *Cont = createBasicBlock("cont"); llvm::BasicBlock *Handler = createBasicBlock("handler." + CheckName); - Builder.CreateCondBr(Checked, Cont, Handler); + + llvm::Instruction *Branch = Builder.CreateCondBr(Checked, Cont, Handler); + + // Give hint that we very much don't expect to execute the handler + // Value chosen to match UR_NONTAKEN_WEIGHT, see BranchProbabilityInfo.cpp + llvm::MDBuilder MDHelper(getLLVMContext()); + llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1); + Branch->setMetadata(llvm::LLVMContext::MD_prof, Node); + EmitBlock(Handler); llvm::Constant *Info = llvm::ConstantStruct::getAnon(StaticArgs); diff --git a/test/CodeGen/catch-undef-behavior.c b/test/CodeGen/catch-undef-behavior.c index 088e3a9e0f..302ff2ee49 100644 --- a/test/CodeGen/catch-undef-behavior.c +++ b/test/CodeGen/catch-undef-behavior.c @@ -38,7 +38,7 @@ void foo() { // CHECK-NEXT: %[[CHECK2:.*]] = icmp eq i64 %[[MISALIGN]], 0 // CHECK: %[[OK:.*]] = and i1 %[[CHECK01]], %[[CHECK2]] - // CHECK-NEXT: br i1 %[[OK]] + // CHECK-NEXT: br i1 %[[OK]], {{.*}} !prof ![[WEIGHT_MD:.*]] // CHECK: %[[ARG:.*]] = ptrtoint {{.*}} %[[PTR]] to i64 // CHECK-NEXT: call void @__ubsan_handle_type_mismatch_abort(i8* bitcast ({{.*}} @[[LINE_100]] to i8*), i64 %[[ARG]]) noreturn nounwind @@ -85,7 +85,7 @@ int lsh_overflow(int a, int b) { // CHECK: %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]] // CHECK-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]] // CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0 - // CHECK-NEXT: br i1 %[[NO_OVERFLOW]] + // CHECK-NEXT: br i1 %[[NO_OVERFLOW]], {{.*}} !prof ![[WEIGHT_MD]] // CHECK: %[[ARG1:.*]] = zext // CHECK-NEXT: %[[ARG2:.*]] = zext @@ -254,3 +254,5 @@ _Bool sour_bool(_Bool *p) { // CHECK: call void @__ubsan_handle_load_invalid_value_abort(i8* bitcast ({{.*}}), i64 {{.*}}) return *p; } + +// CHECK: ![[WEIGHT_MD]] = metadata !{metadata !"branch_weights", i32 1048575, i32 1} |