https://github.com/vitalybuka created
https://github.com/llvm/llvm-project/pull/84214
With #83470 it reduces UBSAN overhead from 52.5% to 12.6%.
Measured as "Geomean difference" on "test-suite/MultiSource/Benchmarks"
with PGO+ThinLTO build.
On real server apps we see 95% of code instrumented, with 10% -> 1.5%
UBSAN overhead improvements. We can pass this test only with subset of
UBSAN, so base overhead is smaller.
We have followup patches to improve it even further.
>From f915a90962986cf20a9903ac9995cfee3b8ba990 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalyb...@google.com>
Date: Wed, 6 Mar 2024 10:03:46 -0800
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
=?UTF-8?q?l=20version?=
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Created using spr 1.3.4
---
clang/lib/CodeGen/BackendUtil.cpp | 17 +++++++++++++++++
clang/test/CodeGen/remote-traps.cpp | 15 +++++++++++++++
2 files changed, 32 insertions(+)
create mode 100644 clang/test/CodeGen/remote-traps.cpp
diff --git a/clang/lib/CodeGen/BackendUtil.cpp
b/clang/lib/CodeGen/BackendUtil.cpp
index 056f790d41853d..6f9aa262f3d51e 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -76,6 +76,7 @@
#include "llvm/Transforms/Instrumentation/MemProfiler.h"
#include "llvm/Transforms/Instrumentation/MemorySanitizer.h"
#include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
+#include "llvm/Transforms/Instrumentation/RemoveTrapsPass.h"
#include "llvm/Transforms/Instrumentation/SanitizerBinaryMetadata.h"
#include "llvm/Transforms/Instrumentation/SanitizerCoverage.h"
#include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
@@ -83,6 +84,7 @@
#include "llvm/Transforms/Scalar/EarlyCSE.h"
#include "llvm/Transforms/Scalar/GVN.h"
#include "llvm/Transforms/Scalar/JumpThreading.h"
+#include "llvm/Transforms/Scalar/SimplifyCFG.h"
#include "llvm/Transforms/Utils/Debugify.h"
#include "llvm/Transforms/Utils/EntryExitInstrumenter.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
@@ -98,6 +100,10 @@ using namespace llvm;
namespace llvm {
extern cl::opt<bool> PrintPipelinePasses;
+cl::opt<bool> ClRemoveTraps("clang-remove-traps", cl::Optional,
+ cl::desc("Insert remove-traps pass."),
+ cl::init(false));
+
// Experiment to move sanitizers earlier.
static cl::opt<bool> ClSanitizeOnOptimizerEarlyEP(
"sanitizer-early-opt-ep", cl::Optional,
@@ -743,6 +749,17 @@ static void addSanitizers(const Triple &TargetTriple,
// LastEP does not need GlobalsAA.
PB.registerOptimizerLastEPCallback(SanitizersCallback);
}
+
+ if (ClRemoveTraps) {
+ PB.registerOptimizerEarlyEPCallback([&](ModulePassManager &MPM,
+ OptimizationLevel Level) {
+ FunctionPassManager FPM;
+ FPM.addPass(RemoveTrapsPass());
+ FPM.addPass(
+
SimplifyCFGPass(SimplifyCFGOptions().convertSwitchRangeToICmp(true)));
+ MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
+ });
+ }
}
void EmitAssemblyHelper::RunOptimizationPipeline(
diff --git a/clang/test/CodeGen/remote-traps.cpp
b/clang/test/CodeGen/remote-traps.cpp
new file mode 100644
index 00000000000000..7d4eb76a7d81e9
--- /dev/null
+++ b/clang/test/CodeGen/remote-traps.cpp
@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -O1 -emit-llvm -fsanitize=signed-integer-overflow
-fsanitize-trap=signed-integer-overflow %s -o - | FileCheck %s
+// RUN: %clang_cc1 -O1 -emit-llvm -fsanitize=signed-integer-overflow
-fsanitize-trap=signed-integer-overflow -mllvm -clang-remove-traps -mllvm
-remove-traps-random-rate=1 %s -o - | FileCheck %s --implicit-check-not="call
void @llvm.ubsantrap" --check-prefixes=REMOVE
+
+int f(int x) {
+ return x + 123;
+}
+
+// CHECK-LABEL: define dso_local noundef i32 @_Z1fi(
+// CHECK: call { i32, i1 } @llvm.sadd.with.overflow.i32(
+// CHECK: trap:
+// CHECK-NEXT: call void @llvm.ubsantrap(i8 0)
+// CHECK-NEXT: unreachable, !nosanitize !2
+
+// REMOVE-LABEL: define dso_local noundef i32 @_Z1fi(
+// REMOVE: call { i32, i1 } @llvm.sadd.with.overflow.i32(
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