[clang] [clang] Add optional pass to remove UBSAN traps using PGO (PR #84214)

[Vitaly Buka via cfe-commits]

https://github.com/vitalybuka updated https://github.com/llvm/llvm-project/pull/84214

>From f915a90962986cf20a9903ac9995cfee3b8ba990 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Wed, 6 Mar 2024 10:03:46 -0800
Subject: [PATCH 1/2] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20in?=
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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(

>From 8c5ad5c16d1826e29d4daf67baaa99607b15453f Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka at google.com>
Date: Wed, 6 Mar 2024 10:08:47 -0800
Subject: [PATCH 2/2] comment

Created using spr 1.3.4
---
 clang/lib/CodeGen/BackendUtil.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 6f9aa262f3d51e..3293699838a622 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -751,6 +751,9 @@ static void addSanitizers(const Triple &TargetTriple,
   }
 
   if (ClRemoveTraps) {
+    // We can optimize after inliner, and PGO profile matching, which are part
+    // of `buildModuleSimplificationPipeline`. The hook below is called after
+    // that, from `buildModuleOptimizationPipeline`.
     PB.registerOptimizerEarlyEPCallback([&](ModulePassManager &MPM,
                                             OptimizationLevel Level) {
       FunctionPassManager FPM;