[ubsan] Remove -ubsan-unique-traps (replace with -fno-sanitize-merge)

-fno-sanitize-merge (introduced in #120511) duplicates the functionality of -ubsan-unique-traps but also allows individual checks to be specified e.g.,
* "-fno-sanitize-merge" without arguments is equivalent to -ubsan-unique-traps
* "-fno-sanitize-merge=bool,enum" will apply it only to those two checks

This patch also adds negative test examples to bounds-checking.c, and
strengthens the NOOPTARRAY assertion to prevent spurious matches.

Note: this change necessarily breaks compatibility with '-mllvm
-ubsan-unique-traps'. We hope that this is acceptable since '-mllvm
-ubsan-unique-traps' was an experimental flag.

"-bounds-checking-unique-traps" is unaffected by this patch.

Author: thurstond

clang/lib/CodeGen/CGExpr.cpp

@@ -52,11 +52,6 @@
 using namespace clang;
 using namespace CodeGen;
 
-// Experiment to make sanitizers easier to debug
-static llvm::cl::opt<bool> ClSanitizeDebugDeoptimization(
-    "ubsan-unique-traps", llvm::cl::Optional,
-    llvm::cl::desc("Deoptimize traps for UBSAN so there is 1 trap per check."));
-
 // TODO: Introduce frontend options to enabled per sanitizers, similar to
 // `fsanitize-trap`.
 static llvm::cl::opt<bool> ClSanitizeGuardChecks(
@@ -3581,7 +3576,7 @@ static void emitCheckHandlerCall(CodeGenFunction &CGF,
                                llvm::AttributeList::FunctionIndex, B),
       /*Local=*/true);
   llvm::CallInst *HandlerCall = CGF.EmitNounwindRuntimeCall(Fn, FnArgs);
-  NoMerge = NoMerge || ClSanitizeDebugDeoptimization ||
+  NoMerge = NoMerge ||
             !CGF.CGM.getCodeGenOpts().OptimizationLevel ||
             (CGF.CurCodeDecl && CGF.CurCodeDecl->hasAttr<OptimizeNoneAttr>());
   if (NoMerge)
@@ -3915,7 +3910,7 @@ void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked,
 
   llvm::BasicBlock *&TrapBB = TrapBBs[CheckHandlerID];
 
-  NoMerge = NoMerge || ClSanitizeDebugDeoptimization ||
+  NoMerge = NoMerge ||
             !CGM.getCodeGenOpts().OptimizationLevel ||
             (CurCodeDecl && CurCodeDecl->hasAttr<OptimizeNoneAttr>());
 

clang/test/CodeGen/bounds-checking.c

@@ -1,7 +1,15 @@
-// RUN: %clang_cc1 -fsanitize=local-bounds -emit-llvm -triple x86_64-apple-darwin10 %s -o - | FileCheck %s
-// RUN: %clang_cc1 -fsanitize=array-bounds -O -fsanitize-trap=array-bounds -emit-llvm -triple x86_64-apple-darwin10 -DNO_DYNAMIC %s -o - | FileCheck %s
-// RUN: %clang_cc1 -fsanitize=local-bounds -fsanitize-trap=local-bounds -O3 -mllvm -bounds-checking-unique-traps -emit-llvm -triple x86_64-apple-darwin10 %s -o - | FileCheck %s --check-prefixes=NOOPTLOCAL
-// RUN: %clang_cc1 -fsanitize=array-bounds -fsanitize-trap=array-bounds -O3 -mllvm -ubsan-unique-traps -emit-llvm -triple x86_64-apple-darwin10 %s -o - | FileCheck %s --check-prefixes=NOOPTARRAY
+// RUN: %clang_cc1 -fsanitize=local-bounds                                 -emit-llvm -triple x86_64-apple-darwin10              %s -o - |     FileCheck %s
+// RUN: %clang_cc1 -fsanitize=array-bounds -O                              -emit-llvm -triple x86_64-apple-darwin10 %s -o -              | not FileCheck %s
+// RUN: %clang_cc1 -fsanitize=array-bounds -O -fsanitize-trap=array-bounds -emit-llvm -triple x86_64-apple-darwin10 -DNO_DYNAMIC %s -o - |     FileCheck %s
+//
+// RUN: %clang_cc1 -fsanitize=local-bounds -fsanitize-trap=local-bounds -O3 -mllvm -bounds-checking-unique-traps -emit-llvm -triple x86_64-apple-darwin10 %s -o - |     FileCheck %s --check-prefixes=NOOPTLOCAL
+// RUN: %clang_cc1 -fsanitize=local-bounds -fsanitize-trap=local-bounds -O3                                      -emit-llvm -triple x86_64-apple-darwin10 %s -o - | not FileCheck %s --check-prefixes=NOOPTLOCAL
+//
+// N.B. The clang driver defaults to -fsanitize-merge but clang_cc1 effectively
+// defaults to -fno-sanitize-merge.
+// RUN: %clang_cc1 -fsanitize=array-bounds -fsanitize-trap=array-bounds                               -O3 -emit-llvm -triple x86_64-apple-darwin10 %s -o - |     FileCheck %s --check-prefixes=NOOPTARRAY
+// RUN: %clang_cc1 -fsanitize=array-bounds -fsanitize-trap=array-bounds -fno-sanitize-merge           -O3 -emit-llvm -triple x86_64-apple-darwin10 %s -o - |     FileCheck %s --check-prefixes=NOOPTARRAY
+// RUN: %clang_cc1 -fsanitize=array-bounds -fsanitize-trap=array-bounds -fsanitize-merge=array-bounds -O3 -emit-llvm -triple x86_64-apple-darwin10 %s -o - | not FileCheck %s --check-prefixes=NOOPTARRAY
 //
 // REQUIRES: x86-registered-target
 
@@ -43,7 +51,7 @@ int f4(int i) {
   return b[i];
 }
 
-// Union flexible-array memebers are a C99 extension. All array members with a
+// Union flexible-array members are a C99 extension. All array members with a
 // constant size should be considered FAMs.
 
 union U { int a[0]; int b[1]; int c[2]; };
@@ -72,6 +80,10 @@ int f7(union U *u, int i) {
 char B[10];
 char B2[10];
 // CHECK-LABEL: @f8
+// Check the label to prevent spuriously matching ubsantraps from other
+// functions.
+// NOOPTLOCAL-LABEL: @f8
+// NOOPTARRAY-LABEL: @f8
 void f8(int i, int k) {
   // NOOPTLOCAL: call void @llvm.ubsantrap(i8 3)
   // NOOPTARRAY: call void @llvm.ubsantrap(i8 18)

clang/test/CodeGen/ubsan-trap-merge.c

@@ -10,10 +10,6 @@
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 %s -o -                                         | FileCheck %s --check-prefixes=HANDLER-NOMERGE
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 %s -o - -fsanitize-minimal-runtime              | FileCheck %s --check-prefixes=MINRT-NOMERGE
 //
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o - -fsanitize-trap=signed-integer-overflow | FileCheck %s --check-prefixes=TRAP-NOMERGE
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o -                                         | FileCheck %s --check-prefixes=HANDLER-NOMERGE
-// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -mllvm -ubsan-unique-traps %s -o - -fsanitize-minimal-runtime              | FileCheck %s --check-prefixes=MINRT-NOMERGE
-//
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -fno-sanitize-merge=signed-integer-overflow  %s -o - -fsanitize-trap=signed-integer-overflow | FileCheck %s --check-prefixes=TRAP-NOMERGE
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -fno-sanitize-merge=signed-integer-overflow  %s -o -                                         | FileCheck %s --check-prefixes=HANDLER-NOMERGE
 // RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -fsanitize=signed-integer-overflow -O3 -fno-sanitize-merge=signed-integer-overflow  %s -o - -fsanitize-minimal-runtime              | FileCheck %s --check-prefixes=MINRT-NOMERGE