[clang] Add support for builtin_verbose_trap (PR #79230)
Akira Hatanaka via cfe-commits
cfe-commits at lists.llvm.org
Mon Apr 1 09:33:04 PDT 2024
https://github.com/ahatanak updated https://github.com/llvm/llvm-project/pull/79230
>From 44813fefa59b442abcc6cb23c2ac8d3f78e44efc Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Tue, 16 Jan 2024 13:18:09 -0800
Subject: [PATCH 01/11] Add support for builtin_verbose_trap
The builtin causes the program to stop its execution abnormally and shows a
human-readable description of the reason for the termination when a debugger is
attached or in a symbolicated crash log.
The motivation for the builtin is explained in the following RFC:
https://discourse.llvm.org/t/rfc-adding-builtin-verbose-trap-string-literal/75845
---
clang/docs/LanguageExtensions.rst | 48 ++++++++++++++++++
clang/include/clang/AST/Expr.h | 5 ++
clang/include/clang/Basic/Builtins.td | 6 +++
.../clang/Basic/DiagnosticSemaKinds.td | 2 +
clang/lib/AST/ExprConstant.cpp | 18 +++++--
clang/lib/CodeGen/CGBuiltin.cpp | 12 +++++
clang/lib/CodeGen/CGDebugInfo.cpp | 42 ++++++++++++++++
clang/lib/CodeGen/CGDebugInfo.h | 20 ++++++++
clang/lib/Sema/SemaChecking.cpp | 22 +++++++++
.../CodeGenCXX/debug-info-verbose-trap.cpp | 49 +++++++++++++++++++
clang/test/SemaCXX/verbose-trap.cpp | 28 +++++++++++
11 files changed, 249 insertions(+), 3 deletions(-)
create mode 100644 clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
create mode 100644 clang/test/SemaCXX/verbose-trap.cpp
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 7b23e4d1c2f30c..4e4151e7803875 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -3464,6 +3464,54 @@ Query for this feature with ``__has_builtin(__builtin_trap)``.
``__builtin_arm_trap`` is lowered to the ``llvm.aarch64.break`` builtin, and then to ``brk #payload``.
+``__builtin_verbose_trap``
+--------------------------
+
+``__builtin_verbose_trap`` causes the program to stop its execution abnormally
+and shows a human-readable description of the reason for the termination when a
+debugger is attached or in a symbolicated crash log.
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_verbose_trap(const char *reason)
+
+**Description**
+
+``__builtin_verbose_trap`` is lowered to the ` ``llvm.trap`` <https://llvm.org/docs/LangRef.html#llvm-trap-intrinsic>`_ builtin.
+Additionally, clang emits debug metadata that represents an artificial inline
+frame whose name encodes the string passed to the builtin, prefixed by a "magic"
+prefix.
+
+For example, consider the following code:
+
+.. code-block:: c++
+
+ void foo(int* p) {
+ if (p == nullptr)
+ __builtin_verbose_trap("Argument_must_not_be_null");
+ }
+
+The debug metadata would look as if it were produced for the following code:
+
+.. code-block:: c++
+
+ __attribute__((always_inline))
+ inline void "__llvm_verbose_trap: Argument_must_not_be_null"() {
+ __builtin_trap();
+ }
+
+ void foo(int* p) {
+ if (p == nullptr)
+ "__llvm_verbose_trap: Argument_must_not_be_null"();
+ }
+
+However, the LLVM IR would not actually contain a call to the artificial
+function — it only exists in the debug metadata.
+
+Query for this feature with ``__has_builtin(__builtin_verbose_trap)``.
+
``__builtin_nondeterministic_value``
------------------------------------
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 6e153ebe024b42..789bedbd9724a6 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -787,6 +787,11 @@ class Expr : public ValueStmt {
const Expr *PtrExpression, ASTContext &Ctx,
EvalResult &Status) const;
+ /// If the current Expr can be evaluated to a pointer to a null-terminated
+ /// constant string, return the constant string (without the terminating null)
+ /// in Result. Return true if it succeeds.
+ bool tryEvaluateString(std::string &Result, ASTContext &Ctx) const;
+
/// Enumeration used to describe the kind of Null pointer constant
/// returned from \c isNullPointerConstant().
enum NullPointerConstantKind {
diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index f421223ff087de..df7b0460c1f21d 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -1152,6 +1152,12 @@ def Trap : Builtin {
let Prototype = "void()";
}
+def VerboseTrap : Builtin {
+ let Spellings = ["__builtin_verbose_trap"];
+ let Attributes = [NoThrow, NoReturn];
+ let Prototype = "void(char const*)";
+}
+
def Debugtrap : Builtin {
let Spellings = ["__builtin_debugtrap"];
let Attributes = [NoThrow];
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index df57f5e6ce11ba..03f52c88ea1f1f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8863,6 +8863,8 @@ def err_expected_callable_argument : Error<
"expected a callable expression as %ordinal0 argument to %1, found %2">;
def note_building_builtin_dump_struct_call : Note<
"in call to printing function with arguments '(%0)' while dumping struct">;
+def err_builtin_verbose_trap_arg : Error<
+ "argument to __builtin_verbose_trap must be a non-empty string literal">;
def err_atomic_load_store_uses_lib : Error<
"atomic %select{load|store}0 requires runtime support that is not "
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index dae8f32fc02951..127c0415f8feb8 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -1884,7 +1884,8 @@ static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
- EvalInfo &Info);
+ EvalInfo &Info,
+ std::string *StringResult = nullptr);
/// Evaluate an integer or fixed point expression into an APResult.
static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
@@ -16789,7 +16790,7 @@ bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
}
static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
- EvalInfo &Info) {
+ EvalInfo &Info, std::string *StringResult) {
if (!E->getType()->hasPointerRepresentation() || !E->isPRValue())
return false;
@@ -16816,6 +16817,8 @@ static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
Str = Str.substr(0, Pos);
Result = Str.size();
+ if (StringResult)
+ *StringResult = Str;
return true;
}
@@ -16831,12 +16834,21 @@ static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
if (!Char.getInt()) {
Result = Strlen;
return true;
- }
+ } else if (StringResult)
+ StringResult->push_back(Char.getInt().getExtValue());
if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
return false;
}
}
+bool Expr::tryEvaluateString(std::string &StringResult, ASTContext &Ctx) const {
+ Expr::EvalStatus Status;
+ EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
+ uint64_t Result;
+
+ return EvaluateBuiltinStrLen(this, Result, Info, &StringResult);
+}
+
bool Expr::EvaluateCharRangeAsString(std::string &Result,
const Expr *SizeExpression,
const Expr *PtrExpression, ASTContext &Ctx,
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index bb007231c0b783..b9307331fc56c8 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3574,6 +3574,18 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
case Builtin::BI__builtin_trap:
EmitTrapCall(Intrinsic::trap);
return RValue::get(nullptr);
+ case Builtin::BI__builtin_verbose_trap: {
+ llvm::DILocation *TrapLocation = Builder.getCurrentDebugLocation();
+ if (getDebugInfo()) {
+ std::string Str;
+ E->getArg(0)->tryEvaluateString(Str, getContext());
+ TrapLocation = getDebugInfo()->CreateTrapFailureMessageFor(
+ TrapLocation, "__llvm_verbose_trap", Str);
+ }
+ ApplyDebugLocation ApplyTrapDI(*this, TrapLocation);
+ EmitTrapCall(Intrinsic::trap);
+ return RValue::get(nullptr);
+ }
case Builtin::BI__debugbreak:
EmitTrapCall(Intrinsic::debugtrap);
return RValue::get(nullptr);
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 691fde8b0d8b82..81bb2854b80d3b 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1631,6 +1631,27 @@ llvm::DIType *CGDebugInfo::createFieldType(
offsetInBits, flags, debugType, Annotations);
}
+llvm::DISubprogram *
+CGDebugInfo::getFakeFuncSubprogram(const std::string &FakeFuncName) {
+ llvm::DISubprogram *&SP = FakeFuncMap[FakeFuncName];
+
+ if (!SP) {
+ auto FileScope = TheCU->getFile();
+ llvm::DISubroutineType *DIFnTy = DBuilder.createSubroutineType(nullptr);
+ // Note: We use `FileScope` rather than `TheCU` as the scope because that's
+ // what LLVM's inliner seems to do.
+ SP = DBuilder.createFunction(
+ /*Scope=*/FileScope, /*Name=*/FakeFuncName, /*LinkageName=*/StringRef(),
+ /*File=*/FileScope, /*LineNo=*/0, /*Ty=*/DIFnTy,
+ /*ScopeLine=*/0,
+ /*Flags=*/llvm::DINode::FlagArtificial,
+ /*SPFlags=*/llvm::DISubprogram::SPFlagDefinition,
+ /*TParams=*/nullptr, /*ThrownTypes=*/nullptr, /*Annotations=*/nullptr);
+ }
+
+ return SP;
+}
+
void CGDebugInfo::CollectRecordLambdaFields(
const CXXRecordDecl *CXXDecl, SmallVectorImpl<llvm::Metadata *> &elements,
llvm::DIType *RecordTy) {
@@ -3427,6 +3448,27 @@ llvm::DIMacroFile *CGDebugInfo::CreateTempMacroFile(llvm::DIMacroFile *Parent,
return DBuilder.createTempMacroFile(Parent, Line, FName);
}
+llvm::DILocation *CGDebugInfo::CreateTrapFailureMessageFor(
+ llvm::DebugLoc TrapLocation, StringRef Prefix, StringRef FailureMsg) {
+ // Create debug info that describes a fake function whose name is the failure
+ // message.
+ std::string FuncName(Prefix);
+ if (!FailureMsg.empty()) {
+ // A space in the function name identifies this as not being a real function
+ // because it's not a valid symbol name.
+ FuncName += ": ";
+ FuncName += FailureMsg;
+ }
+
+ assert(FuncName.size() > 0);
+ assert(FuncName.find(' ') != std::string::npos &&
+ "Fake function name must contain a space");
+
+ llvm::DISubprogram *TrapSP = getFakeFuncSubprogram(FuncName);
+ return llvm::DILocation::get(CGM.getLLVMContext(), /*Line=*/0, /*Column=*/0,
+ /*Scope=*/TrapSP, /*InlinedAt=*/TrapLocation);
+}
+
static QualType UnwrapTypeForDebugInfo(QualType T, const ASTContext &C) {
Qualifiers Quals;
do {
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 7b60e94555d060..21edb553674260 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -346,6 +346,14 @@ class CGDebugInfo {
const FieldDecl *BitFieldDecl, const llvm::DIDerivedType *BitFieldDI,
llvm::ArrayRef<llvm::Metadata *> PreviousFieldsDI, const RecordDecl *RD);
+ // A cache that maps fake function names used for __builtin_verbose_trap to
+ // subprograms.
+ std::map<std::string, llvm::DISubprogram *> FakeFuncMap;
+
+ // A function that returns the subprogram corresponding to the fake function
+ // name.
+ llvm::DISubprogram *getFakeFuncSubprogram(const std::string &FakeFuncName);
+
/// Helpers for collecting fields of a record.
/// @{
void CollectRecordLambdaFields(const CXXRecordDecl *CXXDecl,
@@ -602,6 +610,18 @@ class CGDebugInfo {
return CoroutineParameterMappings;
}
+ // Create a debug location from `TrapLocation` that adds a fake
+ // inline frame where the frame name is
+ //
+ // * `<Prefix>: <FailureMsg>` if `<FailureMsg>` is not empty.
+ // * `<Prefix>` if `<FailureMsg>` is empty. Note `<Prefix>` must
+ // contain a space.
+ //
+ // This is used to store failure reasons for traps.
+ llvm::DILocation *CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
+ StringRef Prefix,
+ StringRef FailureMsg);
+
private:
/// Emit call to llvm.dbg.declare for a variable declaration.
/// Returns a pointer to the DILocalVariable associated with the
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 11401b6f56c0ea..32e4c5e0f19473 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -171,6 +171,23 @@ static bool checkArgCount(Sema &S, CallExpr *Call, unsigned DesiredArgCount) {
<< /*is non object*/ 0 << Call->getArg(1)->getSourceRange();
}
+static bool checkBuiltinVerboseTrap(CallExpr *Call, Sema &S) {
+ Expr *Arg = Call->getArg(0);
+
+ if (Arg->isValueDependent())
+ return true;
+
+ // FIXME: Add more checks and reject strings that can't be handled by
+ // debuggers.
+ std::string Result;
+ if (!Arg->tryEvaluateString(Result, S.Context) || Result.empty()) {
+ S.Diag(Arg->getBeginLoc(), diag::err_builtin_verbose_trap_arg)
+ << Arg->getSourceRange();
+ return false;
+ }
+ return true;
+}
+
static bool convertArgumentToType(Sema &S, Expr *&Value, QualType Ty) {
if (Value->isTypeDependent())
return false;
@@ -3205,6 +3222,11 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
case Builtin::BI__builtin_matrix_column_major_store:
return SemaBuiltinMatrixColumnMajorStore(TheCall, TheCallResult);
+ case Builtin::BI__builtin_verbose_trap:
+ if (!checkBuiltinVerboseTrap(TheCall, *this))
+ return ExprError();
+ break;
+
case Builtin::BI__builtin_get_device_side_mangled_name: {
auto Check = [](CallExpr *TheCall) {
if (TheCall->getNumArgs() != 1)
diff --git a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
new file mode 100644
index 00000000000000..04fa68ae93ecb6
--- /dev/null
+++ b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
@@ -0,0 +1,49 @@
+// RUN: %clang_cc1 -std=c++20 -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s
+
+// CHECK-LABEL: define void @_Z2f0v()
+// CHECK: call void @llvm.trap(), !dbg ![[LOC17:.*]]
+
+// CHECK-LABEL: define void @_Z2f1v()
+// CHECK: call void @llvm.trap(), !dbg ![[LOC23:.*]]
+// CHECK: call void @llvm.trap(), !dbg ![[LOC25:.*]]
+
+// CHECK-LABEL: define void @_Z2f3v()
+// CHECK: call void @_Z2f2IXadsoKcL_ZL8constMsgEEEEvv()
+
+// CHECK-LABEL: define internal void @_Z2f2IXadsoKcL_ZL8constMsgEEEEvv()
+// CHECK: call void @llvm.trap(), !dbg ![[LOC36:.*]]
+
+// CHECK: ![[FILESCOPE:.*]] = !DIFile(filename:
+// CHECK: ![[SUBPROG14:.*]] = distinct !DISubprogram(name: "f0", linkageName: "_Z2f0v",
+// CHECK: ![[LOC17]] = !DILocation(line: 0, scope: ![[SUBPROG18:.*]], inlinedAt: ![[LOC20:.*]])
+// CHECK: ![[SUBPROG18]] = distinct !DISubprogram(name: "__llvm_verbose_trap: Argument_must_not_be_null", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
+// CHECK: ![[LOC20]] = !DILocation(line: 34, column: 3, scope: ![[SUBPROG14]])
+// CHECK: ![[SUBPROG22:.*]] = distinct !DISubprogram(name: "f1", linkageName: "_Z2f1v",
+// CHECK: ![[LOC23]] = !DILocation(line: 0, scope: ![[SUBPROG18]], inlinedAt: ![[LOC24:.*]])
+// CHECK: ![[LOC24]] = !DILocation(line: 38, column: 3, scope: ![[SUBPROG22]])
+// CHECK: ![[LOC25]] = !DILocation(line: 0, scope: ![[SUBPROG26:.*]], inlinedAt: ![[LOC27:.*]])
+// CHECK: ![[SUBPROG26]] = distinct !DISubprogram(name: "__llvm_verbose_trap: hello", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
+// CHECK: ![[LOC27]] = !DILocation(line: 39, column: 3, scope: ![[SUBPROG22]])
+// CHECK: ![[SUBPROG32:.*]] = distinct !DISubprogram(name: "f2<&constMsg[0]>", linkageName: "_Z2f2IXadsoKcL_ZL8constMsgEEEEvv",
+// CHECK: ![[LOC36]] = !DILocation(line: 0, scope: ![[SUBPROG26]], inlinedAt: ![[LOC37:.*]])
+// CHECK: ![[LOC37]] = !DILocation(line: 44, column: 3, scope: ![[SUBPROG32]])
+
+char const constMsg[] = "hello";
+
+void f0() {
+ __builtin_verbose_trap("Argument_must_not_be_null");
+}
+
+void f1() {
+ __builtin_verbose_trap("Argument_must_not_be_null");
+ __builtin_verbose_trap("hello");
+}
+
+template <const char * const str>
+void f2() {
+ __builtin_verbose_trap(str);
+}
+
+void f3() {
+ f2<constMsg>();
+}
diff --git a/clang/test/SemaCXX/verbose-trap.cpp b/clang/test/SemaCXX/verbose-trap.cpp
new file mode 100644
index 00000000000000..7c152325d30815
--- /dev/null
+++ b/clang/test/SemaCXX/verbose-trap.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fcxx-exceptions -verify %s
+
+#if !__has_builtin(__builtin_verbose_trap)
+#error
+#endif
+
+constexpr char const* constMsg1 = "hello";
+char const* const constMsg2 = "hello";
+char const constMsg3[] = "hello";
+
+template <const char * const str>
+void f(const char * arg) {
+ __builtin_verbose_trap("Argument_must_not_be_null");
+ __builtin_verbose_trap("hello" "world");
+ __builtin_verbose_trap(constMsg1);
+ __builtin_verbose_trap(constMsg2);
+ __builtin_verbose_trap(""); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(); // expected-error {{too few arguments}}
+ __builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(1); // expected-error {{cannot initialize a parameter of type 'const char *' with}}
+ __builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(str);
+ __builtin_verbose_trap(u8"hello");
+}
+
+void test() {
+ f<constMsg3>(nullptr);
+}
>From c69b207ca52ac6524b6abb9c05770cb8e4cddbf8 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Tue, 23 Jan 2024 16:13:14 -0800
Subject: [PATCH 02/11] Fix diagnostic message
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 3 ++-
clang/test/SemaCXX/verbose-trap.cpp | 6 +++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 03f52c88ea1f1f..1cd1813f18d85f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8864,7 +8864,8 @@ def err_expected_callable_argument : Error<
def note_building_builtin_dump_struct_call : Note<
"in call to printing function with arguments '(%0)' while dumping struct">;
def err_builtin_verbose_trap_arg : Error<
- "argument to __builtin_verbose_trap must be a non-empty string literal">;
+ "argument to __builtin_verbose_trap must be a pointer to a non-empty constant "
+ "string">;
def err_atomic_load_store_uses_lib : Error<
"atomic %select{load|store}0 requires runtime support that is not "
diff --git a/clang/test/SemaCXX/verbose-trap.cpp b/clang/test/SemaCXX/verbose-trap.cpp
index 7c152325d30815..2cbfad6c817f82 100644
--- a/clang/test/SemaCXX/verbose-trap.cpp
+++ b/clang/test/SemaCXX/verbose-trap.cpp
@@ -14,11 +14,11 @@ void f(const char * arg) {
__builtin_verbose_trap("hello" "world");
__builtin_verbose_trap(constMsg1);
__builtin_verbose_trap(constMsg2);
- __builtin_verbose_trap(""); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(""); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
__builtin_verbose_trap(); // expected-error {{too few arguments}}
- __builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
__builtin_verbose_trap(1); // expected-error {{cannot initialize a parameter of type 'const char *' with}}
- __builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a non-empty string literal}}
+ __builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
__builtin_verbose_trap(str);
__builtin_verbose_trap(u8"hello");
}
>From 96f853b84ff524a0930efefe2c535d1a288ce1ea Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Thu, 25 Jan 2024 14:15:16 -0800
Subject: [PATCH 03/11] Address review comments
---
clang/docs/LanguageExtensions.rst | 19 +++++++++++--------
clang/lib/CodeGen/CGDebugInfo.cpp | 19 +++++++++----------
clang/lib/CodeGen/CGDebugInfo.h | 16 ++++++++--------
clang/test/SemaCXX/verbose-trap.cpp | 1 +
4 files changed, 29 insertions(+), 26 deletions(-)
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 4e4151e7803875..25d5f15e547368 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -3480,9 +3480,9 @@ debugger is attached or in a symbolicated crash log.
**Description**
``__builtin_verbose_trap`` is lowered to the ` ``llvm.trap`` <https://llvm.org/docs/LangRef.html#llvm-trap-intrinsic>`_ builtin.
-Additionally, clang emits debug metadata that represents an artificial inline
-frame whose name encodes the string passed to the builtin, prefixed by a "magic"
-prefix.
+Additionally, clang emits debugging information that represents an artificial
+inline frame whose name encodes the string passed to the builtin, prefixed by a
+"magic" prefix.
For example, consider the following code:
@@ -3490,27 +3490,30 @@ For example, consider the following code:
void foo(int* p) {
if (p == nullptr)
- __builtin_verbose_trap("Argument_must_not_be_null");
+ __builtin_verbose_trap("Argument must not be null!");
}
-The debug metadata would look as if it were produced for the following code:
+The debugging information would look as if it were produced for the following code:
.. code-block:: c++
__attribute__((always_inline))
- inline void "__llvm_verbose_trap: Argument_must_not_be_null"() {
+ inline void "__llvm_verbose_trap: Argument must not be null!"() {
__builtin_trap();
}
void foo(int* p) {
if (p == nullptr)
- "__llvm_verbose_trap: Argument_must_not_be_null"();
+ "__llvm_verbose_trap: Argument must not be null!"();
}
However, the LLVM IR would not actually contain a call to the artificial
function — it only exists in the debug metadata.
-Query for this feature with ``__has_builtin(__builtin_verbose_trap)``.
+Query for this feature with ``__has_builtin(__builtin_verbose_trap)``. Note that
+users need to enable debug information to enable this feature. A call to this
+builtin is equivalent to a call to ``__builtin_trap`` if debug information isn't
+enabled.
``__builtin_nondeterministic_value``
------------------------------------
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 81bb2854b80d3b..3fe91211d69795 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1632,8 +1632,8 @@ llvm::DIType *CGDebugInfo::createFieldType(
}
llvm::DISubprogram *
-CGDebugInfo::getFakeFuncSubprogram(const std::string &FakeFuncName) {
- llvm::DISubprogram *&SP = FakeFuncMap[FakeFuncName];
+CGDebugInfo::createInlinedTrapSubprogram(const std::string &FuncName) {
+ llvm::DISubprogram *&SP = InlinedTrapFuncMap[FuncName];
if (!SP) {
auto FileScope = TheCU->getFile();
@@ -1641,7 +1641,7 @@ CGDebugInfo::getFakeFuncSubprogram(const std::string &FakeFuncName) {
// Note: We use `FileScope` rather than `TheCU` as the scope because that's
// what LLVM's inliner seems to do.
SP = DBuilder.createFunction(
- /*Scope=*/FileScope, /*Name=*/FakeFuncName, /*LinkageName=*/StringRef(),
+ /*Scope=*/FileScope, /*Name=*/FuncName, /*LinkageName=*/StringRef(),
/*File=*/FileScope, /*LineNo=*/0, /*Ty=*/DIFnTy,
/*ScopeLine=*/0,
/*Flags=*/llvm::DINode::FlagArtificial,
@@ -3450,8 +3450,11 @@ llvm::DIMacroFile *CGDebugInfo::CreateTempMacroFile(llvm::DIMacroFile *Parent,
llvm::DILocation *CGDebugInfo::CreateTrapFailureMessageFor(
llvm::DebugLoc TrapLocation, StringRef Prefix, StringRef FailureMsg) {
- // Create debug info that describes a fake function whose name is the failure
- // message.
+ assert((!FailureMsg.empty() || Prefix.find(' ') != std::string::npos) &&
+ "Prefix must contain a space when FailureMsg is empty");
+
+ // Create debug info that describes an inlined function whose name is the
+ // failure message.
std::string FuncName(Prefix);
if (!FailureMsg.empty()) {
// A space in the function name identifies this as not being a real function
@@ -3460,11 +3463,7 @@ llvm::DILocation *CGDebugInfo::CreateTrapFailureMessageFor(
FuncName += FailureMsg;
}
- assert(FuncName.size() > 0);
- assert(FuncName.find(' ') != std::string::npos &&
- "Fake function name must contain a space");
-
- llvm::DISubprogram *TrapSP = getFakeFuncSubprogram(FuncName);
+ llvm::DISubprogram *TrapSP = createInlinedTrapSubprogram(FuncName);
return llvm::DILocation::get(CGM.getLLVMContext(), /*Line=*/0, /*Column=*/0,
/*Scope=*/TrapSP, /*InlinedAt=*/TrapLocation);
}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 21edb553674260..ff559153291836 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -346,13 +346,13 @@ class CGDebugInfo {
const FieldDecl *BitFieldDecl, const llvm::DIDerivedType *BitFieldDI,
llvm::ArrayRef<llvm::Metadata *> PreviousFieldsDI, const RecordDecl *RD);
- // A cache that maps fake function names used for __builtin_verbose_trap to
- // subprograms.
- std::map<std::string, llvm::DISubprogram *> FakeFuncMap;
+ // A cache that maps artificial inlined function names used for
+ // __builtin_verbose_trap to subprograms.
+ std::map<std::string, llvm::DISubprogram *> InlinedTrapFuncMap;
- // A function that returns the subprogram corresponding to the fake function
- // name.
- llvm::DISubprogram *getFakeFuncSubprogram(const std::string &FakeFuncName);
+ // A function that returns the subprogram corresponding to the artificial
+ // inlined function for traps.
+ llvm::DISubprogram *createInlinedTrapSubprogram(const std::string &FuncName);
/// Helpers for collecting fields of a record.
/// @{
@@ -610,8 +610,8 @@ class CGDebugInfo {
return CoroutineParameterMappings;
}
- // Create a debug location from `TrapLocation` that adds a fake
- // inline frame where the frame name is
+ // Create a debug location from `TrapLocation` that adds an artificial inline
+ // frame where the frame name is
//
// * `<Prefix>: <FailureMsg>` if `<FailureMsg>` is not empty.
// * `<Prefix>` if `<FailureMsg>` is empty. Note `<Prefix>` must
diff --git a/clang/test/SemaCXX/verbose-trap.cpp b/clang/test/SemaCXX/verbose-trap.cpp
index 2cbfad6c817f82..7968e999520957 100644
--- a/clang/test/SemaCXX/verbose-trap.cpp
+++ b/clang/test/SemaCXX/verbose-trap.cpp
@@ -10,6 +10,7 @@ char const constMsg3[] = "hello";
template <const char * const str>
void f(const char * arg) {
+ __builtin_verbose_trap("Arbitrary string literals can be used!");
__builtin_verbose_trap("Argument_must_not_be_null");
__builtin_verbose_trap("hello" "world");
__builtin_verbose_trap(constMsg1);
>From 499acc7f47fe2e353378d31017060f30184718df Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Mon, 29 Jan 2024 07:43:50 -0800
Subject: [PATCH 04/11] Address review comments
1. Test long string argument.
2. Test c++20 unicode.
3. Allow empty string arguments.
4. #inlcude <map> and <string>.
---
clang/include/clang/Basic/DiagnosticSemaKinds.td | 3 +--
clang/lib/CodeGen/CGDebugInfo.h | 2 ++
clang/lib/Sema/SemaChecking.cpp | 2 +-
clang/test/SemaCXX/verbose-trap.cpp | 12 +++++++++---
4 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index 1cd1813f18d85f..cefac72744f855 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8864,8 +8864,7 @@ def err_expected_callable_argument : Error<
def note_building_builtin_dump_struct_call : Note<
"in call to printing function with arguments '(%0)' while dumping struct">;
def err_builtin_verbose_trap_arg : Error<
- "argument to __builtin_verbose_trap must be a pointer to a non-empty constant "
- "string">;
+ "argument to __builtin_verbose_trap must be a pointer to a constant string">;
def err_atomic_load_store_uses_lib : Error<
"atomic %select{load|store}0 requires runtime support that is not "
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index ff559153291836..17a49a0fb990a9 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -29,7 +29,9 @@
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/Allocator.h"
+#include <map>
#include <optional>
+#include <string>
namespace llvm {
class MDNode;
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 32e4c5e0f19473..d906f7e7a1b3f2 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -180,7 +180,7 @@ static bool checkBuiltinVerboseTrap(CallExpr *Call, Sema &S) {
// FIXME: Add more checks and reject strings that can't be handled by
// debuggers.
std::string Result;
- if (!Arg->tryEvaluateString(Result, S.Context) || Result.empty()) {
+ if (!Arg->tryEvaluateString(Result, S.Context)) {
S.Diag(Arg->getBeginLoc(), diag::err_builtin_verbose_trap_arg)
<< Arg->getSourceRange();
return false;
diff --git a/clang/test/SemaCXX/verbose-trap.cpp b/clang/test/SemaCXX/verbose-trap.cpp
index 7968e999520957..e10529cc7c5480 100644
--- a/clang/test/SemaCXX/verbose-trap.cpp
+++ b/clang/test/SemaCXX/verbose-trap.cpp
@@ -1,4 +1,5 @@
// RUN: %clang_cc1 -std=c++11 -fsyntax-only -fcxx-exceptions -verify %s
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -fcxx-exceptions -verify %s
#if !__has_builtin(__builtin_verbose_trap)
#error
@@ -15,13 +16,18 @@ void f(const char * arg) {
__builtin_verbose_trap("hello" "world");
__builtin_verbose_trap(constMsg1);
__builtin_verbose_trap(constMsg2);
- __builtin_verbose_trap(""); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
+ __builtin_verbose_trap("");
__builtin_verbose_trap(); // expected-error {{too few arguments}}
- __builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
+ __builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a constant string}}
__builtin_verbose_trap(1); // expected-error {{cannot initialize a parameter of type 'const char *' with}}
- __builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a non-empty constant string}}
+ __builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a constant string}}
__builtin_verbose_trap(str);
__builtin_verbose_trap(u8"hello");
+#if __cplusplus >= 202002L
+ // FIXME: Accept c++20 u8 string literals.
+ // expected-error at -3 {{cannot initialize a parameter of type 'const char *' with an lvalue of type 'const char8_t[6]'}}
+#endif
+ __builtin_verbose_trap("abcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcdabcd");
}
void test() {
>From ac7293707afade4c7fe99aa3de8ee03639a6c3f3 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Mon, 29 Jan 2024 17:36:05 -0800
Subject: [PATCH 05/11] Add triple to test
---
clang/test/CodeGenCXX/debug-info-verbose-trap.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
index 04fa68ae93ecb6..54a21a96440001 100644
--- a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
+++ b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++20 -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s
+// RUN: %clang_cc1 -triple arm64-apple-ios -std=c++20 -emit-llvm -debug-info-kind=limited %s -o - | FileCheck %s
// CHECK-LABEL: define void @_Z2f0v()
// CHECK: call void @llvm.trap(), !dbg ![[LOC17:.*]]
>From 4788ae36b53114b0f78ddfae1f339d45a5fd0071 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Thu, 1 Feb 2024 08:43:34 -0800
Subject: [PATCH 06/11] Address review comments
---
clang/lib/CodeGen/CGBuiltin.cpp | 4 ++--
clang/lib/CodeGen/CGDebugInfo.cpp | 17 ++++++++---------
clang/lib/CodeGen/CGDebugInfo.h | 7 ++++---
3 files changed, 14 insertions(+), 14 deletions(-)
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index b9307331fc56c8..7598b7148e0e1e 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3579,8 +3579,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
if (getDebugInfo()) {
std::string Str;
E->getArg(0)->tryEvaluateString(Str, getContext());
- TrapLocation = getDebugInfo()->CreateTrapFailureMessageFor(
- TrapLocation, "__llvm_verbose_trap", Str);
+ TrapLocation =
+ getDebugInfo()->CreateTrapFailureMessageFor(TrapLocation, Str);
}
ApplyDebugLocation ApplyTrapDI(*this, TrapLocation);
EmitTrapCall(Intrinsic::trap);
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 3fe91211d69795..8d047fde086fdf 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1632,7 +1632,7 @@ llvm::DIType *CGDebugInfo::createFieldType(
}
llvm::DISubprogram *
-CGDebugInfo::createInlinedTrapSubprogram(const std::string &FuncName) {
+CGDebugInfo::createInlinedTrapSubprogram(StringRef FuncName) {
llvm::DISubprogram *&SP = InlinedTrapFuncMap[FuncName];
if (!SP) {
@@ -3448,14 +3448,13 @@ llvm::DIMacroFile *CGDebugInfo::CreateTempMacroFile(llvm::DIMacroFile *Parent,
return DBuilder.createTempMacroFile(Parent, Line, FName);
}
-llvm::DILocation *CGDebugInfo::CreateTrapFailureMessageFor(
- llvm::DebugLoc TrapLocation, StringRef Prefix, StringRef FailureMsg) {
- assert((!FailureMsg.empty() || Prefix.find(' ') != std::string::npos) &&
- "Prefix must contain a space when FailureMsg is empty");
-
- // Create debug info that describes an inlined function whose name is the
- // failure message.
- std::string FuncName(Prefix);
+llvm::DILocation *
+CGDebugInfo::CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
+ StringRef FailureMsg) {
+ // Create a debug location from `TrapLocation` that adds an artificial inline
+ // frame.
+ const char *Prefix = "__llvm_verbose_trap";
+ SmallString<64> FuncName(Prefix);
if (!FailureMsg.empty()) {
// A space in the function name identifies this as not being a real function
// because it's not a valid symbol name.
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 17a49a0fb990a9..e440b91b56a15b 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -350,11 +350,11 @@ class CGDebugInfo {
// A cache that maps artificial inlined function names used for
// __builtin_verbose_trap to subprograms.
- std::map<std::string, llvm::DISubprogram *> InlinedTrapFuncMap;
+ llvm::StringMap<llvm::DISubprogram *> InlinedTrapFuncMap;
// A function that returns the subprogram corresponding to the artificial
// inlined function for traps.
- llvm::DISubprogram *createInlinedTrapSubprogram(const std::string &FuncName);
+ llvm::DISubprogram *createInlinedTrapSubprogram(StringRef FuncName);
/// Helpers for collecting fields of a record.
/// @{
@@ -619,9 +619,10 @@ class CGDebugInfo {
// * `<Prefix>` if `<FailureMsg>` is empty. Note `<Prefix>` must
// contain a space.
//
+ // Currently `<Prefix>` is always "__llvm_verbose_trap".
+ //
// This is used to store failure reasons for traps.
llvm::DILocation *CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
- StringRef Prefix,
StringRef FailureMsg);
private:
>From 50ffca2cfc4c942435e14fc6e2b89845a7757140 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Thu, 1 Feb 2024 11:12:18 -0800
Subject: [PATCH 07/11] Pass a better file scope when creating the subprogram
for the artificial inlined function
`TheCU->getFile()` returns `<stdin>` when `-main-file-name` is empty.
---
clang/lib/CodeGen/CGDebugInfo.cpp | 9 ++++-----
clang/lib/CodeGen/CGDebugInfo.h | 3 ++-
clang/test/CodeGenCXX/debug-info-verbose-trap.cpp | 2 +-
3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 8d047fde086fdf..491033161bfed0 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1632,14 +1632,12 @@ llvm::DIType *CGDebugInfo::createFieldType(
}
llvm::DISubprogram *
-CGDebugInfo::createInlinedTrapSubprogram(StringRef FuncName) {
+CGDebugInfo::createInlinedTrapSubprogram(StringRef FuncName,
+ llvm::DIFile *FileScope) {
llvm::DISubprogram *&SP = InlinedTrapFuncMap[FuncName];
if (!SP) {
- auto FileScope = TheCU->getFile();
llvm::DISubroutineType *DIFnTy = DBuilder.createSubroutineType(nullptr);
- // Note: We use `FileScope` rather than `TheCU` as the scope because that's
- // what LLVM's inliner seems to do.
SP = DBuilder.createFunction(
/*Scope=*/FileScope, /*Name=*/FuncName, /*LinkageName=*/StringRef(),
/*File=*/FileScope, /*LineNo=*/0, /*Ty=*/DIFnTy,
@@ -3462,7 +3460,8 @@ CGDebugInfo::CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
FuncName += FailureMsg;
}
- llvm::DISubprogram *TrapSP = createInlinedTrapSubprogram(FuncName);
+ llvm::DISubprogram *TrapSP =
+ createInlinedTrapSubprogram(FuncName, TrapLocation->getFile());
return llvm::DILocation::get(CGM.getLLVMContext(), /*Line=*/0, /*Column=*/0,
/*Scope=*/TrapSP, /*InlinedAt=*/TrapLocation);
}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index e440b91b56a15b..2f1d907692ede0 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -354,7 +354,8 @@ class CGDebugInfo {
// A function that returns the subprogram corresponding to the artificial
// inlined function for traps.
- llvm::DISubprogram *createInlinedTrapSubprogram(StringRef FuncName);
+ llvm::DISubprogram *createInlinedTrapSubprogram(StringRef FuncName,
+ llvm::DIFile *FileScope);
/// Helpers for collecting fields of a record.
/// @{
diff --git a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
index 54a21a96440001..0b156c23a54a24 100644
--- a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
+++ b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
@@ -13,7 +13,7 @@
// CHECK-LABEL: define internal void @_Z2f2IXadsoKcL_ZL8constMsgEEEEvv()
// CHECK: call void @llvm.trap(), !dbg ![[LOC36:.*]]
-// CHECK: ![[FILESCOPE:.*]] = !DIFile(filename:
+// CHECK: ![[FILESCOPE:.*]] = !DIFile(filename: "{{.*}}debug-info-verbose-trap.cpp"
// CHECK: ![[SUBPROG14:.*]] = distinct !DISubprogram(name: "f0", linkageName: "_Z2f0v",
// CHECK: ![[LOC17]] = !DILocation(line: 0, scope: ![[SUBPROG18:.*]], inlinedAt: ![[LOC20:.*]])
// CHECK: ![[SUBPROG18]] = distinct !DISubprogram(name: "__llvm_verbose_trap: Argument_must_not_be_null", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
>From 4224667fcc3ea1425c4c85ea8d56505649918b84 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Mon, 4 Mar 2024 21:31:49 -0800
Subject: [PATCH 08/11] Address review comments
---
clang/docs/LanguageExtensions.rst | 3 ++
clang/include/clang/AST/Expr.h | 6 ++--
clang/lib/AST/ExprConstant.cpp | 7 +++--
clang/lib/CodeGen/CGBuiltin.cpp | 6 ++--
clang/lib/CodeGen/CGDebugInfo.cpp | 5 ++--
clang/lib/CodeGen/CGDebugInfo.h | 3 +-
clang/lib/Sema/SemaChecking.cpp | 3 +-
.../CodeGenCXX/debug-info-verbose-trap.cpp | 30 +++++++++++--------
clang/test/SemaCXX/verbose-trap.cpp | 2 +-
9 files changed, 36 insertions(+), 29 deletions(-)
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 25d5f15e547368..cbed60aba6c58c 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -3515,6 +3515,9 @@ users need to enable debug information to enable this feature. A call to this
builtin is equivalent to a call to ``__builtin_trap`` if debug information isn't
enabled.
+The optimizer can merge calls to trap with different messages, which degrades
+the debugging experience.
+
``__builtin_nondeterministic_value``
------------------------------------
diff --git a/clang/include/clang/AST/Expr.h b/clang/include/clang/AST/Expr.h
index 789bedbd9724a6..78441f6edb315b 100644
--- a/clang/include/clang/AST/Expr.h
+++ b/clang/include/clang/AST/Expr.h
@@ -788,9 +788,9 @@ class Expr : public ValueStmt {
EvalResult &Status) const;
/// If the current Expr can be evaluated to a pointer to a null-terminated
- /// constant string, return the constant string (without the terminating null)
- /// in Result. Return true if it succeeds.
- bool tryEvaluateString(std::string &Result, ASTContext &Ctx) const;
+ /// constant string, return the constant string (without the terminating
+ /// null).
+ std::optional<std::string> tryEvaluateString(ASTContext &Ctx) const;
/// Enumeration used to describe the kind of Null pointer constant
/// returned from \c isNullPointerConstant().
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 127c0415f8feb8..d020903312b85b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -16841,12 +16841,15 @@ static bool EvaluateBuiltinStrLen(const Expr *E, uint64_t &Result,
}
}
-bool Expr::tryEvaluateString(std::string &StringResult, ASTContext &Ctx) const {
+std::optional<std::string> Expr::tryEvaluateString(ASTContext &Ctx) const {
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
uint64_t Result;
+ std::string StringResult;
- return EvaluateBuiltinStrLen(this, Result, Info, &StringResult);
+ if (EvaluateBuiltinStrLen(this, Result, Info, &StringResult))
+ return StringResult;
+ return {};
}
bool Expr::EvaluateCharRangeAsString(std::string &Result,
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 7598b7148e0e1e..a95275e2861d9d 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3577,10 +3577,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
case Builtin::BI__builtin_verbose_trap: {
llvm::DILocation *TrapLocation = Builder.getCurrentDebugLocation();
if (getDebugInfo()) {
- std::string Str;
- E->getArg(0)->tryEvaluateString(Str, getContext());
- TrapLocation =
- getDebugInfo()->CreateTrapFailureMessageFor(TrapLocation, Str);
+ TrapLocation = getDebugInfo()->CreateTrapFailureMessageFor(
+ TrapLocation, *E->getArg(0)->tryEvaluateString(getContext()));
}
ApplyDebugLocation ApplyTrapDI(*this, TrapLocation);
EmitTrapCall(Intrinsic::trap);
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 491033161bfed0..48980354fa0bcd 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -1634,6 +1634,9 @@ llvm::DIType *CGDebugInfo::createFieldType(
llvm::DISubprogram *
CGDebugInfo::createInlinedTrapSubprogram(StringRef FuncName,
llvm::DIFile *FileScope) {
+ // We are caching the subprogram because we don't want to duplicate
+ // subprograms with the same message. Note that `SPFlagDefinition` prevents
+ // subprograms from being uniqued.
llvm::DISubprogram *&SP = InlinedTrapFuncMap[FuncName];
if (!SP) {
@@ -3454,8 +3457,6 @@ CGDebugInfo::CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
const char *Prefix = "__llvm_verbose_trap";
SmallString<64> FuncName(Prefix);
if (!FailureMsg.empty()) {
- // A space in the function name identifies this as not being a real function
- // because it's not a valid symbol name.
FuncName += ": ";
FuncName += FailureMsg;
}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 2f1d907692ede0..4aef93f76520ed 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -617,8 +617,7 @@ class CGDebugInfo {
// frame where the frame name is
//
// * `<Prefix>: <FailureMsg>` if `<FailureMsg>` is not empty.
- // * `<Prefix>` if `<FailureMsg>` is empty. Note `<Prefix>` must
- // contain a space.
+ // * `<Prefix>` if `<FailureMsg>` is empty.
//
// Currently `<Prefix>` is always "__llvm_verbose_trap".
//
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index d906f7e7a1b3f2..05958e660e041a 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -179,8 +179,7 @@ static bool checkBuiltinVerboseTrap(CallExpr *Call, Sema &S) {
// FIXME: Add more checks and reject strings that can't be handled by
// debuggers.
- std::string Result;
- if (!Arg->tryEvaluateString(Result, S.Context)) {
+ if (!Arg->tryEvaluateString(S.Context).has_value()) {
S.Diag(Arg->getBeginLoc(), diag::err_builtin_verbose_trap_arg)
<< Arg->getSourceRange();
return false;
diff --git a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
index 0b156c23a54a24..0854b76a4bdea4 100644
--- a/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
+++ b/clang/test/CodeGenCXX/debug-info-verbose-trap.cpp
@@ -3,6 +3,8 @@
// CHECK-LABEL: define void @_Z2f0v()
// CHECK: call void @llvm.trap(), !dbg ![[LOC17:.*]]
+// CHECK: declare void @llvm.trap() #[[ATTR1:.*]]
+
// CHECK-LABEL: define void @_Z2f1v()
// CHECK: call void @llvm.trap(), !dbg ![[LOC23:.*]]
// CHECK: call void @llvm.trap(), !dbg ![[LOC25:.*]]
@@ -13,32 +15,34 @@
// CHECK-LABEL: define internal void @_Z2f2IXadsoKcL_ZL8constMsgEEEEvv()
// CHECK: call void @llvm.trap(), !dbg ![[LOC36:.*]]
+// CHECK: attributes #[[ATTR1]] = { cold {{.*}}}
+
// CHECK: ![[FILESCOPE:.*]] = !DIFile(filename: "{{.*}}debug-info-verbose-trap.cpp"
-// CHECK: ![[SUBPROG14:.*]] = distinct !DISubprogram(name: "f0", linkageName: "_Z2f0v",
-// CHECK: ![[LOC17]] = !DILocation(line: 0, scope: ![[SUBPROG18:.*]], inlinedAt: ![[LOC20:.*]])
-// CHECK: ![[SUBPROG18]] = distinct !DISubprogram(name: "__llvm_verbose_trap: Argument_must_not_be_null", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
-// CHECK: ![[LOC20]] = !DILocation(line: 34, column: 3, scope: ![[SUBPROG14]])
-// CHECK: ![[SUBPROG22:.*]] = distinct !DISubprogram(name: "f1", linkageName: "_Z2f1v",
-// CHECK: ![[LOC23]] = !DILocation(line: 0, scope: ![[SUBPROG18]], inlinedAt: ![[LOC24:.*]])
-// CHECK: ![[LOC24]] = !DILocation(line: 38, column: 3, scope: ![[SUBPROG22]])
-// CHECK: ![[LOC25]] = !DILocation(line: 0, scope: ![[SUBPROG26:.*]], inlinedAt: ![[LOC27:.*]])
-// CHECK: ![[SUBPROG26]] = distinct !DISubprogram(name: "__llvm_verbose_trap: hello", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
-// CHECK: ![[LOC27]] = !DILocation(line: 39, column: 3, scope: ![[SUBPROG22]])
-// CHECK: ![[SUBPROG32:.*]] = distinct !DISubprogram(name: "f2<&constMsg[0]>", linkageName: "_Z2f2IXadsoKcL_ZL8constMsgEEEEvv",
-// CHECK: ![[LOC36]] = !DILocation(line: 0, scope: ![[SUBPROG26]], inlinedAt: ![[LOC37:.*]])
-// CHECK: ![[LOC37]] = !DILocation(line: 44, column: 3, scope: ![[SUBPROG32]])
char const constMsg[] = "hello";
+// CHECK: ![[SUBPROG14:.*]] = distinct !DISubprogram(name: "f0", linkageName: "_Z2f0v",
+// CHECK: ![[LOC17]] = !DILocation(line: 0, scope: ![[SUBPROG18:.*]], inlinedAt: ![[LOC20:.*]])
+// CHECK: ![[SUBPROG18]] = distinct !DISubprogram(name: "__llvm_verbose_trap: Argument_must_not_be_null", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
+// CHECK: ![[LOC20]] = !DILocation(line: [[@LINE+2]], column: 3, scope: ![[SUBPROG14]])
void f0() {
__builtin_verbose_trap("Argument_must_not_be_null");
}
+// CHECK: ![[SUBPROG22:.*]] = distinct !DISubprogram(name: "f1", linkageName: "_Z2f1v",
+// CHECK: ![[LOC23]] = !DILocation(line: 0, scope: ![[SUBPROG18]], inlinedAt: ![[LOC24:.*]])
+// CHECK: ![[LOC24]] = !DILocation(line: [[@LINE+5]], column: 3, scope: ![[SUBPROG22]])
+// CHECK: ![[LOC25]] = !DILocation(line: 0, scope: ![[SUBPROG26:.*]], inlinedAt: ![[LOC27:.*]])
+// CHECK: ![[SUBPROG26]] = distinct !DISubprogram(name: "__llvm_verbose_trap: hello", scope: ![[FILESCOPE]], file: ![[FILESCOPE]], type: !{{.*}}, flags: DIFlagArtificial, spFlags: DISPFlagDefinition, unit: !{{.*}})
+// CHECK: ![[LOC27]] = !DILocation(line: [[@LINE+3]], column: 3, scope: ![[SUBPROG22]])
void f1() {
__builtin_verbose_trap("Argument_must_not_be_null");
__builtin_verbose_trap("hello");
}
+// CHECK: ![[SUBPROG32:.*]] = distinct !DISubprogram(name: "f2<&constMsg[0]>", linkageName: "_Z2f2IXadsoKcL_ZL8constMsgEEEEvv",
+// CHECK: ![[LOC36]] = !DILocation(line: 0, scope: ![[SUBPROG26]], inlinedAt: ![[LOC37:.*]])
+// CHECK: ![[LOC37]] = !DILocation(line: [[@LINE+3]], column: 3, scope: ![[SUBPROG32]])
template <const char * const str>
void f2() {
__builtin_verbose_trap(str);
diff --git a/clang/test/SemaCXX/verbose-trap.cpp b/clang/test/SemaCXX/verbose-trap.cpp
index e10529cc7c5480..86458a3957e7fc 100644
--- a/clang/test/SemaCXX/verbose-trap.cpp
+++ b/clang/test/SemaCXX/verbose-trap.cpp
@@ -19,7 +19,7 @@ void f(const char * arg) {
__builtin_verbose_trap("");
__builtin_verbose_trap(); // expected-error {{too few arguments}}
__builtin_verbose_trap(0); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a constant string}}
- __builtin_verbose_trap(1); // expected-error {{cannot initialize a parameter of type 'const char *' with}}
+ __builtin_verbose_trap(1); // expected-error {{cannot initialize a parameter of type 'const char *' with an rvalue of type 'int'}}
__builtin_verbose_trap(arg); // expected-error {{argument to __builtin_verbose_trap must be a pointer to a constant string}}
__builtin_verbose_trap(str);
__builtin_verbose_trap(u8"hello");
>From 1389cc8fd583fe48587c5bf091e1f900bdda98bb Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Tue, 12 Mar 2024 16:58:23 -0700
Subject: [PATCH 09/11] Define CLANG_VERBOSE_TRAP_PREFIX in public header
---
clang/include/clang/CodeGen/ModuleBuilder.h | 3 +++
clang/lib/CodeGen/CGDebugInfo.cpp | 3 ++-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/clang/include/clang/CodeGen/ModuleBuilder.h b/clang/include/clang/CodeGen/ModuleBuilder.h
index edacd82bf899db..69f4537330ba57 100644
--- a/clang/include/clang/CodeGen/ModuleBuilder.h
+++ b/clang/include/clang/CodeGen/ModuleBuilder.h
@@ -27,6 +27,9 @@ namespace llvm {
}
}
+// Prefix for __builtin_verbose_trap.
+#define CLANG_VERBOSE_TRAP_PREFIX "__llvm_verbose_trap"
+
namespace clang {
class CodeGenOptions;
class CoverageSourceInfo;
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index 48980354fa0bcd..cc07b7b697bbd7 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -32,6 +32,7 @@
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/Version.h"
+#include "clang/CodeGen/ModuleBuilder.h"
#include "clang/Frontend/FrontendOptions.h"
#include "clang/Lex/HeaderSearchOptions.h"
#include "clang/Lex/ModuleMap.h"
@@ -3454,7 +3455,7 @@ CGDebugInfo::CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
StringRef FailureMsg) {
// Create a debug location from `TrapLocation` that adds an artificial inline
// frame.
- const char *Prefix = "__llvm_verbose_trap";
+ const char *Prefix = CLANG_VERBOSE_TRAP_PREFIX;
SmallString<64> FuncName(Prefix);
if (!FailureMsg.empty()) {
FuncName += ": ";
>From f4a38e0543731b8a217b76bc3c6d0bc578d7606b Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Tue, 19 Mar 2024 18:56:37 -0700
Subject: [PATCH 10/11] Address review comments
---
clang/docs/LanguageExtensions.rst | 4 ++--
clang/lib/CodeGen/CGBuiltin.cpp | 1 +
clang/lib/CodeGen/CGDebugInfo.h | 22 +++++++++++-----------
3 files changed, 14 insertions(+), 13 deletions(-)
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index cbed60aba6c58c..8bfc859466d93e 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -3507,8 +3507,8 @@ The debugging information would look as if it were produced for the following co
"__llvm_verbose_trap: Argument must not be null!"();
}
-However, the LLVM IR would not actually contain a call to the artificial
-function — it only exists in the debug metadata.
+However, the generated code would not actually contain a call to the artificial
+function — it only exists in the debugging information.
Query for this feature with ``__has_builtin(__builtin_verbose_trap)``. Note that
users need to enable debug information to enable this feature. A call to this
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index a95275e2861d9d..0a7da917b5d626 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3581,6 +3581,7 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
TrapLocation, *E->getArg(0)->tryEvaluateString(getContext()));
}
ApplyDebugLocation ApplyTrapDI(*this, TrapLocation);
+ // Currently no attempt is made to prevent traps from being merged.
EmitTrapCall(Intrinsic::trap);
return RValue::get(nullptr);
}
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 4aef93f76520ed..857a4711db16b9 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -348,8 +348,8 @@ class CGDebugInfo {
const FieldDecl *BitFieldDecl, const llvm::DIDerivedType *BitFieldDI,
llvm::ArrayRef<llvm::Metadata *> PreviousFieldsDI, const RecordDecl *RD);
- // A cache that maps artificial inlined function names used for
- // __builtin_verbose_trap to subprograms.
+ /// A cache that maps artificial inlined function names used for
+ /// __builtin_verbose_trap to subprograms.
llvm::StringMap<llvm::DISubprogram *> InlinedTrapFuncMap;
// A function that returns the subprogram corresponding to the artificial
@@ -613,15 +613,15 @@ class CGDebugInfo {
return CoroutineParameterMappings;
}
- // Create a debug location from `TrapLocation` that adds an artificial inline
- // frame where the frame name is
- //
- // * `<Prefix>: <FailureMsg>` if `<FailureMsg>` is not empty.
- // * `<Prefix>` if `<FailureMsg>` is empty.
- //
- // Currently `<Prefix>` is always "__llvm_verbose_trap".
- //
- // This is used to store failure reasons for traps.
+ /// Create a debug location from `TrapLocation` that adds an artificial inline
+ /// frame where the frame name is
+ ///
+ /// * `<Prefix>: <FailureMsg>` if `<FailureMsg>` is not empty.
+ /// * `<Prefix>` if `<FailureMsg>` is empty.
+ ///
+ /// Currently `<Prefix>` is always "__llvm_verbose_trap".
+ ///
+ /// This is used to store failure reasons for traps.
llvm::DILocation *CreateTrapFailureMessageFor(llvm::DebugLoc TrapLocation,
StringRef FailureMsg);
>From faf771a9a33efdead7023a92c9ada9a7134398eb Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Wed, 20 Mar 2024 12:38:22 -0700
Subject: [PATCH 11/11] Use three forward slashes
---
clang/lib/CodeGen/CGDebugInfo.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
index 857a4711db16b9..643cafae1db45a 100644
--- a/clang/lib/CodeGen/CGDebugInfo.h
+++ b/clang/lib/CodeGen/CGDebugInfo.h
@@ -352,8 +352,8 @@ class CGDebugInfo {
/// __builtin_verbose_trap to subprograms.
llvm::StringMap<llvm::DISubprogram *> InlinedTrapFuncMap;
- // A function that returns the subprogram corresponding to the artificial
- // inlined function for traps.
+ /// A function that returns the subprogram corresponding to the artificial
+ /// inlined function for traps.
llvm::DISubprogram *createInlinedTrapSubprogram(StringRef FuncName,
llvm::DIFile *FileScope);
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