Add support for __builtin_verbose_trap (#79230)

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's CodeGen lowers the builtin to `llvm.trap` and emits debugging
information that represents an artificial inline frame whose name
encodes the category and reason strings passed to the builtin.

1 files changed, 40 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index a072475..3d8a715 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"
@@ -1731,6 +1732,28 @@ llvm::DIType *CGDebugInfo::createFieldType(
                                    offsetInBits, flags, debugType, Annotations);
 }
 
+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) {
+    llvm::DISubroutineType *DIFnTy = DBuilder.createSubroutineType(nullptr);
+    SP = DBuilder.createFunction(
+        /*Scope=*/FileScope, /*Name=*/FuncName, /*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) {
@@ -3527,6 +3550,23 @@ llvm::DIMacroFile *CGDebugInfo::CreateTempMacroFile(llvm::DIMacroFile *Parent,
   return DBuilder.createTempMacroFile(Parent, Line, FName);
 }
 
+llvm::DILocation *CGDebugInfo::CreateTrapFailureMessageFor(
+    llvm::DebugLoc TrapLocation, StringRef Category, StringRef FailureMsg) {
+  // Create a debug location from `TrapLocation` that adds an artificial inline
+  // frame.
+  SmallString<64> FuncName(ClangTrapPrefix);
+
+  FuncName += "$";
+  FuncName += Category;
+  FuncName += "$";
+  FuncName += FailureMsg;
+
+  llvm::DISubprogram *TrapSP =
+      createInlinedTrapSubprogram(FuncName, TrapLocation->getFile());
+  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 {