[clang] [KeyInstr][Clang] Catch variable init atom (PR #134641)

[Orlando Cazalet-Hyams via cfe-commits]

https://github.com/OCHyams updated https://github.com/llvm/llvm-project/pull/134641

>From 7c86cc1b0b0bfaba4c304a31b5b0f2a1f391ad63 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Thu, 3 Apr 2025 17:31:32 +0100
Subject: [PATCH 1/3] [KeyInstr][Clang] Catch variable init atom

This patch is part of a stack that teaches Clang to generate Key Instructions
metadata for C and C++.

The Key Instructions project is introduced, including a "quick summary" section
at the top which adds context for this PR, here:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668

The feature is only functional in LLVM if LLVM is built with CMake flag
LLVM_EXPERIMENTAL_KEY_INSTRUCTIONs. Eventually that flag will be removed.

The Clang-side work is demoed here:
https://github.com/llvm/llvm-project/pull/130943
---
 clang/lib/CodeGen/ItaniumCXXABI.cpp           |  1 +
 .../DebugInfo/KeyInstructions/try-catch.cpp   | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 clang/test/DebugInfo/KeyInstructions/try-catch.cpp

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index faa07024a6052..1041ae84dbdf1 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -5055,6 +5055,7 @@ void ItaniumCXXABI::emitBeginCatch(CodeGenFunction &CGF,
 
   // Emit the local.
   CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
+  ApplyAtomGroup Grp(CGF.getDebugInfo());
   InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF), S->getBeginLoc());
   CGF.EmitAutoVarCleanups(var);
 }
diff --git a/clang/test/DebugInfo/KeyInstructions/try-catch.cpp b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
new file mode 100644
index 0000000000000..3d1080aca2f07
--- /dev/null
+++ b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang -gkey-instructions %s -gmlt -S -emit-llvm -o - -fexceptions \
+// RUN: | FileCheck %s
+
+void except() {
+  // FIXME(OCH): Should `store i32 32, ptr %exception` be key?
+  throw 32;
+}
+
+void attempt() {
+  try { except(); }
+// CHECK: catch:
+// CHECK: %4 = call ptr @__cxa_begin_catch(ptr %exn)
+// CHECK: %5 = load i32{{.*}}, !dbg [[G1R2:!.*]]
+// CHECK: store i32 %5, ptr %e{{.*}}, !dbg [[G1R1:!.*]]
+// CHECK: call void @__cxa_end_catch()
+  catch (int e) { }
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)

>From 5d308ddf70afa9e7ec8382c0abada43f4296a486 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Wed, 21 May 2025 15:30:39 +0100
Subject: [PATCH 2/3] cc1

---
 clang/test/DebugInfo/KeyInstructions/try-catch.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/test/DebugInfo/KeyInstructions/try-catch.cpp b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
index 3d1080aca2f07..d2b458f361e11 100644
--- a/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
+++ b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang -gkey-instructions %s -gmlt -S -emit-llvm -o - -fexceptions \
+// RUN: %clang_cc1 -gkey-instructions %s -debug-info-kind=line-tables-only -emit-llvm -o - -fexceptions -fcxx-exceptions \
 // RUN: | FileCheck %s
 
 void except() {

>From a2b11b1914d80d0796747b6f1045719893e2194f Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Tue, 27 May 2025 11:11:22 +0100
Subject: [PATCH 3/3] braces + add triple to test

---
 clang/lib/CodeGen/ItaniumCXXABI.cpp                | 7 +++++--
 clang/test/DebugInfo/KeyInstructions/try-catch.cpp | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp
index 1041ae84dbdf1..5018a6b39b000 100644
--- a/clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -5055,8 +5055,11 @@ void ItaniumCXXABI::emitBeginCatch(CodeGenFunction &CGF,
 
   // Emit the local.
   CodeGenFunction::AutoVarEmission var = CGF.EmitAutoVarAlloca(*CatchParam);
-  ApplyAtomGroup Grp(CGF.getDebugInfo());
-  InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF), S->getBeginLoc());
+  {
+    ApplyAtomGroup Grp(CGF.getDebugInfo());
+    InitCatchParam(CGF, *CatchParam, var.getObjectAddress(CGF),
+                   S->getBeginLoc());
+  }
   CGF.EmitAutoVarCleanups(var);
 }
 
diff --git a/clang/test/DebugInfo/KeyInstructions/try-catch.cpp b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
index d2b458f361e11..918eb4c97db9a 100644
--- a/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
+++ b/clang/test/DebugInfo/KeyInstructions/try-catch.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -gkey-instructions %s -debug-info-kind=line-tables-only -emit-llvm -o - -fexceptions -fcxx-exceptions \
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -gkey-instructions %s -debug-info-kind=line-tables-only -emit-llvm -o - -fexceptions -fcxx-exceptions \
 // RUN: | FileCheck %s
 
 void except() {