[llvm-branch-commits] [clang] [KeyInstr][Clang] Static variable init atom (PR #134636)

[Orlando Cazalet-Hyams via llvm-branch-commits]

https://github.com/OCHyams created https://github.com/llvm/llvm-project/pull/134636

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

>From a92afbf589152ebb3f98802a81186792d3e911ee Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Wed, 2 Apr 2025 17:42:48 +0100
Subject: [PATCH] [KeyInstr][Clang] Static 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/CGDecl.cpp               |  4 +++-
 clang/test/KeyInstructions/init-static.cpp | 12 ++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/KeyInstructions/init-static.cpp

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 9860ab0b033bb..3c5597a00f2ea 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -428,8 +428,10 @@ void CodeGenFunction::EmitStaticVarDecl(const VarDecl &D,
   bool isCudaSharedVar = getLangOpts().CUDA && getLangOpts().CUDAIsDevice &&
                          D.hasAttr<CUDASharedAttr>();
   // If this value has an initializer, emit it.
-  if (D.getInit() && !isCudaSharedVar)
+  if (D.getInit() && !isCudaSharedVar) {
+    ApplyAtomGroup Grp(getDebugInfo());
     var = AddInitializerToStaticVarDecl(D, var);
+  }
 
   var->setAlignment(alignment.getAsAlign());
 
diff --git a/clang/test/KeyInstructions/init-static.cpp b/clang/test/KeyInstructions/init-static.cpp
new file mode 100644
index 0000000000000..82e14b59df5e5
--- /dev/null
+++ b/clang/test/KeyInstructions/init-static.cpp
@@ -0,0 +1,12 @@
+// RUN: %clang -gkey-instructions %s -gmlt -gcolumn-info -S -emit-llvm -o -\
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+void g(int *a) {
+    // CHECK: %2 = load ptr, ptr %a.addr{{.*}}, !dbg [[G1R2:!.*]]
+    // CHECK: store ptr %2, ptr @_ZZ1gPiE1b{{.*}}, !dbg [[G1R1:!.*]]
+    static int &b = *a;
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+