[clang] [KeyInstr][Clang] Reset atomGroup number for each function (PR #141607)

[Orlando Cazalet-Hyams via cfe-commits]

https://github.com/OCHyams created https://github.com/llvm/llvm-project/pull/141607

CGDebugInfo::completeFunction was added previously but mistakenly not called (dropped through the cracks while putting together the patch stack). Moved out of #134652 and #134654.

>From 510cb679b679f7265107127cc3d57a76b576e42d Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Tue, 27 May 2025 14:57:12 +0100
Subject: [PATCH] [KeyInstr][Clang] Reset atomGroup number for each function

CGDebugInfo::completeFunction was added previously but mistakenly
not called (dropped through the cracks while putting together
the patch stack). Moved out of #134652 and #134654.
---
 clang/lib/CodeGen/CodeGenFunction.cpp         |  6 ++++++
 .../DebugInfo/KeyInstructions/multi-func.c    | 19 +++++++++++++++++++
 2 files changed, 25 insertions(+)
 create mode 100644 clang/test/DebugInfo/KeyInstructions/multi-func.c

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 0356952f4f291..a9ef2784c2fb6 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -36,6 +36,7 @@
 #include "clang/CodeGen/CGFunctionInfo.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/Frontend/OpenMP/OMPIRBuilder.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
@@ -1506,6 +1507,11 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
     // Disable debug info indefinitely for this function
     DebugInfo = nullptr;
   }
+  // Finalize function debug info on exit.
+  auto Cleanup = llvm::make_scope_exit([this] {
+    if (CGDebugInfo *DI = getDebugInfo())
+      DI->completeFunction();
+  });
 
   // The function might not have a body if we're generating thunks for a
   // function declaration.
diff --git a/clang/test/DebugInfo/KeyInstructions/multi-func.c b/clang/test/DebugInfo/KeyInstructions/multi-func.c
new file mode 100644
index 0000000000000..6e225eed81de8
--- /dev/null
+++ b/clang/test/DebugInfo/KeyInstructions/multi-func.c
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -gkey-instructions -gno-column-info -x c++ %s -debug-info-kind=line-tables-only -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -gkey-instructions -gno-column-info -x c %s -debug-info-kind=line-tables-only -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// Check atomGroup is reset to start at 1 in each function.
+
+int g;
+// CHECK: store{{.*}}, !dbg [[AG:!.*]]
+void a() { g = 0; }
+
+// CHECK: store{{.*}}, !dbg [[BG:!.*]]
+void b() { g = 0; }
+
+// CHECK: [[A:!.*]] = distinct !DISubprogram(name: "a",
+// CHECK: [[AG]] = !DILocation(line: 11, scope: [[A]], atomGroup: 1, atomRank: 1)
+// CHECK: [[B:!.*]] = distinct !DISubprogram(name: "b",
+// CHECK: [[BG]] = !DILocation(line: 14, scope: [[B]], atomGroup: 1, atomRank: 1)