[llvm-branch-commits] [clang] [KeyInstr][Clang] Scalar init atom (PR #134633)

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

https://github.com/OCHyams created https://github.com/llvm/llvm-project/pull/134633

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 29d5428307acc1493f2bb2819b627688b4917c07 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Tue, 1 Apr 2025 14:50:41 +0100
Subject: [PATCH] [KeyInstr][Clang] Scalar 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             |  1 +
 clang/lib/CodeGen/CGExpr.cpp             |  2 ++
 clang/test/KeyInstructions/init-scalar.c | 19 +++++++++++++++++++
 3 files changed, 22 insertions(+)
 create mode 100644 clang/test/KeyInstructions/init-scalar.c

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index eab1ebfb2369b..96d217b0a13cc 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1921,6 +1921,7 @@ void CodeGenFunction::EmitAutoVarInit(const AutoVarEmission &emission) {
 
   const VarDecl &D = *emission.Variable;
   auto DL = ApplyDebugLocation::CreateDefaultArtificial(*this, D.getLocation());
+  ApplyAtomGroup Grp(getDebugInfo());
   QualType type = D.getType();
 
   // If this local has an initializer, emit it now.
diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 5943ff9294e1a..a00a8ba2cd5cb 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2180,6 +2180,8 @@ void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, Address Addr,
   }
 
   llvm::StoreInst *Store = Builder.CreateStore(Value, Addr, Volatile);
+  addInstToCurrentSourceAtom(Store, Value);
+
   if (isNontemporal) {
     llvm::MDNode *Node =
         llvm::MDNode::get(Store->getContext(),
diff --git a/clang/test/KeyInstructions/init-scalar.c b/clang/test/KeyInstructions/init-scalar.c
new file mode 100644
index 0000000000000..c212c2a4fd623
--- /dev/null
+++ b/clang/test/KeyInstructions/init-scalar.c
@@ -0,0 +1,19 @@
+// RUN: %clang -gkey-instructions -x c++ %s -gmlt -gcolumn-info -S -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -x c %s -gmlt -gcolumn-info -S -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+void a() {
+// CHECK: store i32 0, ptr %A{{.*}}, !dbg [[G1R1:!.*]]
+    int A = 0;
+// CHECK: %add = add {{.*}}, !dbg [[G2R2:!.*]]
+// CHECK: store i32 %add, ptr %B, align 4, !dbg [[G2R1:!.*]]
+    int B = 2 * A + 1;
+// CHECK-TODO: ret{{.*}}, !dbg [[G3R1:!.*]]
+}
+
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R2]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+// CHECK-TODO: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)