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

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

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

>From 8534d6e34772867640665bfa3ad3547babd1a12d 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 1/2] [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 ++
 .../DebugInfo/KeyInstructions/init-scalar.c   | 19 +++++++++++++++++++
 3 files changed, 22 insertions(+)
 create mode 100644 clang/test/DebugInfo/KeyInstructions/init-scalar.c

diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index 4a8f7f6a42ecb..d02f2ad09d2f1 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -1925,6 +1925,7 @@ 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 708002a7f9ab3..1e426586620a2 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2222,6 +2222,8 @@ 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/DebugInfo/KeyInstructions/init-scalar.c b/clang/test/DebugInfo/KeyInstructions/init-scalar.c
new file mode 100644
index 0000000000000..c212c2a4fd623
--- /dev/null
+++ b/clang/test/DebugInfo/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)

>From 2935186830de115687e4841e0d4c3fba4161a177 Mon Sep 17 00:00:00 2001
From: Orlando Cazalet-Hyams <orlando.hyams at sony.com>
Date: Wed, 21 May 2025 10:21:18 +0100
Subject: [PATCH 2/2] use %clang_cc1 in test

---
 clang/test/DebugInfo/KeyInstructions/init-scalar.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/clang/test/DebugInfo/KeyInstructions/init-scalar.c b/clang/test/DebugInfo/KeyInstructions/init-scalar.c
index c212c2a4fd623..a86c029e47e8c 100644
--- a/clang/test/DebugInfo/KeyInstructions/init-scalar.c
+++ b/clang/test/DebugInfo/KeyInstructions/init-scalar.c
@@ -1,7 +1,7 @@
-// RUN: %clang -gkey-instructions -x c++ %s -gmlt -gcolumn-info -S -emit-llvm -o - \
+// RUN: %clang_cc1 -gkey-instructions -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 -gkey-instructions -x c %s -gmlt -gcolumn-info -S -emit-llvm -o - \
+// RUN: %clang_cc1 -gkey-instructions -x c %s -debug-info-kind=line-tables-only -emit-llvm -o - \
 // RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
 
 void a() {
@@ -10,10 +10,8 @@ void a() {
 // 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)