[clang] [CIR] Implement GenericSelectionExpr for AggregateExpr (PR #161003)

[Amr Hesham via cfe-commits]

=?utf-8?q?“Amr?= <amr96 at programmer.net>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/161003 at github.com>


https://github.com/AmrDeveloper updated https://github.com/llvm/llvm-project/pull/161003

>From d9f88a30f04bb23bdcb41451b9f32aa657016b8c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CAmr?= <amr96 at programmer.net>
Date: Sat, 27 Sep 2025 13:00:12 +0200
Subject: [PATCH 1/2] [CIR] Implement GenericSelectionExpr for AggregateExpr

---
 clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp |  3 +-
 clang/lib/CIR/CodeGen/CIRGenFunction.cpp      |  2 ++
 clang/test/CIR/CodeGen/struct.cpp             | 28 +++++++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
index af42d1d882ae0..1e987f3bedc7e 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprAggregate.cpp
@@ -133,8 +133,7 @@ class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
   }
   void VisitParenExpr(ParenExpr *pe) { Visit(pe->getSubExpr()); }
   void VisitGenericSelectionExpr(GenericSelectionExpr *ge) {
-    cgf.cgm.errorNYI(ge->getSourceRange(),
-                     "AggExprEmitter: VisitGenericSelectionExpr");
+    Visit(ge->getResultExpr());
   }
   void VisitCoawaitExpr(CoawaitExpr *e) {
     cgf.cgm.errorNYI(e->getSourceRange(), "AggExprEmitter: VisitCoawaitExpr");
diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
index 9d98361a8b6a2..f836e29866036 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
@@ -832,6 +832,8 @@ LValue CIRGenFunction::emitLValue(const Expr *e) {
     return emitCallExprLValue(cast<CallExpr>(e));
   case Expr::ParenExprClass:
     return emitLValue(cast<ParenExpr>(e)->getSubExpr());
+  case Expr::GenericSelectionExprClass:
+    return emitLValue(cast<GenericSelectionExpr>(e)->getResultExpr());
   case Expr::DeclRefExprClass:
     return emitDeclRefLValue(cast<DeclRefExpr>(e));
   case Expr::CStyleCastExprClass:
diff --git a/clang/test/CIR/CodeGen/struct.cpp b/clang/test/CIR/CodeGen/struct.cpp
index 1dc16f3b79497..e7e3ed765aed6 100644
--- a/clang/test/CIR/CodeGen/struct.cpp
+++ b/clang/test/CIR/CodeGen/struct.cpp
@@ -154,3 +154,31 @@ void choose_expr() {
 // OGCG:   %[[B_ADDR:.*]] = alloca %struct.CompleteS, align 4
 // OGCG:   %[[C_ADDR:.*]] = alloca %struct.CompleteS, align 4
 // OGCG:   call void @llvm.memcpy.p0.p0.i64(ptr align 4 %[[C_ADDR]], ptr align 4 %[[A_ADDR]], i64 8, i1 false)
+
+void generic_selection() {
+  CompleteS a;
+  CompleteS b;
+  int c;
+  CompleteS d = _Generic(c, int : a, default: b);
+}
+
+// CIR: cir.func{{.*}} @_Z17generic_selectionv()
+// CIR:   %[[A_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["a"]
+// CIR:   %[[B_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["b"]
+// CIR:   %[[C_ADDR:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["c"]
+// CIR:   %[[D_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["d", init]
+// CIR:   cir.call @_ZN9CompleteSC1ERKS_(%[[D_ADDR]], %[[A_ADDR]]) nothrow : (!cir.ptr<!rec_CompleteS>, !cir.ptr<!rec_CompleteS>) -> ()
+
+// LLVM: define{{.*}} void @_Z17generic_selectionv()
+// LLVM:   %1 = alloca %struct.CompleteS, i64 1, align 4
+// LLVM:   %2 = alloca %struct.CompleteS, i64 1, align 4
+// LLVM:   %3 = alloca i32, i64 1, align 4
+// LLVM:   %4 = alloca %struct.CompleteS, i64 1, align 4
+// LLVM:   call void @_ZN9CompleteSC1ERKS_(ptr %4, ptr %1)
+
+// OGCG: define{{.*}} void @_Z17generic_selectionv()
+// OGCG:   %[[A_ADDR:.*]] = alloca %struct.CompleteS, align 4
+// OGCG:   %[[B_ADDR:.*]] = alloca %struct.CompleteS, align 4
+// OGCG:   %[[C_ADDR:.*]] = alloca i32, align 4
+// OGCG:   %[[D_ADDR:.*]] = alloca %struct.CompleteS, align 4
+// OGCG:   call void @llvm.memcpy.p0.p0.i64(ptr align 4 %[[D_ADDR]], ptr align 4 %[[A_ADDR]], i64 8, i1 false)

>From bf3837f69190df6e1b3e07a8a9e8b77fe83de998 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9CAmr?= <amr96 at programmer.net>
Date: Tue, 30 Sep 2025 19:18:59 +0200
Subject: [PATCH 2/2] Add note about using cir.copy

---
 clang/test/CIR/CodeGen/struct.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/test/CIR/CodeGen/struct.cpp b/clang/test/CIR/CodeGen/struct.cpp
index e7e3ed765aed6..96db82a89977c 100644
--- a/clang/test/CIR/CodeGen/struct.cpp
+++ b/clang/test/CIR/CodeGen/struct.cpp
@@ -167,6 +167,7 @@ void generic_selection() {
 // CIR:   %[[B_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["b"]
 // CIR:   %[[C_ADDR:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["c"]
 // CIR:   %[[D_ADDR:.*]] = cir.alloca !rec_CompleteS, !cir.ptr<!rec_CompleteS>, ["d", init]
+// TODO(cir): Call to default copy constructor should be replaced by `cir.copy` op
 // CIR:   cir.call @_ZN9CompleteSC1ERKS_(%[[D_ADDR]], %[[A_ADDR]]) nothrow : (!cir.ptr<!rec_CompleteS>, !cir.ptr<!rec_CompleteS>) -> ()
 
 // LLVM: define{{.*}} void @_Z17generic_selectionv()