[CIR] Handle default arguments in ctors

[andykaylor]

This adds the scalar expression visitor needed to handle default arguments being passed to constructors.

[llvmbot]

@llvm/pr-subscribers-clangir

@llvm/pr-subscribers-clang

Author: Andy Kaylor (andykaylor)

Changes

This adds the scalar expression visitor needed to handle default arguments being passed to constructors.

---

Full diff: https://github.com/llvm/llvm-project/pull/168649.diff

2 Files Affected:

• (modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+4)
• (modified) clang/test/CIR/CodeGen/defaultarg.cpp (+22)

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index f777562ba6309..26e329250b6f3 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -711,6 +711,10 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     return Visit(e->getSubExpr());
   }
 
+  mlir::Value VisitCXXDefaultArgExpr(CXXDefaultArgExpr *dae) {
+    CIRGenFunction::CXXDefaultArgExprScope Scope(cgf, dae);
+    return Visit(dae->getExpr());
+  }
   mlir::Value VisitCXXDefaultInitExpr(CXXDefaultInitExpr *die) {
     CIRGenFunction::CXXDefaultInitExprScope scope(cgf, die);
     return Visit(die->getExpr());
diff --git a/clang/test/CIR/CodeGen/defaultarg.cpp b/clang/test/CIR/CodeGen/defaultarg.cpp
index 807230bd003f5..29c929ccd7838 100644
--- a/clang/test/CIR/CodeGen/defaultarg.cpp
+++ b/clang/test/CIR/CodeGen/defaultarg.cpp
@@ -30,3 +30,25 @@ void foo() {
 // OGCG:   %[[TMP0:.*]] = alloca i32
 // OGCG:   store i32 42, ptr %[[TMP0]]
 // OGCG:   call void @_Z3barRKi(ptr {{.*}} %[[TMP0]])
+
+struct S
+{
+  S(int n = 2);
+};
+
+void test_ctor_defaultarg() {
+  S s;
+}
+
+// CIR: cir.func {{.*}} @_Z20test_ctor_defaultargv()
+// CIR:   %[[S:.*]] = cir.alloca !rec_S, !cir.ptr<!rec_S>, ["s", init]
+// CIR:   %[[TWO:.*]] = cir.const #cir.int<2> : !s32i
+// CIR:   cir.call @_ZN1SC1Ei(%[[S]], %[[TWO]]) : (!cir.ptr<!rec_S>, !s32i) -> ()
+
+// LLVM: define{{.*}} @_Z20test_ctor_defaultargv()
+// LLVM:   %[[S:.*]] = alloca %struct.S
+// LLVM:   call void @_ZN1SC1Ei(ptr %[[S]], i32 2)
+
+// OGCG: define{{.*}} @_Z20test_ctor_defaultargv()
+// OGCG:   %[[S:.*]] = alloca %struct.S
+// OGCG:   call void @_ZN1SC1Ei(ptr{{.*}} %[[S]], i32 {{.*}} 2)

[github-actions]

🐧 Linux x64 Test Results

• 112019 tests passed
• 4077 tests skipped

[xlauko]

lgtm % nit

[xlauko]

Suggested change

	CIRGenFunction::CXXDefaultArgExprScope Scope(cgf, dae);
	CIRGenFunction::CXXDefaultArgExprScope scope(cgf, dae);