[clang] [CIR] Implement MemberExpr support for ComplexType (PR #154027)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clangir

Author: Amr Hesham (AmrDeveloper)

<details>
<summary>Changes</summary>

This change adds support for the MemberExpr ComplexType

Issue: https://github.com/llvm/llvm-project/issues/141365

---
Full diff: https://github.com/llvm/llvm-project/pull/154027.diff


4 Files Affected:

- (modified) clang/lib/CIR/CodeGen/CIRGenExpr.cpp (+21-2) 
- (modified) clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp (+8) 
- (modified) clang/lib/CIR/CodeGen/CIRGenFunction.h (+2-1) 
- (modified) clang/test/CIR/CodeGen/complex.cpp (+30) 


``````````diff
diff --git a/clang/lib/CIR/CodeGen/CIRGenExpr.cpp b/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
index 8bcca6f5d1803..707ae83d0d1b0 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExpr.cpp
@@ -2063,8 +2063,8 @@ cir::AllocaOp CIRGenFunction::createTempAlloca(mlir::Type ty,
 ///
 /// For named members of enums, this is the only way they are emitted.
 CIRGenFunction::ConstantEmission
-CIRGenFunction::tryEmitAsConstant(DeclRefExpr *refExpr) {
-  ValueDecl *value = refExpr->getDecl();
+CIRGenFunction::tryEmitAsConstant(const DeclRefExpr *refExpr) {
+  const ValueDecl *value = refExpr->getDecl();
 
   // There is a lot more to do here, but for now only EnumConstantDecl is
   // supported.
@@ -2097,6 +2097,25 @@ CIRGenFunction::tryEmitAsConstant(DeclRefExpr *refExpr) {
   return ConstantEmission::forValue(cstToEmit);
 }
 
+static DeclRefExpr *tryToConvertMemberExprToDeclRefExpr(CIRGenFunction &cgf,
+                                                        const MemberExpr *me) {
+  if (auto *vd = dyn_cast<VarDecl>(me->getMemberDecl())) {
+    // Try to emit static variable member expressions as DREs.
+    return DeclRefExpr::Create(
+        cgf.getContext(), NestedNameSpecifierLoc(), SourceLocation(), vd,
+        /*RefersToEnclosingVariableOrCapture=*/false, me->getExprLoc(),
+        me->getType(), me->getValueKind(), nullptr, nullptr, me->isNonOdrUse());
+  }
+  return nullptr;
+}
+
+CIRGenFunction::ConstantEmission
+CIRGenFunction::tryEmitAsConstant(const MemberExpr *me) {
+  if (DeclRefExpr *dre = tryToConvertMemberExprToDeclRefExpr(*this, me))
+    return tryEmitAsConstant(dre);
+  return ConstantEmission();
+}
+
 mlir::Value CIRGenFunction::emitScalarConstant(
     const CIRGenFunction::ConstantEmission &constant, Expr *e) {
   assert(constant && "not a constant");
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp b/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
index 85cd0282ffc2a..98310e63daaf4 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
@@ -62,6 +62,14 @@ class ComplexExprEmitter : public StmtVisitor<ComplexExprEmitter, mlir::Value> {
   mlir::Value VisitImplicitCastExpr(ImplicitCastExpr *e);
   mlir::Value VisitInitListExpr(InitListExpr *e);
 
+  mlir::Value VisitMemberExpr(MemberExpr *me) {
+    if (CIRGenFunction::ConstantEmission constant = cgf.tryEmitAsConstant(me)) {
+      cgf.emitIgnoredExpr(me->getBase());
+      return emitConstant(constant, me);
+    }
+    return emitLoadOfLValue(me);
+  }
+
   mlir::Value VisitCompoundLiteralExpr(CompoundLiteralExpr *e) {
     return emitLoadOfLValue(e);
   }
diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.h b/clang/lib/CIR/CodeGen/CIRGenFunction.h
index 9a887ec047f86..7096c8189b7db 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.h
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.h
@@ -452,7 +452,8 @@ class CIRGenFunction : public CIRGenTypeCache {
     }
   };
 
-  ConstantEmission tryEmitAsConstant(DeclRefExpr *refExpr);
+  ConstantEmission tryEmitAsConstant(const DeclRefExpr *refExpr);
+  ConstantEmission tryEmitAsConstant(const MemberExpr *me);
 
   struct AutoVarEmission {
     const clang::VarDecl *Variable;
diff --git a/clang/test/CIR/CodeGen/complex.cpp b/clang/test/CIR/CodeGen/complex.cpp
index bd7de9a3a5039..90504bee3549f 100644
--- a/clang/test/CIR/CodeGen/complex.cpp
+++ b/clang/test/CIR/CodeGen/complex.cpp
@@ -799,3 +799,33 @@ void foo30() {
 // OGCG: %[[A_IMAG_PTR:.*]] = getelementptr inbounds nuw { float, float }, ptr %[[A_ADDR]], i32 0, i32 1
 // OGCG: store float 1.000000e+00, ptr %[[A_REAL_PTR]], align 4
 // OGCG: store float 0.000000e+00, ptr %[[A_IMAG_PTR]], align 4
+
+void foo31() {
+  struct Wrapper {
+    int _Complex c;
+  };
+
+  Wrapper w;
+  int r = __real__ w.c;
+}
+
+// CIR: %[[W_ADDR:.*]] = cir.alloca !rec_Wrapper, !cir.ptr<!rec_Wrapper>, ["w"]
+// CIR: %[[REAL_ADDR:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["r", init]
+// CIR: %[[ELEM_PTR:.*]] = cir.get_member %[[W_ADDR]][0] {name = "c"} : !cir.ptr<!rec_Wrapper> -> !cir.ptr<!cir.complex<!s32i>>
+// CIR: %[[TMP_ELEM_PTR:.*]] = cir.load{{.*}} %[[ELEM_PTR]] : !cir.ptr<!cir.complex<!s32i>>, !cir.complex<!s32i>
+// CIR: %[[REAL:.*]] = cir.complex.real %[[TMP_ELEM_PTR]] : !cir.complex<!s32i> -> !s32i
+// CIR: cir.store{{.*}} %[[REAL]], %[[REAL_ADDR]] : !s32i, !cir.ptr<!s32i>
+
+// LLVM: %[[W_ADDR:.*]] = alloca %struct.Wrapper, i64 1, align 4
+// LLVM: %[[REAL_ADDR:.*]] = alloca i32, i64 1, align 4
+// LLVM: %[[ELEM_PTR:.*]] = getelementptr %struct.Wrapper, ptr %[[W_ADDR]], i32 0, i32 0
+// LLVM: %[[TMP_ELEM_PTR:.*]] = load { i32, i32 }, ptr %[[ELEM_PTR]], align 4
+// LLVM: %[[REAL:.*]] = extractvalue { i32, i32 } %[[TMP_ELEM_PTR]], 0
+// LLVM: store i32 %[[REAL]], ptr %[[REAL_ADDR]], align 4
+
+// OGCG: %[[W_ADDR:.*]] = alloca %struct.Wrapper, align 4
+// OGCG: %[[REAL_ADDR:.*]] = alloca i32, align 4
+// OGCG: %[[ELEM_PTR:.*]] = getelementptr inbounds nuw %struct.Wrapper, ptr %[[W_ADDR]], i32 0, i32 0
+// OGCG: %[[REAL_PTR:.*]] = getelementptr inbounds nuw { i32, i32 }, ptr %[[ELEM_PTR]], i32 0, i32 0
+// OGCG: %[[REAL:.*]] = load i32, ptr %[[REAL_PTR]], align 4
+// OGCG: store i32 %[[REAL]], ptr %[[REAL_ADDR]], align 4

``````````

</details>


https://github.com/llvm/llvm-project/pull/154027