[CIR] Implement support for GNUNullExpr

[AmrDeveloper]

Implement support for GNUNullExpr

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clangir

Author: Amr Hesham (AmrDeveloper)

Changes

Implement support for GNUNullExpr

---

Full diff: https://github.com/llvm/llvm-project/pull/167715.diff

2 Files Affected:

• (modified) clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp (+4)
• (added) clang/test/CIR/CodeGen/gnu-null.cpp (+28)

diff --git a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
index c1a36134d8942..8514b0bff6d8e 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp
@@ -197,6 +197,10 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
     return emitNullValue(e->getType(), cgf.getLoc(e->getSourceRange()));
   }
 
+  mlir::Value VisitGNUNullExpr(const GNUNullExpr *e) {
+    return emitNullValue(e->getType(), cgf.getLoc(e->getSourceRange()));
+  }
+
   mlir::Value VisitOpaqueValueExpr(OpaqueValueExpr *e) {
     if (e->isGLValue())
       return emitLoadOfLValue(cgf.getOrCreateOpaqueLValueMapping(e),
diff --git a/clang/test/CIR/CodeGen/gnu-null.cpp b/clang/test/CIR/CodeGen/gnu-null.cpp
new file mode 100644
index 0000000000000..d1d15f2007621
--- /dev/null
+++ b/clang/test/CIR/CodeGen/gnu-null.cpp
@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+void gnu_null_expr() {
+  long a = __null;
+  int *b = __null;
+}
+
+// CIR: %[[A_ADDR:.*]] = cir.alloca !s64i, !cir.ptr<!s64i>, ["a", init]
+// CIR: %[[B_ADDR:.*]] = cir.alloca !cir.ptr<!s32i>, !cir.ptr<!cir.ptr<!s32i>>, ["b", init]
+// CIR: %[[CONST_0:.*]] = cir.const #cir.int<0> : !s64i
+// CIR: cir.store {{.*}} %[[CONST_0]], %[[A_ADDR]] : !s64i, !cir.ptr<!s64i>
+// CIR: %[[CONST_NULL:.*]] = cir.const #cir.ptr<null> : !cir.ptr<!s32i>
+// CIR: cir.store {{.*}} %[[CONST_NULL]], %[[B_ADDR]] : !cir.ptr<!s32i>, !cir.ptr<!cir.ptr<!s32i>>
+
+// LLVM: %[[A_ADDR:.*]] = alloca i64, i64 1, align 8
+// LLVM: %[[B_ADDR:.*]] = alloca ptr, i64 1, align 8
+// LLVM: store i64 0, ptr %[[A_ADDR]], align 8
+// LLVM: store ptr null, ptr %[[B_ADDR]], align 8
+
+// OGCG: %[[A_ADDR:.*]] = alloca i64, align 8
+// OGCG: %[[B_ADDR:.*]] = alloca ptr, align 8
+// OGCG: store i64 0, ptr %[[A_ADDR]], align 8
+// OGCG: store ptr null, ptr %[[B_ADDR]], align 8

[andykaylor]

lgtm