[clang] [CIR] Implement CK_LValueToRValueBitCast for ComplexType (PR #150296)

[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 CK_LValueToRValueBitCast for ComplexType

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

---
Full diff: https://github.com/llvm/llvm-project/pull/150296.diff


2 Files Affected:

- (modified) clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp (+6-2) 
- (modified) clang/test/CIR/CodeGen/complex-cast.cpp (+25) 


``````````diff
diff --git a/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp b/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
index d52da0cb32c53..7f2e2ce311846 100644
--- a/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenExprComplex.cpp
@@ -194,8 +194,12 @@ mlir::Value ComplexExprEmitter::emitCast(CastKind ck, Expr *op,
   }
 
   case CK_LValueToRValueBitCast: {
-    cgf.cgm.errorNYI("ComplexExprEmitter::emitCast CK_LValueToRValueBitCast");
-    return {};
+    LValue sourceLVal = cgf.emitLValue(op);
+    Address addr = sourceLVal.getAddress().withElementType(
+        builder, cgf.convertTypeForMem(destTy));
+    LValue destLV = cgf.makeAddrLValue(addr, destTy);
+    assert(!cir::MissingFeatures::opTBAA());
+    return emitLoadOfLValue(destLV, op->getExprLoc());
   }
 
   case CK_BitCast:
diff --git a/clang/test/CIR/CodeGen/complex-cast.cpp b/clang/test/CIR/CodeGen/complex-cast.cpp
index 94f47e4730cc2..a5ae21e82b7c6 100644
--- a/clang/test/CIR/CodeGen/complex-cast.cpp
+++ b/clang/test/CIR/CodeGen/complex-cast.cpp
@@ -326,3 +326,28 @@ void complex_to_complex_cast() {
 // OGCG: store i32 %[[REAL_INT_CAST]], ptr {{.*}}, align 4
 // OGCG: store i32 %[[IMAG_INT_CAST]], ptr getelementptr inbounds nuw ({ i32, i32 }, ptr {{.*}}, i32 0, i32 1), align 4
 
+
+void lvalue_to_rvalue_bitcast() {
+  void *a;
+  int _Complex b = __builtin_bit_cast(int _Complex, a);
+}
+
+// CIR-BEFORE: %{{.*}} = cir.cast(bitcast, %{{.*}} : !cir.ptr<!cir.ptr<!void>>), !cir.ptr<!cir.complex<!s32i>>
+
+// CIR-AFTER: %{{.*}} = cir.cast(bitcast, %{{.*}} : !cir.ptr<!cir.ptr<!void>>), !cir.ptr<!cir.complex<!s32i>>
+
+// LLVM: %[[PTR_ADDR:.*]] = alloca ptr, i64 1, align 8
+// LLVM: %[[COMPLEX_ADDR:.*]] = alloca { i32, i32 }, i64 1, align 4
+// LLVM: %[[PTR_TO_COMPLEX:.*]] = load { i32, i32 }, ptr %[[PTR_ADDR]], align 8
+// LLVM: store { i32, i32 } %[[PTR_TO_COMPLEX]], ptr %[[COMPLEX_ADDR]], align 4
+
+// OGCG: %[[A_ADDR:.*]] = alloca ptr, align 8
+// OGCG: %[[B_ADDR:.*]] = alloca { i32, i32 }, align 4
+// OGCG: %[[A_REAL_PTR:.*]] = getelementptr inbounds nuw { i32, i32 }, ptr %[[A_ADDR]], i32 0, i32 0
+// OGCG: %[[A_REAL:.*]] = load i32, ptr %[[A_REAL_PTR]], align 8
+// OGCG: %[[A_IMAG_PTR:.*]] = getelementptr inbounds nuw { i32, i32 }, ptr %[[A_ADDR]], i32 0, i32 1
+// OGCG: %[[A_IMAG:.*]] = load i32, ptr %[[A_IMAG_PTR]], align 4
+// OGCG: %[[B_REAL_PTR:.*]] = getelementptr inbounds nuw { i32, i32 }, ptr %[[B_ADDR]], i32 0, i32 0
+// OGCG: %[[B_IMAG_PTR:.*]] = getelementptr inbounds nuw { i32, i32 }, ptr %[[B_ADDR]], i32 0, i32 1
+// OGCG: store i32 %[[A_REAL]], ptr %[[B_REAL_PTR]], align 4
+// OGCG: store i32 %[[A_IMAG]], ptr %[[B_IMAG_PTR]], align 4

``````````

</details>


https://github.com/llvm/llvm-project/pull/150296