[CIR] Upstream support for IncompleteArrayType (#144138)

This change adds the basic support for IncompleteArray

Issue #130197

Author: AmrDeveloper

clang/lib/CIR/CodeGen/CIRGenTypes.cpp

@@ -416,6 +416,22 @@ mlir::Type CIRGenTypes::convertType(QualType type) {
     break;
   }
 
+  case Type::IncompleteArray: {
+    const IncompleteArrayType *arrTy = cast<IncompleteArrayType>(ty);
+    if (arrTy->getIndexTypeCVRQualifiers() != 0)
+      cgm.errorNYI(SourceLocation(), "non trivial array types", type);
+
+    mlir::Type elemTy = convertTypeForMem(arrTy->getElementType());
+    // int X[] -> [0 x int], unless the element type is not sized.  If it is
+    // unsized (e.g. an incomplete record) just use [0 x i8].
+    if (!builder.isSized(elemTy)) {
+      elemTy = cgm.SInt8Ty;
+    }
+
+    resultType = cir::ArrayType::get(elemTy, 0);
+    break;
+  }
+
   case Type::ConstantArray: {
     const ConstantArrayType *arrTy = cast<ConstantArrayType>(ty);
     mlir::Type elemTy = convertTypeForMem(arrTy->getElementType());

clang/test/CIR/CodeGen/struct.c

@@ -19,6 +19,7 @@
 // CIR-DAG: !rec_CycleEnd = !cir.record<struct "CycleEnd" {!cir.ptr<!cir.record<struct "CycleStart" {!cir.ptr<!cir.record<struct "CycleMiddle" {!cir.ptr<!cir.record<struct "CycleEnd">>}>>}>>}>
 // CIR-DAG: !rec_CycleMiddle = !cir.record<struct "CycleMiddle" {!cir.ptr<!rec_CycleEnd>}>
 // CIR-DAG: !rec_CycleStart = !cir.record<struct "CycleStart" {!cir.ptr<!rec_CycleMiddle>}>
+// CIR-DAG: !rec_IncompleteArray = !cir.record<struct "IncompleteArray" {!cir.array<!s32i x 0>}>
 // LLVM-DAG: %struct.CompleteS = type { i32, i8 }
 // LLVM-DAG: %struct.OuterS = type { %struct.InnerS, i32 }
 // LLVM-DAG: %struct.InnerS = type { i32, i8 }
@@ -30,6 +31,7 @@
 // LLVM-DAG: %struct.CycleStart = type { ptr }
 // LLVM-DAG: %struct.CycleMiddle = type { ptr }
 // LLVM-DAG: %struct.CycleEnd = type { ptr }
+// LLVM-DAG: %struct.IncompleteArray = type { [0 x i32] }
 // OGCG-DAG: %struct.CompleteS = type { i32, i8 }
 // OGCG-DAG: %struct.OuterS = type { %struct.InnerS, i32 }
 // OGCG-DAG: %struct.InnerS = type { i32, i8 }
@@ -41,6 +43,7 @@
 // OGCG-DAG: %struct.CycleStart = type { ptr }
 // OGCG-DAG: %struct.CycleMiddle = type { ptr }
 // OGCG-DAG: %struct.CycleEnd = type { ptr }
+// OGCG-DAG: %struct.IncompleteArray = type { [0 x i32] }
 
 struct CompleteS {
   int a;
@@ -149,6 +152,16 @@ struct CycleEnd {
 // LLVM-DAG:  @end = global %struct.CycleEnd zeroinitializer
 // OGCG-DAG:  @end = global %struct.CycleEnd zeroinitializer
 
+struct IncompleteArray {
+  int array[];
+} incomplete;
+
+// CIR: cir.global external @incomplete = #cir.zero : !rec_IncompleteArray
+
+// LLVM-DAG: global %struct.IncompleteArray zeroinitializer
+
+// OGCG-DAG: global %struct.IncompleteArray zeroinitializer
+
 void f(void) {
   struct IncompleteS *p;
 }
@@ -313,3 +326,4 @@ void f6(struct CycleStart *start) {
 // OGCG:   %[[MIDDLE:.*]] = getelementptr inbounds nuw %struct.CycleStart, ptr %{{.*}}, i32 0, i32 0
 // OGCG:   %[[END:.*]] = getelementptr inbounds nuw %struct.CycleMiddle, ptr %{{.*}}, i32 0, i32 0
 // OGCG:   %[[START2:.*]] = getelementptr inbounds nuw %struct.CycleEnd, ptr %{{.*}}, i32 0, i32 0
+