[Clang][Sema] Add special handling of mfloat8 in initializer lists (#125097)

This patch fixes assertion failures in clang, caused by unique
properties of _mfp8 type, namely it not being either scalar or vector
type and it not being either integer or float type.

Author: Lukacma

clang/lib/AST/ExprConstant.cpp

@@ -11172,6 +11172,11 @@ VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
   QualType EltTy = VT->getElementType();
   SmallVector<APValue, 4> Elements;
 
+  // MFloat8 type doesn't have constants and thus constant folding
+  // is impossible.
+  if (EltTy->isMFloat8Type())
+    return false;
+
   // The number of initializers can be less than the number of
   // vector elements. For OpenCL, this can be due to nested vector
   // initialization. For GCC compatibility, missing trailing elements

clang/lib/Sema/SemaInit.cpp

@@ -1590,7 +1590,8 @@ void InitListChecker::CheckSubElementType(const InitializedEntity &Entity,
 
   } else {
     assert((ElemType->isRecordType() || ElemType->isVectorType() ||
-            ElemType->isOpenCLSpecificType()) && "Unexpected type");
+            ElemType->isOpenCLSpecificType() || ElemType->isMFloat8Type()) &&
+           "Unexpected type");
 
     // C99 6.7.8p13:
     //

clang/test/CodeGen/AArch64/fp8-init-list.c

@@ -0,0 +1,59 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
+
+// RUN: %clang_cc1        -triple aarch64-none-linux-gnu -target-feature +neon -O2 -Werror -Wall -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -x c++ -triple aarch64-none-linux-gnu -target-feature +neon -O2 -Werror -Wall -emit-llvm -o - %s | FileCheck %s -check-prefix CHECK-CXX
+
+// RUN: %clang_cc1        -triple aarch64-none-linux-gnu -target-feature +neon -O2 -Werror -Wall -S -o /dev/null %s
+
+// REQUIRES: aarch64-registered-target
+
+#include <arm_neon.h>
+
+// CHECK-LABEL: define dso_local <8 x i8> @vector_init_test(
+// CHECK-SAME: <1 x i8> [[X:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[VECINIT14:%.*]] = shufflevector <1 x i8> [[X]], <1 x i8> poison, <8 x i32> zeroinitializer
+// CHECK-NEXT:    ret <8 x i8> [[VECINIT14]]
+//
+// CHECK-CXX-LABEL: define dso_local <8 x i8> @_Z16vector_init_testu6__mfp8(
+// CHECK-CXX-SAME: <1 x i8> [[X:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
+// CHECK-CXX-NEXT:  [[ENTRY:.*:]]
+// CHECK-CXX-NEXT:    [[VECINIT14:%.*]] = shufflevector <1 x i8> [[X]], <1 x i8> poison, <8 x i32> zeroinitializer
+// CHECK-CXX-NEXT:    ret <8 x i8> [[VECINIT14]]
+//
+mfloat8x8_t vector_init_test(__mfp8 x) {
+   return (mfloat8x8_t) {x, x, x, x, x, x, x, x};
+}
+
+struct S {
+    __mfp8 x;
+};
+
+struct S s;
+
+// CHECK-LABEL: define dso_local void @f(
+// CHECK-SAME: <1 x i8> [[X:%.*]]) local_unnamed_addr #[[ATTR1:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    store <1 x i8> [[X]], ptr @s, align 1, !tbaa [[TBAA2:![0-9]+]]
+// CHECK-NEXT:    ret void
+//
+// CHECK-CXX-LABEL: define dso_local void @_Z1fu6__mfp8(
+// CHECK-CXX-SAME: <1 x i8> [[X:%.*]]) local_unnamed_addr #[[ATTR1:[0-9]+]] {
+// CHECK-CXX-NEXT:  [[ENTRY:.*:]]
+// CHECK-CXX-NEXT:    store <1 x i8> [[X]], ptr @s, align 1, !tbaa [[TBAA2:![0-9]+]]
+// CHECK-CXX-NEXT:    ret void
+//
+void f(__mfp8 x) {
+    s = (struct S){x};
+}
+//.
+// CHECK: [[TBAA2]] = !{[[META3:![0-9]+]], [[META3]], i64 0}
+// CHECK: [[META3]] = !{!"__mfp8", [[META4:![0-9]+]], i64 0}
+// CHECK: [[META4]] = !{!"omnipotent char", [[META5:![0-9]+]], i64 0}
+// CHECK: [[META5]] = !{!"Simple C/C++ TBAA"}
+//.
+// CHECK-CXX: [[TBAA2]] = !{[[META3:![0-9]+]], [[META3]], i64 0}
+// CHECK-CXX: [[META3]] = !{!"__mfp8", [[META4:![0-9]+]], i64 0}
+// CHECK-CXX: [[META4]] = !{!"omnipotent char", [[META5:![0-9]+]], i64 0}
+// CHECK-CXX: [[META5]] = !{!"Simple C++ TBAA"}
+//.