[SystemZ][z/OS] fix lit test related to alignment

[NancyWang2222]

Summary

This patch is to fix lit test case failure relate to alignment, on z/OS, maximum alignment value for 64 bit mode is 16 and also fixed clang/test/Layout/itanium-union-bitfield.cpp, attribute ((aligned(4))) is needed for bit-field member in Union for z/OS because single bit-field has one byte alignment, this will make sure size and alignment will be correct value on z/OS.

[hubert.reinterpretcast]

@NancyWang2222, the patch description doesn't seem to say much about the bit-field case. Can you expand it?

clang/test/Layout/itanium-union-bitfield.cpp

4–5

This comment is supposed to be true for both of the bit-field declarations, no?

7

I think the macro should be in all caps.

20

I can't help but notice that this does not have the attribute applied.

35

This output does not match the behaviour of the xlclang++ compiler I tried:

union B {
  char f1: 35;
  B();
};

B::B() {}

extern "C" int printf(const char *, ...);
int main(void) {
   B b[1];
   printf("%lld\n", (long long)((char *)(b + 1) - (char *)b));
}

Gives me:

5

as the size of the union.

[abhina.sreeskantharajan]

Hi Nancy, can you set this patch as a child revision of https://reviews.llvm.org/D98864 which sets the maximum alignment.

[NancyWang2222]

clang/test/Layout/itanium-union-bitfield.cpp

7

I will fix it. Thanks

20

it doesnt fail on union B. dump shows:

• Dumping AST Record Layout 0 | union B 0:0-34 | char f1 | [sizeof=8, dsize=5, align=4, | nvsize=5, nvalign=4]

which is what test case expects

35

You are right. xlclang++ has different output from clang. will need to look into it.

[hubert.reinterpretcast]

clang/test/Layout/itanium-union-bitfield.cpp

20

Just pointing out that the comment above and the xlclang++ behaviour below both seem to imply that adding the alignment attribute here should be done. If adding it is currently harmless, then I think it makes sense to add it.

[NancyWang2222]

In D98793#2634510, @abhina.sreeskantharajan wrote:

Hi Nancy, can you set this patch as a child revision of https://reviews.llvm.org/D98864 which sets the maximum alignment.

added. thanks

clang/test/Layout/itanium-union-bitfield.cpp

20

sure. I will add attributes for union B as well. Thanks for pointing it out.

[hubert.reinterpretcast]

LGTM; thanks.

clang/test/AST/alignas_maybe_odr_cleanup.cpp

 // Test without serialization:
 // RUN: %clang_cc1 -fsyntax-only %s -ast-dump | FileCheck %s
 //
 // Test with serialization:
 // RUN: %clang_cc1 -emit-pch -o %t %s
 // RUN: %clang_cc1 -x c++ -include-pch %t -ast-dump-all /dev/null \
 // RUN: | sed -e "s/ <undeserialized declarations>//" -e "s/ imported//" \
 // RUN: | FileCheck %s
 
 struct FOO {
-  static const int vec_align_bytes = 32;
+  static const int vec_align_bytes = 16;
   void foo() {
     double a alignas(vec_align_bytes);
     ;
   }
 };
 
 // CHECK:      |   `-AlignedAttr {{.*}} <col:14> alignas
 // CHECK-NEXT:      |     `-ConstantExpr {{.*}} <col:22> 'int'
-// CHECK-NEXT:      |       |-value: Int 32
+// CHECK-NEXT:      |       |-value: Int 16
 // CHECK-NEXT:      |       `-ImplicitCastExpr {{.*}} <col:22> 'int' <LValueToRValue>
 // CHECK-NEXT:      |         `-DeclRefExpr {{.*}} <col:22> 'const int' lvalue Var {{.*}} 'vec_align_bytes' 'const int' non_odr_use_constant
 // CHECK-NEXT:      `-NullStmt {{.*}} <line:14:5>

clang/test/CodeGen/PR5060-align.c

 // RUN: %clang_cc1 -emit-llvm %s -o - | FileCheck %s
 
-// CHECK: @foo.p = internal global i8 0, align 32
+// CHECK: @foo.p = internal global i8 0, align 16
 char *foo(void) {
-  static char p __attribute__((aligned(32)));
+  static char p __attribute__((aligned(16)));
   return &p;
 }
 
 void bar(long n) {
-  // CHECK: align 32
-  char p[n] __attribute__((aligned(32)));
+  // CHECK: align 16
+  char p[n] __attribute__((aligned(16)));
 }
 

clang/test/Layout/itanium-union-bitfield.cpp

 // RUN: %clang_cc1 -emit-llvm-only -triple %itanium_abi_triple -fdump-record-layouts %s 2>/dev/null \
 // RUN:            | FileCheck %s
 
+// On z/OS, a bit-field has single byte alignment.  Add aligned(4) on z/OS so the union has
+// the same size & alignment as expected.
+#ifdef __MVS__
+#define ALIGN4 __attribute__((aligned(4)))
+#else
+#define ALIGN4
+#endif
+
 union A {
-  int f1: 3;
+  int f1 : 3 ALIGN4;
   A();
 };
 
 A::A() {}
 
 union B {
-  char f1: 35;
+  char f1 : 35 ALIGN4;
   B();
 };
 
 B::B() {}
 
 // CHECK:*** Dumping AST Record Layout
 // CHECK-NEXT:     0 | union A
 // CHECK-NEXT: 0:0-2 |   int f1
 // CHECK-NEXT:       | [sizeof=4, dsize=1, align=4{{(, preferredalign=4,)?}}
 // CHECK-NEXT:       |  nvsize=1, nvalign=4{{(, preferrednvalign=4)?}}]
 
 // CHECK:*** Dumping AST Record Layout
 // CHECK-NEXT:      0 | union B
 // CHECK-NEXT: 0:0-34 |   char f1
 // CHECK-NEXT:        | [sizeof=8, dsize=5, align=4{{(, preferredalign=4,)?}}
 // CHECK-NEXT:        |  nvsize=5, nvalign=4{{(, preferrednvalign=4)?}}]