[ARM, AArch64] Fix passing of structures with aligned base classes

RecordLayout::UnadjustedAlignment was documented as "Maximum of the
alignments of the record members in characters", but
RecordLayout::getUnadjustedAlignment(), which just returns
UnadjustedAlignment, was documented as getting "the record alignment in
characters, before alignment adjustement." These are not the same thing:
the former excludes alignment of base classes, the latter takes it into
account. ItaniumRecordLayoutBuilder::LayoutBase was setting it according
to the former, but the AAPCS calling convention handling, currently the
only user, relies on it being set according to the latter.

Fixes #135551.

Author: hvdijk

clang/include/clang/AST/RecordLayout.h

@@ -75,8 +75,9 @@ class ASTRecordLayout {
   // performance or backwards compatibility preserving (e.g. AIX-ABI).
   CharUnits PreferredAlignment;
 
-  // UnadjustedAlignment - Maximum of the alignments of the record members in
-  // characters.
+  // UnadjustedAlignment - Alignment of record in characters before alignment
+  // adjustments. Maximum of the alignments of the record members and base
+  // classes in characters.
   CharUnits UnadjustedAlignment;
 
   /// RequiredAlignment - The required alignment of the object.  In the MS-ABI
@@ -186,7 +187,7 @@ class ASTRecordLayout {
   CharUnits getPreferredAlignment() const { return PreferredAlignment; }
 
   /// getUnadjustedAlignment - Get the record alignment in characters, before
-  /// alignment adjustement.
+  /// alignment adjustment.
   CharUnits getUnadjustedAlignment() const { return UnadjustedAlignment; }
 
   /// getSize - Get the record size in characters.

clang/lib/AST/RecordLayoutBuilder.cpp

@@ -1302,6 +1302,7 @@ ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
     setSize(std::max(getSize(), Offset + Layout.getSize()));
 
   // Remember max struct/class alignment.
+  UnadjustedAlignment = std::max(UnadjustedAlignment, PreferredBaseAlign);
   UpdateAlignment(BaseAlign, UnpackedAlignTo, PreferredBaseAlign);
 
   return Offset;

clang/test/CodeGen/aapcs64-align.cpp

@@ -67,25 +67,40 @@ void g3() {
 // CHECK: declare void @f3(i64 noundef, i128)
 // CHECK: declare void @f3m(i64 noundef, i64 noundef, i64 noundef, i64 noundef, i64 noundef, i128)
 
+// Increased natural alignment through a base class.
+struct SB16 : S16 {};
+
+void f4(long, SB16);
+void f4m(long, long, long, long, long, SB16);
+void g4() {
+  SB16 s = {6, 7};
+  f4(1, s);
+  f4m(1, 2, 3, 4, 5, s);
+}
+// CHECK: define{{.*}} void @g4
+// CHECK: call void @f4(i64 noundef 1, i128 129127208515966861318)
+// CHECK: call void @f4m(i64 noundef 1, i64 noundef 2, i64 noundef 3, i64 noundef 4, i64 noundef 5, i128 129127208515966861318)
+// CHECK: declare void @f4(i64 noundef, i128)
+// CHECK: declare void @f4m(i64 noundef, i64 noundef, i64 noundef, i64 noundef, i64 noundef, i128)
 
 // Packed structure.
 struct  __attribute__((packed)) P {
   int x;
   long u;
 };
 
-void f4(int, P);
-void f4m(int, int, int, int, int, P);
-void g4() {
+void f5(int, P);
+void f5m(int, int, int, int, int, P);
+void g5() {
   P s = {6, 7};
-  f4(1, s);
-  f4m(1, 2, 3, 4, 5, s);
+  f5(1, s);
+  f5m(1, 2, 3, 4, 5, s);
 }
-// CHECK: define{{.*}} void @g4()
-// CHECK: call void @f4(i32 noundef 1, [2 x i64] [i64 30064771078, i64 0])
-// CHECK: void @f4m(i32 noundef 1, i32 noundef 2, i32 noundef 3, i32 noundef 4, i32 noundef 5, [2 x i64] [i64 30064771078, i64 0])
-// CHECK: declare void @f4(i32 noundef, [2 x i64])
-// CHECK: declare void @f4m(i32 noundef, i32 noundef, i32 noundef, i32 noundef, i32 noundef, [2 x i64])
+// CHECK: define{{.*}} void @g5()
+// CHECK: call void @f5(i32 noundef 1, [2 x i64] [i64 30064771078, i64 0])
+// CHECK: void @f5m(i32 noundef 1, i32 noundef 2, i32 noundef 3, i32 noundef 4, i32 noundef 5, [2 x i64] [i64 30064771078, i64 0])
+// CHECK: declare void @f5(i32 noundef, [2 x i64])
+// CHECK: declare void @f5m(i32 noundef, i32 noundef, i32 noundef, i32 noundef, i32 noundef, [2 x i64])
 
 
 // Packed structure, overaligned, same as above.
@@ -94,18 +109,18 @@ struct  __attribute__((packed, aligned(16))) P16 {
   long y;
 };
 
-void f5(int, P16);
-void f5m(int, int, int, int, int, P16);
-  void g5() {
-    P16 s = {6, 7};
-    f5(1, s);
-    f5m(1, 2, 3, 4, 5, s);
+void f6(int, P16);
+void f6m(int, int, int, int, int, P16);
+void g6() {
+  P16 s = {6, 7};
+  f6(1, s);
+  f6m(1, 2, 3, 4, 5, s);
 }
-// CHECK: define{{.*}} void @g5()
-// CHECK: call void @f5(i32 noundef 1, [2 x i64] [i64 30064771078, i64 0])
-// CHECK: void @f5m(i32 noundef 1, i32 noundef 2, i32 noundef 3, i32 noundef 4, i32 noundef 5, [2 x i64] [i64 30064771078, i64 0])
-// CHECK: declare void @f5(i32 noundef, [2 x i64])
-// CHECK: declare void @f5m(i32 noundef, i32 noundef, i32 noundef, i32 noundef, i32 noundef, [2 x i64])
+// CHECK: define{{.*}} void @g6()
+// CHECK: call void @f6(i32 noundef 1, [2 x i64] [i64 30064771078, i64 0])
+// CHECK: void @f6m(i32 noundef 1, i32 noundef 2, i32 noundef 3, i32 noundef 4, i32 noundef 5, [2 x i64] [i64 30064771078, i64 0])
+// CHECK: declare void @f6(i32 noundef, [2 x i64])
+// CHECK: declare void @f6m(i32 noundef, i32 noundef, i32 noundef, i32 noundef, i32 noundef, [2 x i64])
 
 //BitInt alignment
 struct BITINT129 {

clang/test/CodeGen/arm-vfp16-arguments2.cpp

@@ -42,7 +42,7 @@ struct S5 : B1 {
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S1 @_Z2f12S1(%struct.S1 returned %s1.coerce)
 struct S1 f1(struct S1 s1) { return s1; }
 
-// CHECK-SOFT: define{{.*}} void @_Z2f22S2(ptr dead_on_unwind noalias writable writeonly sret(%struct.S2) align 8 captures(none) initializes((0, 16)) %agg.result, [4 x i32] %s2.coerce)
+// CHECK-SOFT: define{{.*}} void @_Z2f22S2(ptr dead_on_unwind noalias writable writeonly sret(%struct.S2) align 8 captures(none) initializes((0, 16)) %agg.result, [2 x i64] %s2.coerce)
 // CHECK-HARD: define{{.*}} arm_aapcs_vfpcc [2 x <2 x i32>] @_Z2f22S2([2 x <2 x i32>] returned %s2.coerce)
 // CHECK-FULL: define{{.*}} arm_aapcs_vfpcc %struct.S2 @_Z2f22S2(%struct.S2 %s2.coerce)
 struct S2 f2(struct S2 s2) { return s2; }