Fix sizeof of boolean vector

[Fznamznon]

Summary

Ensure it is at least 8 bits.

Fixes #59801

[tbaeder]

clang/test/SemaCXX/vector-bool.cpp

95

Should be 4 instead of 8, shouldn't it?

[Fznamznon]

clang/test/SemaCXX/vector-bool.cpp

95

This is not four bools.

[erichkeane]

clang/test/SemaCXX/vector-bool.cpp

95

Can you add another couple of 'oddball' sizes and make sure they work out right? I THINK the alignment logic gets it right, but I'd like tests to confirm.

[Fznamznon]

clang/test/SemaCXX/vector-bool.cpp

95

Yes, will fix in a moment.

[Fznamznon]

Adjust the test

[Fznamznon]

clang/test/SemaCXX/vector-bool.cpp

95

Okay, done.

[erichkeane]

clang/test/SemaCXX/vector-bool.cpp

94

How about 33? Does it grow appropriately with alignment?

[Fznamznon]

Add a case with vector of length 33

[Fznamznon]

clang/test/SemaCXX/vector-bool.cpp

94

Its sizeof evaluates to 8. Looking at the code in ASTContext that seems to be appropriate result since 8 is a next power of 2 after 4.

[erichkeane]

Just a couple more I'm concerned about after thinking about it, otherwise this looks about right.

clang/test/SemaCXX/vector-bool.cpp

94

Yep, that makes sense to me! Can you do 1 more group for me?

65, 129, 150, 195, 257?

[Fznamznon]

Add more sizes to test

clang/test/SemaCXX/vector-bool.cpp

94

Sure, done. Seems to be working in the same way.

[erichkeane]

Ok, thank you! This looks right to me :)

clang/lib/AST/ASTContext.cpp

#include "clang/AST/TypeNodes.inc"
   }
 
   case Type::ExtVector:
   case Type::Vector: {
     const auto *VT = cast<VectorType>(T);
     TypeInfo EltInfo = getTypeInfo(VT->getElementType());
     Width = VT->isExtVectorBoolType() ? VT->getNumElements()
                                       : EltInfo.Width * VT->getNumElements();
-    // Enforce at least byte alignment.
+    // Enforce at least byte size and alignment.
+    Width = std::max<unsigned>(8, Width);
     Align = std::max<unsigned>(8, Width);
 
     // If the alignment is not a power of 2, round up to the next power of 2.
     // This happens for non-power-of-2 length vectors.
     if (Align & (Align-1)) {
       Align = llvm::NextPowerOf2(Align);
       Width = llvm::alignTo(Width, Align);
     }

clang/test/SemaCXX/vector-bool.cpp

 
 // Disallow element-wise access.
 bool* ElementRefs() {
   eight_bools.y = false; // expected-error@88 {{illegal vector component name ''y''}}
   &eight_bools.z;        // expected-error@89 {{illegal vector component name ''z''}}
   foo(eight_bools.w);    // expected-error@90 {{illegal vector component name ''w''}}
   foo(eight_bools.wyx);  // expected-error@91 {{illegal vector component name ''wyx''}}
 }
+
+void Sizeof() {
+  using FourBools = bool __attribute__((ext_vector_type(4)));
+  using NineBools = bool __attribute__((ext_vector_type(9)));
+  using TwentyEightBools = bool __attribute__((ext_vector_type(28)));
+  using ThirtyThreeBools = bool __attribute__((ext_vector_type(33)));
+  using SixtyFiveBools = bool __attribute__((ext_vector_type(65)));
+  using Bool129 = bool __attribute__((ext_vector_type(129)));
+  using Bool150 = bool __attribute__((ext_vector_type(150)));
+  using Bool195 = bool __attribute__((ext_vector_type(195)));
+  using Bool257 = bool __attribute__((ext_vector_type(257)));
+  static_assert(sizeof(FourBools) == 1);
+  static_assert(sizeof(EightBools) == 1);
+  static_assert(sizeof(NineBools) == 2);
+  static_assert(sizeof(TwentyEightBools) == 4);
+  static_assert(sizeof(ThirtyThreeBools) == 8);
+  static_assert(sizeof(SixtyFiveBools) == 16);
+  static_assert(sizeof(Bool129) == 32);
+  static_assert(sizeof(Bool150) == 32);
+  static_assert(sizeof(Bool195) == 32);
+  static_assert(sizeof(Bool257) == 64);
+}