[clang] Do not attempt to zero-extend _BitInt(1) when not required

[Fznamznon]

Summary

ConvertTypeForMem doesn't return wider type for _BitInt unless it is
used in a bitfield, so no need to extend when trying to initialize a
global variable.

Fixes https://github.com/llvm/llvm-project/issues/62207

[erichkeane]

This looks right to me, thanks!

[shafik]

LGTM

clang/test/CodeGen/ext-int.c

8

Interesting, it looks like true and false are valid for i1 all the time.

clang/docs/ReleaseNotes.rst

 - Fix crash when handling undefined template partial specialization
   (`#61356 <https://github.com/llvm/llvm-project/issues/61356>`_)
 - Fix premature substitution into the constraints of an inherited constructor.
 - Fix crash when attempting to perform parenthesized initialization of an
   aggregate with a base class with only non-public constructors.
   (`#62296 <https://github.com/llvm/llvm-project/issues/62296>`_)
 - Fix a stack overflow issue when evaluating ``consteval`` default arguments.
   (`#60082` <https://github.com/llvm/llvm-project/issues/60082>`_)
+- Fix the assertion hit when generating code for global variable initializer of
+  _BitInt(1) type.
+  (`#62207 <https://github.com/llvm/llvm-project/issues/62207>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 Bug Fixes to Attribute Support
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 - Fixed a bug where attribute annotations on type specifiers (enums, classes,
   structs, unions, and scoped enums) were not properly ignored, resulting in

clang/lib/CodeGen/CGExprConstant.cpp

llvm::Constant *elts[] = {
       C,
       llvm::ConstantAggregateZero::get(
           llvm::ArrayType::get(CGM.Int8Ty, (outerSize - innerSize) / 8))
     };
     return llvm::ConstantStruct::getAnon(elts);
   }
 
   // Zero-extend bool.
-  if (C->getType()->isIntegerTy(1)) {
+  if (C->getType()->isIntegerTy(1) && !destType->isBitIntType()) {
     llvm::Type *boolTy = CGM.getTypes().ConvertTypeForMem(destType);
     return llvm::ConstantExpr::getZExt(C, boolTy);
   }
 
   return C;
 }
 
 llvm::Constant *ConstantEmitter::tryEmitPrivate(const Expr *E,

clang/test/CodeGen/ext-int.c

 // RUN: %clang_cc1 -triple x86_64-gnu-linux -O3 -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,CHECK64
 // RUN: %clang_cc1 -triple x86_64-windows-pc -O3 -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,CHECK64
 // RUN: %clang_cc1 -triple i386-gnu-linux -O3 -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,LIN32
 // RUN: %clang_cc1 -triple i386-windows-pc -O3 -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefixes=CHECK,WIN32
 
+//GH62207
+unsigned _BitInt(1) GlobSize1 = 0;
+// CHECK: @GlobSize1 = {{.*}}global i1 false
+
 void GenericTest(_BitInt(3) a, unsigned _BitInt(3) b, _BitInt(4) c) {
   // CHECK: define {{.*}}void @GenericTest
   int which = _Generic(a, _BitInt(3): 1, unsigned _BitInt(3) : 2, _BitInt(4) : 3);
   // CHECK: store i32 1
   int which2 = _Generic(b, _BitInt(3): 1, unsigned _BitInt(3) : 2, _BitInt(4) : 3);
   // CHECK: store i32 2
   int which3 = _Generic(c, _BitInt(3): 1, unsigned _BitInt(3) : 2, _BitInt(4) : 3);
   // CHECK: store i32 3