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

`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 #62207

Reviewed By: erichkeane, shafik

Differential Revision: https://reviews.llvm.org/D149436

Author: Fznamznon

clang/docs/ReleaseNotes.rst

@@ -337,6 +337,9 @@ Bug Fixes in This Version
   (`#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
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/CodeGen/CGExprConstant.cpp

@@ -1730,7 +1730,7 @@ llvm::Constant *ConstantEmitter::emitForMemory(CodeGenModule &CGM,
   }
 
   // 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);
   }

clang/test/CodeGen/ext-int.c

@@ -3,6 +3,10 @@
 // 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);