llvm: correctly bitcast for memset intrinsic path

src/codegen/llvm/FuncGen.zig

@@ -5127,7 +5127,7 @@ fn airMemset(self: *FuncGen, inst: Air.Inst.Index, safety: bool) Allocator.Error
     const value = try self.resolveInst(bin_op.rhs);
     const elem_abi_size = elem_ty.abiSize(zcu);
 
-    if (elem_abi_size == 1) {
+    if (elem_abi_size == 1 and elem_ty.bitSize(zcu) == 8) {
         // In this case we can take advantage of LLVM's intrinsic.
         const fill_byte = try self.bitCast(value, elem_ty, Type.u8);
         const len = try self.sliceOrArrayLenInBytes(dest_slice, ptr_ty);

test/behavior/memset.zig

@@ -190,3 +190,11 @@ test "@memset a global array" {
     @memset(&S.buf, S.buf[0] + 333);
     try expect(S.buf[0] == 789);
 }
+
+test "@memset array of booleans" {
+    const S = struct {
+        var x: bool = false;
+        var y: [1]bool = undefined;
+    };
+    @memset(&S.y, S.x);
+}