YJIT: Extract SHAPE_ID_NUM_BITS into a constant (#6863)

shape.c

@@ -300,16 +300,10 @@ rb_shape_set_shape(VALUE obj, rb_shape_t* shape)
     rb_shape_set_shape_id(obj, rb_shape_id(shape));
 }
 
-uint8_t
-rb_shape_id_num_bits(void)
-{
-    return SHAPE_ID_NUM_BITS;
-}
-
 int32_t
 rb_shape_id_offset(void)
 {
-    return 8 - rb_shape_id_num_bits() / 8;
+    return sizeof(uintptr_t) - SHAPE_ID_NUM_BITS / sizeof(uintptr_t);
 }
 
 rb_shape_t *

yjit/bindgen/src/main.rs

@@ -85,12 +85,12 @@ fn main() {
         // From shape.h
         .allowlist_function("rb_shape_get_shape_id")
         .allowlist_function("rb_shape_get_shape_by_id")
-        .allowlist_function("rb_shape_id_num_bits")
         .allowlist_function("rb_shape_id_offset")
         .allowlist_function("rb_shape_get_iv_index")
         .allowlist_function("rb_shape_get_next")
         .allowlist_function("rb_shape_id")
         .allowlist_function("rb_shape_transition_shape_capa")
+        .allowlist_var("SHAPE_ID_NUM_BITS")
 
         // From ruby/internal/intern/object.h
         .allowlist_function("rb_obj_is_kind_of")

yjit/src/codegen.rs

@@ -2045,9 +2045,8 @@ fn gen_get_ivar(
     let embed_test_result = unsafe { FL_TEST_RAW(comptime_receiver, VALUE(ROBJECT_EMBED.as_usize())) != VALUE(0) };
 
     let expected_shape = unsafe { rb_shape_get_shape_id(comptime_receiver) };
-    let shape_bit_size = unsafe { rb_shape_id_num_bits() }; // either 16 or 32 depending on RUBY_DEBUG
     let shape_id_offset = unsafe { rb_shape_id_offset() };
-    let shape_opnd = Opnd::mem(shape_bit_size, recv, shape_id_offset);
+    let shape_opnd = Opnd::mem(SHAPE_ID_NUM_BITS as u8, recv, shape_id_offset);
 
     asm.comment("guard shape");
     asm.cmp(shape_opnd, Opnd::UImm(expected_shape as u64));
@@ -2269,9 +2268,8 @@ fn gen_setinstancevariable(
         }
 
         let expected_shape = unsafe { rb_shape_get_shape_id(comptime_receiver) };
-        let shape_bit_size = unsafe { rb_shape_id_num_bits() }; // either 16 or 32 depending on RUBY_DEBUG
         let shape_id_offset = unsafe { rb_shape_id_offset() };
-        let shape_opnd = Opnd::mem(shape_bit_size, recv, shape_id_offset);
+        let shape_opnd = Opnd::mem(SHAPE_ID_NUM_BITS as u8, recv, shape_id_offset);
 
         asm.comment("guard shape");
         asm.cmp(shape_opnd, Opnd::UImm(expected_shape as u64));
@@ -2334,9 +2332,8 @@ fn gen_setinstancevariable(
 
                 asm.comment("write shape");
 
-                let shape_bit_size = unsafe { rb_shape_id_num_bits() }; // either 16 or 32 depending on RUBY_DEBUG
                 let shape_id_offset = unsafe { rb_shape_id_offset() };
-                let shape_opnd = Opnd::mem(shape_bit_size, recv, shape_id_offset);
+                let shape_opnd = Opnd::mem(SHAPE_ID_NUM_BITS as u8, recv, shape_id_offset);
 
                 // Store the new shape
                 asm.store(shape_opnd, Opnd::UImm(new_shape_id as u64));

yjit/src/cruby_bindings.inc.rs

@@ -123,6 +123,7 @@ impl<T> ::std::cmp::PartialEq for __BindgenUnionField<T> {
     }
 }
 impl<T> ::std::cmp::Eq for __BindgenUnionField<T> {}
+pub const SHAPE_ID_NUM_BITS: u32 = 32;
 pub const INTEGER_REDEFINED_OP_FLAG: u32 = 1;
 pub const FLOAT_REDEFINED_OP_FLAG: u32 = 2;
 pub const STRING_REDEFINED_OP_FLAG: u32 = 4;
@@ -443,9 +444,6 @@ pub struct rb_shape {
     pub parent_id: shape_id_t,
 }
 pub type rb_shape_t = rb_shape;
-extern "C" {
-    pub fn rb_shape_id_num_bits() -> u8;
-}
 extern "C" {
     pub fn rb_shape_id_offset() -> i32;
 }