Specialize String#byteslice(a, b) (#9939)

* Specialize String#byteslice(a, b)

This adds a specialization for String#byteslice when there are two
parameters.

This makes our protobuf parser go from 5.84x slower to 5.33x slower

```
Comparison:
decode upstream (53738 bytes):     7228.5 i/s
decode protobuff (53738 bytes):     1236.8 i/s - 5.84x  slower

Comparison:
decode upstream (53738 bytes):     7024.8 i/s
decode protobuff (53738 bytes):     1318.5 i/s - 5.33x  slower
```

* Update yjit/src/codegen.rs

---------

Co-authored-by: Maxime Chevalier-Boisvert <maximechevalierb@gmail.com>

internal/string.h

@@ -45,6 +45,7 @@ void rb_str_make_independent(VALUE str);
 int rb_enc_str_coderange_scan(VALUE str, rb_encoding *enc);
 int rb_ascii8bit_appendable_encoding_index(rb_encoding *enc, unsigned int code);
 VALUE rb_str_include(VALUE str, VALUE arg);
+VALUE rb_str_byte_substr(VALUE str, VALUE beg, VALUE len);
 
 static inline bool STR_EMBED_P(VALUE str);
 static inline bool STR_SHARED_P(VALUE str);

string.c

@@ -6274,6 +6274,12 @@ str_byte_substr(VALUE str, long beg, long len, int empty)
     return str2;
 }
 
+VALUE
+rb_str_byte_substr(VALUE str, VALUE beg, VALUE len)
+{
+    return str_byte_substr(str, NUM2LONG(beg), NUM2LONG(len), TRUE);
+}
+
 static VALUE
 str_byte_aref(VALUE str, VALUE indx)
 {

yjit/bindgen/src/main.rs

@@ -224,6 +224,7 @@ fn main() {
         .allowlist_function("rb_ec_str_resurrect")
         .allowlist_function("rb_str_concat_literals")
         .allowlist_function("rb_obj_as_string_result")
+        .allowlist_function("rb_str_byte_substr")
 
         // From include/ruby/internal/intern/parse.h
         .allowlist_function("rb_backref_get")

yjit/src/codegen.rs

@@ -5304,6 +5304,37 @@ fn jit_rb_str_bytesize(
     true
 }
 
+fn jit_rb_str_byteslice(
+    jit: &mut JITState,
+    asm: &mut Assembler,
+    _ocb: &mut OutlinedCb,
+    _ci: *const rb_callinfo,
+    _cme: *const rb_callable_method_entry_t,
+    _block: Option<BlockHandler>,
+    argc: i32,
+    _known_recv_class: Option<VALUE>,
+) -> bool {
+    asm_comment!(asm, "String#byteslice");
+
+    if argc != 2 {
+        return false
+    }
+
+    // Raises when non-integers are passed in
+    jit_prepare_non_leaf_call(jit, asm);
+
+    let len = asm.stack_opnd(0);
+    let beg = asm.stack_opnd(1);
+    let recv = asm.stack_opnd(2);
+    let ret_opnd = asm.ccall(rb_str_byte_substr as *const u8, vec![recv, beg, len]);
+    asm.stack_pop(3);
+
+    let out_opnd = asm.stack_push(Type::TString);
+    asm.mov(out_opnd, ret_opnd);
+
+    true
+}
+
 fn jit_rb_str_getbyte(
     jit: &mut JITState,
     asm: &mut Assembler,
@@ -9490,6 +9521,7 @@ pub fn yjit_reg_method_codegen_fns() {
         yjit_reg_method(rb_cString, "size", jit_rb_str_length);
         yjit_reg_method(rb_cString, "bytesize", jit_rb_str_bytesize);
         yjit_reg_method(rb_cString, "getbyte", jit_rb_str_getbyte);
+        yjit_reg_method(rb_cString, "byteslice", jit_rb_str_byteslice);
         yjit_reg_method(rb_cString, "<<", jit_rb_str_concat);
         yjit_reg_method(rb_cString, "+@", jit_rb_str_uplus);
 

yjit/src/cruby_bindings.inc.rs

@@ -1049,6 +1049,7 @@ extern "C" {
     pub fn rb_gvar_set(arg1: ID, arg2: VALUE) -> VALUE;
     pub fn rb_ensure_iv_list_size(obj: VALUE, len: u32, newsize: u32);
     pub fn rb_vm_barrier();
+    pub fn rb_str_byte_substr(str_: VALUE, beg: VALUE, len: VALUE) -> VALUE;
     pub fn rb_obj_as_string_result(str_: VALUE, obj: VALUE) -> VALUE;
     pub fn rb_str_concat_literals(num: usize, strary: *const VALUE) -> VALUE;
     pub fn rb_ec_str_resurrect(ec: *mut rb_execution_context_struct, str_: VALUE) -> VALUE;