MJIT: Use a String buffer in builtin compilers

instead of FILE*.

Using C.fprintf is slower than String manipulation on memory. I'm going
to change the way MJIT writes files, and this is a prerequisite for it.

builtin.h

@@ -13,7 +13,7 @@ struct rb_builtin_function {
     const char * const name;
 
     // for jit
-    void (*compiler)(FILE *, long, unsigned, bool);
+    void (*compiler)(VALUE, long, unsigned, bool);
 };
 
 #define RB_BUILTIN_FUNCTION(_i, _name, _fname, _arity, _compiler) {\

lib/mjit/compiler.rb

@@ -203,8 +203,8 @@ module RubyVM::MJIT
           return src, next_pos, finish_p, compile_insns
         end
       when :invokebuiltin, :opt_invokebuiltin_delegate
-        if compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+        if src = compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
-          return '', next_pos, finish_p, compile_insns
+          return src, next_pos, finish_p, compile_insns
         end
       when :opt_getconstant_path
         if src = compile_getconstant_path(stack_size, pos, insn_len, operands, status)
@@ -215,7 +215,9 @@ module RubyVM::MJIT
 
         # opt_invokebuiltin_delegate_leave also implements leave insn. We need to handle it here for inlining.
         if insn.name == :opt_invokebuiltin_delegate_leave
-          compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+          if invokebuiltin_src = compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
+            src << invokebuiltin_src
+          end
         else
           if stack_size != 1
             $stderr.puts "MJIT warning: Unexpected JIT stack_size on leave: #{stack_size}" # TODO: check mjit_opts?
@@ -407,18 +409,18 @@ module RubyVM::MJIT
       end
     end
 
-    def compile_invokebuiltin(f, insn, stack_size, sp_inc, body, operands)
+    def compile_invokebuiltin(insn, stack_size, sp_inc, body, operands)
       bf = C.RB_BUILTIN.new(operands[0])
       if bf.compiler > 0
         index = (insn.name == :invokebuiltin ? -1 : operands[1])
-        C.fprintf(f, "{\n")
+        src = +"{\n"
-        C.fprintf(f, "    VALUE val;\n")
+        src << "    VALUE val;\n"
-        C.builtin_compiler(f, bf, index, stack_size, body.builtin_inline_p)
+        C.builtin_compiler(src, bf, index, stack_size, body.builtin_inline_p)
-        C.fprintf(f, "    stack[#{stack_size + sp_inc - 1}] = val;\n")
+        src << "    stack[#{stack_size + sp_inc - 1}] = val;\n"
-        C.fprintf(f, "}\n")
+        src << "}\n"
-        return true
+        return src
       else
-        return false
+        return nil
       end
     end
 

mjit_compiler.c

@@ -143,11 +143,11 @@ cdhash_to_hash(rb_execution_context_t *ec, VALUE self, VALUE cdhash_addr)
 }
 
 static VALUE
-builtin_compile(rb_execution_context_t *ec, VALUE self, VALUE f_addr, VALUE bf_addr, VALUE index, VALUE stack_size, VALUE builtin_inline_p)
+builtin_compile(rb_execution_context_t *ec, VALUE self, VALUE buf, VALUE bf_addr, VALUE index, VALUE stack_size, VALUE builtin_inline_p)
 {
-    FILE *f = (FILE *)NUM2PTR(f_addr);
+    // Call "mjit_compile_invokebuiltin_for_#{func}" in mk_builtin_loader.rb
     RB_BUILTIN bf = (RB_BUILTIN)NUM2PTR(bf_addr);
-    bf->compiler(f, NIL_P(index) ? -1 : NUM2LONG(index), NUM2UINT(stack_size), RTEST(builtin_inline_p));
+    bf->compiler(buf, NIL_P(index) ? -1 : NUM2LONG(index), NUM2UINT(stack_size), RTEST(builtin_inline_p));
     return Qnil;
 }
 

tool/mk_builtin_loader.rb

@@ -325,10 +325,10 @@ def mk_builtin_header file
            . map {|i|", argv[#{i}]"} \
            . join('')
       f.puts %'static void'
-      f.puts %'mjit_compile_invokebuiltin_for_#{func}(FILE *f, long index, unsigned stack_size, bool inlinable_p)'
+      f.puts %'mjit_compile_invokebuiltin_for_#{func}(VALUE buf, long index, unsigned stack_size, bool inlinable_p)'
       f.puts %'{'
-      f.puts %'    fprintf(f, "    VALUE self = GET_SELF();\\n");'
+      f.puts %'    rb_str_catf(buf, "    VALUE self = GET_SELF();\\n");'
-      f.puts %'    fprintf(f, "    typedef VALUE (*func)(rb_execution_context_t *, VALUE#{decl});\\n");'
+      f.puts %'    rb_str_catf(buf, "    typedef VALUE (*func)(rb_execution_context_t *, VALUE#{decl});\\n");'
       if inlines.has_key? cfunc_name
         body_lineno, text, locals, func_name = inlines[cfunc_name]
         lineno, str = generate_cexpr(ofile, lineno, line_file, body_lineno, text, locals, func_name)
@@ -336,22 +336,22 @@ def mk_builtin_header file
         str.gsub(/^(?!#)/, '    ').each_line {|i|
           j = RubyVM::CEscape.rstring2cstr(i).dup
           j.sub!(/^    return\b/ , '    val =')
-          f.printf(%'        fprintf(f, "%%s", %s);\n', j)
+          f.printf(%'        rb_str_catf(buf, "%%s", %s);\n', j)
         }
         f.puts(%'        return;')
         f.puts(%'    }')
       end
       if argc > 0
         f.puts %'    if (index == -1) {'
-        f.puts %'        fprintf(f, "    const VALUE *argv = &stack[%d];\\n", stack_size - #{argc});'
+        f.puts %'        rb_str_catf(buf, "    const VALUE *argv = &stack[%d];\\n", stack_size - #{argc});'
         f.puts %'    }'
         f.puts %'    else {'
-        f.puts %'        fprintf(f, "    const unsigned int lnum = ISEQ_BODY(GET_ISEQ())->local_table_size;\\n");'
+        f.puts %'        rb_str_catf(buf, "    const unsigned int lnum = ISEQ_BODY(GET_ISEQ())->local_table_size;\\n");'
-        f.puts %'        fprintf(f, "    const VALUE *argv = GET_EP() - lnum - VM_ENV_DATA_SIZE + 1 + %ld;\\n", index);'
+        f.puts %'        rb_str_catf(buf, "    const VALUE *argv = GET_EP() - lnum - VM_ENV_DATA_SIZE + 1 + %ld;\\n", index);'
         f.puts %'    }'
       end
-      f.puts %'    fprintf(f, "    func f = (func)%"PRIuVALUE"; /* == #{cfunc_name} */\\n", (VALUE)#{cfunc_name});'
+      f.puts %'    rb_str_catf(buf, "    func f = (func)%"PRIuVALUE"; /* == #{cfunc_name} */\\n", (VALUE)#{cfunc_name});'
-      f.puts %'    fprintf(f, "    val = f(ec, self#{argv});\\n");'
+      f.puts %'    rb_str_catf(buf, "    val = f(ec, self#{argv});\\n");'
       f.puts %'}'
       f.puts
     }

yjit/src/cruby.rs

@@ -270,13 +270,6 @@ pub struct rb_method_cfunc_t {
     _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
 }
 
-/// Opaque FILE type from the C standard library
-#[repr(C)]
-pub struct FILE {
-    _data: [u8; 0],
-    _marker: core::marker::PhantomData<(*mut u8, core::marker::PhantomPinned)>,
-}
-
 /// Opaque call-cache type from vm_callinfo.h
 #[repr(C)]
 pub struct rb_callcache {

yjit/src/cruby_bindings.inc.rs

@@ -1047,7 +1047,7 @@ pub struct rb_builtin_function {
     pub name: *const ::std::os::raw::c_char,
     pub compiler: ::std::option::Option<
         unsafe extern "C" fn(
-            arg1: *mut FILE,
+            arg1: VALUE,
             arg2: ::std::os::raw::c_long,
             arg3: ::std::os::raw::c_uint,
             arg4: bool,