mruby-mruby/doc/mruby3.1.md

User visible changes in mruby3.1 from mruby3.0

Build System

build_config directory

Several configurations for new platforms are added:

• cross-mingw-winetest.rb
• cross-mingw.rb
• nintendo_switch.rb
• serenity.rb

Some new configurations for added for convenience.

• minimal: minimal configuration
• host-f32: compiles with mrb_float as 32 bit float
• host-nofloat: compiles with no float configuration

And android_arm64-v8a.rb was renamed to android_arm64_v8a.rb for consistency.

Language Changes

Keyword Arguments

CRuby3.0 compatible keyword arguments are introduced. Keyword arguments are basically separated from ordinal arguments

Configuration Options Changed

Some configuration macros are available:

• MRB_WORDBOX_NO_FLOAT_TRUNCATE: by default, float values are packed in the word if possible, but define this macro to allocate float values in the heap.
• MRB_USE_RO_DATA_P_ETEXT: define this macro if _etext is available on your platform.
• MRB_NO_DEFAULT_RO_DATA_P: define this macro to avoid using predefined mrb_ro_data_p() function

Internal Changes

Reintroduced Instructions

mruby3.0 removed OP_EXT1, OP_EXT2, OP_EXT3 for operand extension. But the operand size limitations was too tight for real-world application. mruby3.1 reintroduces those extension instructions.

Removed Instructions

mruby3.1 removed following instructions.

• OP_LOADL16
• OP_LOADSYM16
• OP_STRING16
• OP_LAMBDA16
• OP_BLOCK16
• OP_METHOD16
• OP_EXEC16

Those instructions are no longer needed by reintroduction of extension instructions.

• OP_SENDV
• OP_SENDVB

Those instructions for method calls with variable number of arguments are no longer needed. They are covered by OP_SEND instruction with n=15.

New Instructions

mruby3.1 introduces following new instructions.

• OP_GETIDX: takes 2 operands a[b]
• OP_SETIDX: takes 3 operands a[b]=c
• OP_SSEND: takes 3 operands a=self.b(c...); see OP_SEND
• OP_SSENDB: takes 3 operands a=self.b(c...){...}; see OP_SEND

OP_GETIDX and OP_SETIDX

Execute obj[int] and obj[int] = value respectively, where obj is string|array|hash.

OP_SSEND and OP_SSENDB

They are similar to OP_SEND and OP_SENDB respectively. They initialize the R[a] by self first so that we can skip one OP_LOADSELF instruction for each call.

Changed Instructions

OP_SEND and OP_SENDB

Method calling instructions are unified. Now OP_SEND and OP_SENDB (method call with a block) can support both splat arguments and keyword arguments as well.

The brief description of the instructions:

|OP_SEND | BBB | R(a) = call(R(a),Syms(b),R(a+1..n),R(a+n+1),R(a+n+2)..nk) c=n|nk<<4 | |OP_SENDB | BBB | R(a) = call(R(a),Syms(b),R(a+1..n),R(a+n+1..nk),R(a+n+2..nk),&R(a+n+2*nk+2)) c=n|nk<<4 |

When n == 15, the method takes arguments packed in an array. When nk == 15, the method takes keyword arguments packed in a hash.

OP_ARYPUSH

Now takes 2 operands and pushes multiple entries to an array.

String#hash now use FNV1a algorithm

For better and faster hash values.