Aaron Patterson 9e067df76b 32 bit comparison on shape id ... This commit changes the shape id comparisons to use a 32 bit comparison rather than 64 bit. That means we don't need to load the shape id to a register on x86 machines. Given the following program: ```ruby class Foo def initialize @foo = 1 @bar = 1 end def read [@foo, @bar] end end foo = Foo.new foo.read foo.read foo.read foo.read foo.read puts RubyVM::YJIT.disasm(Foo.instance_method(:read)) ``` The machine code we generated _before_ this change is like this: ``` == BLOCK 1/4, ISEQ RANGE [0,3), 65 bytes ====================== # getinstancevariable 0x559a18623023: mov rax, qword ptr [r13 + 0x18] # guard object is heap 0x559a18623027: test al, 7 0x559a1862302a: jne 0x559a1862502d 0x559a18623030: cmp rax, 4 0x559a18623034: jbe 0x559a1862502d # guard shape, embedded, and T_OBJECT 0x559a1862303a: mov rcx, qword ptr [rax] 0x559a1862303d: movabs r11, 0xffff00000000201f 0x559a18623047: and rcx, r11 0x559a1862304a: movabs r11, 0xb000000002001 0x559a18623054: cmp rcx, r11 0x559a18623057: jne 0x559a18625046 0x559a1862305d: mov rax, qword ptr [rax + 0x18] 0x559a18623061: mov qword ptr [rbx], rax == BLOCK 2/4, ISEQ RANGE [3,6), 0 bytes ======================= == BLOCK 3/4, ISEQ RANGE [3,6), 47 bytes ====================== # gen_direct_jmp: fallthrough # getinstancevariable # regenerate_branch # getinstancevariable # regenerate_branch 0x559a18623064: mov rax, qword ptr [r13 + 0x18] # guard shape, embedded, and T_OBJECT 0x559a18623068: mov rcx, qword ptr [rax] 0x559a1862306b: movabs r11, 0xffff00000000201f 0x559a18623075: and rcx, r11 0x559a18623078: movabs r11, 0xb000000002001 0x559a18623082: cmp rcx, r11 0x559a18623085: jne 0x559a18625099 0x559a1862308b: mov rax, qword ptr [rax + 0x20] 0x559a1862308f: mov qword ptr [rbx + 8], rax ``` After this change, it's like this: ``` == BLOCK 1/4, ISEQ RANGE [0,3), 41 bytes ====================== # getinstancevariable 0x5560c986d023: mov rax, qword ptr [r13 + 0x18] # guard object is heap 0x5560c986d027: test al, 7 0x5560c986d02a: jne 0x5560c986f02d 0x5560c986d030: cmp rax, 4 0x5560c986d034: jbe 0x5560c986f02d # guard shape 0x5560c986d03a: cmp word ptr [rax + 6], 0x19 0x5560c986d03f: jne 0x5560c986f046 0x5560c986d045: mov rax, qword ptr [rax + 0x10] 0x5560c986d049: mov qword ptr [rbx], rax == BLOCK 2/4, ISEQ RANGE [3,6), 0 bytes ======================= == BLOCK 3/4, ISEQ RANGE [3,6), 23 bytes ====================== # gen_direct_jmp: fallthrough # getinstancevariable # regenerate_branch # getinstancevariable # regenerate_branch 0x5560c986d04c: mov rax, qword ptr [r13 + 0x18] # guard shape 0x5560c986d050: cmp word ptr [rax + 6], 0x19 0x5560c986d055: jne 0x5560c986f099 0x5560c986d05b: mov rax, qword ptr [rax + 0x18] 0x5560c986d05f: mov qword ptr [rbx + 8], rax ``` The first ivar read is a bit more complex, but the second ivar read is much simpler. I think eventually we could teach the context about the shape, then emit only one shape guard.		2022-11-18 12:04:10 -08:00
..
src	32 bit comparison on shape id	2022-11-18 12:04:10 -08:00
Cargo.lock	Update bindgen crate (#6397)	2022-09-18 20:42:57 +09:00
Cargo.toml	Update bindgen crate (#6397)	2022-09-18 20:42:57 +09:00