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2021-12-03YJIT: Bounds check every byte in the assemblerAlan Wu
Previously, YJIT assumed that basic blocks never consume more than 1 KiB of memory. This assumption does not hold for long Ruby methods such as the one in the following: ```ruby eval(<<RUBY) def set_local_a_lot #{'_=0;'*0x40000} end RUBY set_local_a_lot ``` For low `--yjit-exec-mem-size` values, one basic block could exhaust the entire buffer. Introduce a new field `codeblock_t::dropped_bytes` that the assembler sets whenever it runs out of space. Check this field in gen_single_block() to respond to out of memory situations and other error conditions. This design avoids making the control flow graph of existing code generation functions more complex. Use POSIX shell in misc/test_yjit_asm.sh since bash is expanding `0%/*/*` differently. Co-authored-by: Aaron Patterson <tenderlove@ruby-lang.org> Notes: Merged: https://github.com/ruby/ruby/pull/5209
2021-12-01Mark JIT code as writeable / executable depending on the situationAaron Patterson
Some platforms don't want memory to be marked as writeable and executable at the same time. When we write to the code block, we calculate the OS page that the buffer position maps to. Then we call `mprotect` to allow writes on that particular page. As an optimization, we cache the "last written" aligned page which allows us to amortize the cost of the `mprotect` call. In other words, sequential writes to the same page will only call `mprotect` on the page once. When we're done writing, we call `mprotect` on the entire JIT buffer. This means we don't need to keep track of which pages were marked as writeable, we let the OS take care of that. Co-authored-by: John Hawthorn <john@hawthorn.email> Notes: Merged: https://github.com/ruby/ruby/pull/5032
2021-11-05YJIT: use shorter encoding for mov(r64,imm) when unambiguous (#5081)Alan Wu
* YJIT: use shorter encoding for mov(r64,imm) when unambiguous Previously, for small constants such as `mov(RAX, imm_opnd(Qundef))`, we emit an instruction with an 8-byte immediate. This form commonly gets the `movabs` mnemonic. In 64-bit mode, 32-bit operands get zero extended to 64-bit to fill the register, so when the immediate is small enough, we can save 4 bytes by using the `mov` variant that takes a 32-bit immediate and does a zero extension. Not implement with this change, there is an imm32 variant of `mov` that does sign extension we could use. When the constant is negative, we fallback to the `movabs` form. In railsbench, this change yields roughly a 12% code size reduction for the outlined block. Co-authored-by: Jemma Issroff <jemmaissroff@gmail.com> * [ci skip] comment edit. Please squash. Co-authored-by: Jemma Issroff <jemmaissroff@gmail.com> Notes: Merged-By: maximecb <maximecb@ruby-lang.org>
2021-11-04YJIT code pages refactoring for code GC (#5073)Maxime Chevalier-Boisvert
* New code page allocation logic * Fix leaked globals * Fix leaked symbols, yjit asm tests * Make COUNTED_EXIT take a jit argument, so we can eliminate global ocb * Remove extra whitespace * Change block start_pos/end_pos to be pointers instead of uint32_t * Change branch end_pos and start_pos to end_addr, start_addr Notes: Merged-By: maximecb <maximecb@ruby-lang.org>
2021-10-27Fix yjit_asm_tests.c as C99 compliant (#5033)Nobuyoshi Nakada
* rb_bug should be variadic * Prefer ANSI-style prototypes over old K&R-style definitions * Add missing argument types Notes: Merged-By: maximecb <maximecb@ruby-lang.org>
2021-10-21Move the test fileNobuyoshi Nakada