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make some jit parameters configurable at runtime

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This commit is contained in:
Fabian 2022-11-23 10:53:26 -06:00
parent 14b72530d4
commit af1cb6d17d
3 changed files with 46 additions and 29 deletions
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6
src/browser/print_stats.js
View file

@ -152,9 +152,9 @@ const print_stats = {
text += "wasm memory size: " + (cpu.wasm_memory.buffer.byteLength >> 20) + "m\n";
text += "Config:\n";
text += "MAX_PAGES=" + cpu.wm.exports["get_config"](0) + "\n";
text += "JIT_USE_LOOP_SAFETY=" + cpu.wm.exports["get_config"](1) + "\n";
text += "MAX_EXTRA_BASIC_BLOCKS=" + cpu.wm.exports["get_config"](2) + "\n";
text += "MAX_PAGES=" + cpu.wm.exports["get_jit_config"](0) + "\n";
text += "JIT_USE_LOOP_SAFETY=" + Boolean(cpu.wm.exports["get_jit_config"](1)) + "\n";
text += "MAX_EXTRA_BASIC_BLOCKS=" + cpu.wm.exports["get_jit_config"](2) + "\n";
return text;
},

4
src/rust/control_flow.rs
View file

@ -276,7 +276,9 @@ pub fn loopify(nodes: &Graph) -> Vec<WasmStructure> {
//);
}
if entries_to_group.len() * group.len() > MAX_EXTRA_BASIC_BLOCKS {
let max_extra_basic_blocks = unsafe { MAX_EXTRA_BASIC_BLOCKS } as usize;
if entries_to_group.len() * group.len() > max_extra_basic_blocks {
let mut subgroup_edges: Graph = Graph::new();
for elem in group {
subgroup_edges.insert(

65
src/rust/jit.rs
View file

@ -56,18 +56,27 @@ pub fn jit_clear_func(wasm_table_index: WasmTableIndex) {
unsafe { unsafe_jit::jit_clear_func(wasm_table_index) }
}
// less branches will generate if-else, more will generate brtable
pub const BRTABLE_CUTOFF: usize = 10;
// Maximum number of pages per wasm module. Necessary for the following reasons:
// - There is an upper limit on the size of a single function in wasm (currently ~7MB in all browsers)
// See https://github.com/WebAssembly/design/issues/1138
// - v8 poorly handles large br_table elements and OOMs on modules much smaller than the above limit
// See https://bugs.chromium.org/p/v8/issues/detail?id=9697 and https://bugs.chromium.org/p/v8/issues/detail?id=9141
// Will hopefully be fixed in the near future by generating direct control flow
static mut MAX_PAGES: u32 = 3;
pub const WASM_TABLE_SIZE: u32 = 900;
static mut JIT_USE_LOOP_SAFETY: bool = true;
pub const CHECK_JIT_STATE_INVARIANTS: bool = false;
pub const JIT_USE_LOOP_SAFETY: bool = true;
pub static mut MAX_EXTRA_BASIC_BLOCKS: u32 = 250;
pub const JIT_THRESHOLD: u32 = 200 * 1000;
pub const MAX_EXTRA_BASIC_BLOCKS: usize = 250;
// less branches will generate if-else, more will generate brtable
pub const BRTABLE_CUTOFF: usize = 10;
// needs to be synced to const.js
pub const WASM_TABLE_SIZE: u32 = 900;
pub const CHECK_JIT_STATE_INVARIANTS: bool = false;
const MAX_INSTRUCTION_LENGTH: u32 = 16;
@ -372,14 +381,6 @@ pub fn jit_find_cache_entry_in_page(
return -1;
}
// Maximum number of pages per wasm module. Necessary for the following reasons:
// - There is an upper limit on the size of a single function in wasm (currently ~7MB in all browsers)
// See https://github.com/WebAssembly/design/issues/1138
// - v8 poorly handles large br_table elements and OOMs on modules much smaller than the above limit
// See https://bugs.chromium.org/p/v8/issues/detail?id=9697 and https://bugs.chromium.org/p/v8/issues/detail?id=9141
// Will hopefully be fixed in the near future by generating direct control flow
const MAX_PAGES: usize = 3;
fn jit_find_basic_blocks(
ctx: &mut JitState,
entry_points: HashSet<i32>,
@ -390,7 +391,7 @@ fn jit_find_basic_blocks(
ctx: &mut JitState,
pages: &mut HashSet<Page>,
page_blacklist: &mut HashSet<Page>,
max_pages: usize,
max_pages: u32,
marked_as_entry: &mut HashSet<i32>,
to_visit_stack: &mut Vec<i32>,
) -> Option<u32> {
@ -407,7 +408,7 @@ fn jit_find_basic_blocks(
let phys_page = Page::page_of(phys_target);
if !pages.contains(&phys_page) && pages.len() == max_pages
if !pages.contains(&phys_page) && pages.len() as u32 == max_pages
|| page_blacklist.contains(&phys_page)
{
return None;
@ -453,7 +454,7 @@ fn jit_find_basic_blocks(
}
pages.insert(phys_page);
dbg_assert!(pages.len() <= max_pages);
dbg_assert!(pages.len() as u32 <= max_pages);
}
to_visit_stack.push(virt_target);
@ -467,7 +468,12 @@ fn jit_find_basic_blocks(
let mut page_blacklist = HashSet::new();
// 16-bit doesn't not work correctly, most likely due to instruction pointer wrap-around
let max_pages = if cpu.state_flags.is_32() { MAX_PAGES } else { 1 };
let max_pages = if cpu.state_flags.is_32() {
unsafe { MAX_PAGES }
}
else {
1
};
for virt_addr in entry_points {
let ok = follow_jump(
@ -712,7 +718,7 @@ fn jit_find_basic_blocks(
basic_blocks.insert(current_block.addr, current_block);
}
dbg_assert!(pages.len() <= max_pages);
dbg_assert!(pages.len() as u32 <= max_pages);
for block in basic_blocks.values_mut() {
if marked_as_entry.contains(&block.virt_addr) {
@ -935,7 +941,7 @@ fn jit_analyze_and_generate(
dbg_assert!(wasm_table_index != WasmTableIndex(0));
dbg_assert!(!pages.is_empty());
dbg_assert!(pages.len() <= MAX_PAGES);
dbg_assert!(pages.len() <= unsafe { MAX_PAGES } as usize);
let basic_block_by_addr: HashMap<u32, BasicBlock> =
basic_blocks.into_iter().map(|b| (b.addr, b)).collect();
@ -1152,7 +1158,7 @@ fn jit_generate_module(
let exit_label = builder.block_void();
let exit_with_fault_label = builder.block_void();
let main_loop_label = builder.loop_void();
if JIT_USE_LOOP_SAFETY {
if unsafe { JIT_USE_LOOP_SAFETY } {
builder.get_local(&instruction_counter);
builder.const_i32(cpu::LOOP_COUNTER);
builder.geu_i32();
@ -1822,7 +1828,7 @@ fn jit_generate_module(
codegen::gen_set_eip_low_bits(ctx.builder, addr as i32 & 0xFFF);
profiler::stat_increment(stat::COMPILE_WITH_LOOP_SAFETY);
codegen::gen_profiler_stat_increment(ctx.builder, stat::LOOP_SAFETY);
if JIT_USE_LOOP_SAFETY {
if unsafe { JIT_USE_LOOP_SAFETY } {
ctx.builder.get_local(&ctx.instruction_counter);
ctx.builder.const_i32(cpu::LOOP_COUNTER);
ctx.builder.geu_i32();
@ -2393,8 +2399,17 @@ pub fn enter_basic_block(phys_eip: u32) {
}
#[no_mangle]
#[cfg(feature = "profiler")]
pub fn get_config(index: u32) -> u32 {
pub unsafe fn set_jit_config(index: u32, value: u32) {
match index {
0 => MAX_PAGES = value,
1 => JIT_USE_LOOP_SAFETY = value != 0,
2 => MAX_EXTRA_BASIC_BLOCKS = value,
_ => dbg_assert!(false),
}
}
#[no_mangle]
pub unsafe fn get_jit_config(index: u32) -> u32 {
match index {
0 => MAX_PAGES as u32,
1 => JIT_USE_LOOP_SAFETY as u32,