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Move loop safety back to beginning of loop

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This commit is contained in:
Fabian 2020-12-31 19:14:33 -06:00
parent 06f656ffdd
commit 3e18e05272
3 changed files with 32 additions and 77 deletions
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3
src/browser/print_stats.js
View file

@ -60,6 +60,7 @@ const print_stats = {
"DISPATCHER_SMALL",
"DISPATCHER_LARGE",
"LOOP",
"LOOP_SAFETY",
"CONDITION_OPTIMISED",
"CONDITION_UNOPTIMISED",
"FAILED_PAGE_CHANGE",
@ -145,7 +146,7 @@ const print_stats = {
text += "Config:\n";
text += "MAX_PAGES=" + cpu.wm.exports["get_config"](0) + "\n";
text += "JIT_ALWAYS_USE_LOOP_SAFETY=" + cpu.wm.exports["get_config"](1) + "\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";
return text;

104
src/rust/jit.rs
View file

@ -66,7 +66,7 @@ pub const CHECK_JIT_STATE_INVARIANTS: bool = false;
pub const JIT_MAX_ITERATIONS_PER_FUNCTION: u32 = 100003;
pub const JIT_ALWAYS_USE_LOOP_SAFETY: bool = true;
pub const JIT_USE_LOOP_SAFETY: bool = true;
pub const JIT_THRESHOLD: u32 = 200 * 1000;
@ -1007,7 +1007,7 @@ fn jit_generate_module(
})
.collect();
let loop_limit_local = if JIT_ALWAYS_USE_LOOP_SAFETY {
let loop_limit_local = if JIT_USE_LOOP_SAFETY {
builder.const_i32(JIT_MAX_ITERATIONS_PER_FUNCTION as i32);
Some(builder.set_new_local())
}
@ -1244,35 +1244,6 @@ fn jit_generate_module(
next_block_addr,
);
}
else if next_block_addr == block.addr {
// for qnx: Heuristic to terminated endless loops
codegen::gen_set_eip_low_bits(
ctx.builder,
block.end_addr as i32 & 0xFFF,
);
if jump_offset_is_32 {
codegen::gen_relative_jump(ctx.builder, jump_offset);
}
else {
codegen::gen_jmp_rel16(ctx.builder, jump_offset as u16);
}
if let Some(loop_limit_local) = loop_limit_local.as_ref() {
ctx.builder.get_local(loop_limit_local);
ctx.builder.const_i32(-1);
ctx.builder.add_i32();
ctx.builder.tee_local(loop_limit_local);
ctx.builder.eqz_i32();
if cfg!(feature = "profiler") {
ctx.builder.if_void();
codegen::gen_debug_track_jit_exit(ctx.builder, 0);
ctx.builder.br(ctx.exit_label);
ctx.builder.block_end();
}
else {
ctx.builder.br_if(ctx.exit_label);
}
}
}
if next_addr
.as_ref()
@ -1376,37 +1347,6 @@ fn jit_generate_module(
next_block_branch_taken_addr,
);
}
else if next_block_branch_taken_addr <= block.addr {
// heuristic to terminate "delay loops" etc
// for Linux 2.x and 3.x, oberon, windows 95
codegen::gen_set_eip_low_bits(
ctx.builder,
block.end_addr as i32 & 0xFFF,
);
if jump_offset_is_32 {
codegen::gen_relative_jump(ctx.builder, jump_offset);
}
else {
codegen::gen_jmp_rel16(ctx.builder, jump_offset as u16);
}
if let Some(loop_limit_local) = loop_limit_local.as_ref() {
ctx.builder.get_local(loop_limit_local);
ctx.builder.const_i32(-1);
ctx.builder.add_i32();
ctx.builder.tee_local(loop_limit_local);
ctx.builder.eqz_i32();
if cfg!(feature = "profiler") {
ctx.builder.if_void();
codegen::gen_debug_track_jit_exit(ctx.builder, 0);
ctx.builder.br(ctx.exit_label);
ctx.builder.block_end();
}
else {
ctx.builder.br_if(ctx.exit_label);
}
}
}
if next_addr
.as_ref()
@ -1612,10 +1552,33 @@ fn jit_generate_module(
},
Work::WasmStructure(WasmStructure::Loop(children)) => {
profiler::stat_increment(stat::COMPILE_WASM_LOOP);
codegen::gen_profiler_stat_increment(ctx.builder, stat::LOOP);
let entries: Vec<u32> = children[0].head().collect();
let label = ctx.builder.loop_void();
codegen::gen_profiler_stat_increment(ctx.builder, stat::LOOP);
if entries.len() == 1 {
let addr = entries[0];
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 let Some(loop_limit_local) = loop_limit_local.as_ref() {
ctx.builder.get_local(loop_limit_local);
ctx.builder.const_i32(-1);
ctx.builder.add_i32();
ctx.builder.tee_local(loop_limit_local);
ctx.builder.eqz_i32();
if cfg!(feature = "profiler") {
ctx.builder.if_void();
codegen::gen_debug_track_jit_exit(ctx.builder, 0);
ctx.builder.br(ctx.exit_label);
ctx.builder.block_end();
}
else {
ctx.builder.br_if(ctx.exit_label);
}
}
}
let mut olds = HashMap::new();
for &target in entries.iter() {
@ -1772,10 +1735,6 @@ fn jit_generate_module(
}
fn jit_generate_basic_block(ctx: &mut JitContext, block: &BasicBlock) {
let needs_previous_ip_updated = match block.ty {
BasicBlockType::Exit => true,
_ => false,
};
let needs_eip_updated = match block.ty {
BasicBlockType::Exit => true,
_ => false,
@ -1811,20 +1770,13 @@ fn jit_generate_basic_block(ctx: &mut JitContext, block: &BasicBlock) {
// Before the last instruction:
// - Set eip to *after* the instruction
// - Set previous_eip to *before* the instruction
if needs_previous_ip_updated {
//codegen::gen_set_previous_eip_offset_from_eip(
// ctx.builder,
// last_instruction_addr - start_addr,
//);
if needs_eip_updated {
codegen::gen_set_previous_eip_offset_from_eip_with_low_bits(
ctx.builder,
last_instruction_addr as i32 & 0xFFF,
);
}
if needs_eip_updated {
codegen::gen_set_eip_low_bits(ctx.builder, stop_addr as i32 & 0xFFF);
}
//codegen::gen_relative_jump(ctx.builder, (stop_addr - start_addr) as i32);
}
else {
ctx.last_instruction = Instruction::Other;
@ -2181,7 +2133,7 @@ pub fn enter_basic_block(phys_eip: u32) {
pub fn get_config(index: u32) -> u32 {
match index {
0 => MAX_PAGES as u32,
1 => JIT_ALWAYS_USE_LOOP_SAFETY as u32,
1 => JIT_USE_LOOP_SAFETY as u32,
2 => MAX_EXTRA_BASIC_BLOCKS as u32,
_ => 0,
}

2
src/rust/profiler.rs
View file

@ -49,6 +49,8 @@ pub enum stat {
DISPATCHER_LARGE,
LOOP,
LOOP_SAFETY,
CONDITION_OPTIMISED,
CONDITION_UNOPTIMISED,