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clif-backend: Eliminate FunctionEnvironment construction in feed_event()

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The feed_event() function is called for every wasm binary instruction.
Let's optimize it by storing FunctionEnvironment object in
CraneliftFunctionCodeGenerator, rather than constructing it for every
feed_event() invocation.

This change reduces the time to run "ngix compile" benchmark by 68%:

Before:

  nginx compile           time:   [1.4152 s 1.4186 s 1.4222 s]
  Found 1 outliers among 10 measurements (10.00%)
    1 (10.00%) high mild

After:

  nginx compile           time:   [447.76 ms 448.32 ms 448.80 ms]
                          change: [-68.542% -68.440% -68.352%] (p = 0.00 < 0.05)
                          Performance has improved.

I assume some of the clone() calls are very expensive (Vec::clone(),
likely). I did see libc malloc()/free() high up in "perf top" profiles,
which are eliminted by this change.

I also looked into eliminating FunctionBuilder construction from
feed_event(). That turns out to be painful on lifetime rules because it
borrows bunch of other objects, so I am leaving it for someone who knows
the code better than I do.
This commit is contained in:
Pekka Enberg 2019-08-01 18:06:40 +03:00
parent b5e20e508d
commit 869ac21f7b
1 changed files with 7 additions and 10 deletions
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17
lib/clif-backend/src/code.rs
View File

@ -89,10 +89,13 @@ impl ModuleCodeGenerator<CraneliftFunctionCodeGenerator, Caller, CodegenError>
func,
func_translator,
next_local: 0,
clif_signatures: self.clif_signatures.clone(),
module_info: Arc::clone(&module_info),
target_config: self.isa.frontend_config().clone(),
position: Position::default(),
func_env: FunctionEnvironment {
module_info: Arc::clone(&module_info),
target_config: self.isa.frontend_config().clone(),
clif_signatures: self.clif_signatures.clone(),
},
};
debug_assert_eq!(func_env.func.dfg.num_ebbs(), 0, "Function must be empty");
@ -391,10 +394,9 @@ pub struct CraneliftFunctionCodeGenerator {
func: Function,
func_translator: FuncTranslator,
next_local: usize,
pub clif_signatures: Map<SigIndex, ir::Signature>,
module_info: Arc<RwLock<ModuleInfo>>,
target_config: isa::TargetFrontendConfig,
position: Position,
func_env: FunctionEnvironment,
}
pub struct FunctionEnvironment {
@ -1138,11 +1140,6 @@ impl FunctionCodeGenerator<CodegenError> for CraneliftFunctionCodeGenerator {
//let builder = self.builder.as_mut().unwrap();
//let func_environment = FuncEnv::new();
//let state = TranslationState::new();
let mut function_environment = FunctionEnvironment {
module_info: Arc::clone(&self.module_info),
target_config: self.target_config.clone(),
clif_signatures: self.clif_signatures.clone(),
};
if self.func_translator.state.control_stack.is_empty() {
return Ok(());
@ -1154,7 +1151,7 @@ impl FunctionCodeGenerator<CodegenError> for CraneliftFunctionCodeGenerator {
&mut self.position,
);
let state = &mut self.func_translator.state;
translate_operator(op, &mut builder, state, &mut function_environment)?;
translate_operator(op, &mut builder, state, &mut self.func_env)?;
Ok(())
}