bjoernager/rust
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Add flags customizing behaviour of MIR inlining

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* `-Zinline-mir-threshold` to change the default threshold.
* `-Zinline-mir-hint-threshold` to change the threshold used by
  functions with inline hint.
This commit is contained in:
Tomasz Miąsko 2020-11-10 00:00:00 +00:00
parent cf9cf7c923
commit c8943c62f7
5 changed files with 86 additions and 4 deletions
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2
compiler/rustc_interface/src/tests.rs
View file

@ -554,6 +554,8 @@ fn test_debugging_options_tracking_hash() {
tracked!(function_sections, Some(false));
tracked!(human_readable_cgu_names, true);
tracked!(inline_in_all_cgus, Some(true));
tracked!(inline_mir_threshold, 123);
tracked!(inline_mir_hint_threshold, 123);
tracked!(insert_sideeffect, true);
tracked!(instrument_coverage, true);
tracked!(instrument_mcount, true);

9
compiler/rustc_mir/src/transform/inline.rs
View file

@ -16,9 +16,6 @@ use crate::transform::MirPass;
use std::iter;
use std::ops::{Range, RangeFrom};
const DEFAULT_THRESHOLD: usize = 50;
const HINT_THRESHOLD: usize = 100;
const INSTR_COST: usize = 5;
const CALL_PENALTY: usize = 25;
const LANDINGPAD_PENALTY: usize = 50;
@ -248,7 +245,11 @@ impl Inliner<'tcx> {
}
}
let mut threshold = if hinted { HINT_THRESHOLD } else { DEFAULT_THRESHOLD };
let mut threshold = if hinted {
self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold
} else {
self.tcx.sess.opts.debugging_opts.inline_mir_threshold
};
// Significantly lower the threshold for inlining cold functions
if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {

4
compiler/rustc_session/src/options.rs
View file

@ -929,6 +929,10 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
(default: no)"),
incremental_verify_ich: bool = (false, parse_bool, [UNTRACKED],
"verify incr. comp. hashes of green query instances (default: no)"),
inline_mir_threshold: usize = (50, parse_uint, [TRACKED],
"a default MIR inlining threshold (default: 50)"),
inline_mir_hint_threshold: usize = (100, parse_uint, [TRACKED],
"inlining threshold for functions with inline hint (default: 100)"),
inline_in_all_cgus: Option<bool> = (None, parse_opt_bool, [TRACKED],
"control whether `#[inline]` functions are in all CGUs"),
input_stats: bool = (false, parse_bool, [UNTRACKED],

19
src/test/mir-opt/inline/inline-options.rs Normal file
View file

@ -0,0 +1,19 @@
// Checks that inlining threshold can be controlled with
// inline-mir-threshold and inline-hint-threshold options.
//
// compile-flags: -Zinline-mir-threshold=90
// compile-flags: -Zinline-mir-hint-threshold=50
// EMIT_MIR inline_options.main.Inline.after.mir
fn main() {
not_inlined();
inlined::<u32>();
}
// Cost is approximately 3 * 25 + 5 = 80.
#[inline]
pub fn not_inlined() { g(); g(); g(); }
pub fn inlined<T>() { g(); g(); g(); }
#[inline(never)]
fn g() {}

56
src/test/mir-opt/inline/inline_options.main.Inline.after.mir Normal file
View file

@ -0,0 +1,56 @@
// MIR for `main` after Inline
fn main() -> () {
let mut _0: (); // return place in scope 0 at $DIR/inline-options.rs:8:11: 8:11
let _1: (); // in scope 0 at $DIR/inline-options.rs:9:5: 9:18
let _2: (); // in scope 0 at $DIR/inline-options.rs:10:5: 10:21
scope 1 (inlined inlined::<u32>) { // at $DIR/inline-options.rs:10:5: 10:21
let _3: (); // in scope 1 at $DIR/inline-options.rs:10:5: 10:21
let _4: (); // in scope 1 at $DIR/inline-options.rs:10:5: 10:21
let _5: (); // in scope 1 at $DIR/inline-options.rs:10:5: 10:21
}
bb0: {
StorageLive(_1); // scope 0 at $DIR/inline-options.rs:9:5: 9:18
_1 = not_inlined() -> bb1; // scope 0 at $DIR/inline-options.rs:9:5: 9:18
// mir::Constant
// + span: $DIR/inline-options.rs:9:5: 9:16
// + literal: Const { ty: fn() {not_inlined}, val: Value(Scalar(<ZST>)) }
}
bb1: {
StorageDead(_1); // scope 0 at $DIR/inline-options.rs:9:18: 9:19
StorageLive(_2); // scope 0 at $DIR/inline-options.rs:10:5: 10:21
StorageLive(_3); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
_3 = g() -> bb2; // scope 1 at $DIR/inline-options.rs:10:5: 10:21
// mir::Constant
// + span: $DIR/inline-options.rs:10:5: 10:21
// + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
}
bb2: {
StorageDead(_3); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
StorageLive(_4); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
_4 = g() -> bb3; // scope 1 at $DIR/inline-options.rs:10:5: 10:21
// mir::Constant
// + span: $DIR/inline-options.rs:10:5: 10:21
// + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
}
bb3: {
StorageDead(_4); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
StorageLive(_5); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
_5 = g() -> bb4; // scope 1 at $DIR/inline-options.rs:10:5: 10:21
// mir::Constant
// + span: $DIR/inline-options.rs:10:5: 10:21
// + literal: Const { ty: fn() {g}, val: Value(Scalar(<ZST>)) }
}
bb4: {
StorageDead(_5); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
_2 = const (); // scope 1 at $DIR/inline-options.rs:10:5: 10:21
StorageDead(_2); // scope 0 at $DIR/inline-options.rs:10:21: 10:22
_0 = const (); // scope 0 at $DIR/inline-options.rs:8:11: 11:2
return; // scope 0 at $DIR/inline-options.rs:11:2: 11:2
}
}