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tmiaskotmiasko
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Add flags customizing behaviour of MIR inlining
* `-Zinline-mir-threshold` to change the default threshold. * `-Zinline-mir-hint-threshold` to change the threshold used by functions with inline hint.
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5 files changed

+86
-4
lines changed

5 files changed

+86
-4
lines changed

‎compiler/rustc_interface/src/tests.rs

+2
Original file line numberDiff line numberDiff line change
@@ -554,6 +554,8 @@ fn test_debugging_options_tracking_hash() {
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tracked!(function_sections, Some(false));
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tracked!(human_readable_cgu_names, true);
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tracked!(inline_in_all_cgus, Some(true));
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tracked!(inline_mir_threshold, 123);
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tracked!(inline_mir_hint_threshold, 123);
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tracked!(insert_sideeffect, true);
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tracked!(instrument_coverage, true);
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tracked!(instrument_mcount, true);

‎compiler/rustc_mir/src/transform/inline.rs

+5-4
Original file line numberDiff line numberDiff line change
@@ -16,9 +16,6 @@ use crate::transform::MirPass;
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use std::iter;
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use std::ops::{Range, RangeFrom};
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const DEFAULT_THRESHOLD: usize = 50;
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const HINT_THRESHOLD: usize = 100;
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const INSTR_COST: usize = 5;
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const CALL_PENALTY: usize = 25;
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const LANDINGPAD_PENALTY: usize = 50;
@@ -248,7 +245,11 @@ impl Inliner<'tcx> {
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}
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}
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let mut threshold = if hinted { HINT_THRESHOLD } else { DEFAULT_THRESHOLD };
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let mut threshold = if hinted {
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self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold
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} else {
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self.tcx.sess.opts.debugging_opts.inline_mir_threshold
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};
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// Significantly lower the threshold for inlining cold functions
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if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::COLD) {

‎compiler/rustc_session/src/options.rs

+4
Original file line numberDiff line numberDiff line change
@@ -929,6 +929,10 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
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(default: no)"),
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incremental_verify_ich: bool = (false, parse_bool, [UNTRACKED],
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"verify incr. comp. hashes of green query instances (default: no)"),
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inline_mir_threshold: usize = (50, parse_uint, [TRACKED],
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"a default MIR inlining threshold (default: 50)"),
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inline_mir_hint_threshold: usize = (100, parse_uint, [TRACKED],
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"inlining threshold for functions with inline hint (default: 100)"),
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inline_in_all_cgus: Option<bool> = (None, parse_opt_bool, [TRACKED],
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"control whether `#[inline]` functions are in all CGUs"),
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input_stats: bool = (false, parse_bool, [UNTRACKED],

‎src/test/mir-opt/inline/inline-options.rs

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

‎src/test/mir-opt/inline/inline_options.main.Inline.after.mir

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

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