Auto merge of #76683 - simonvandel:inst-combine-deref, r=oli-obk
Add optimization to avoid load of address Look for the sequence ```rust _2 = &_1; ... _5 = (*_2) ``` in which we can replace the last statement with `_5 = _1` to avoid the load of _2
This commit is contained in:
bors
commit
f47df31ae5
10 changed files with 506 additions and 12 deletions
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@ -4,9 +4,14 @@ use crate::transform::{MirPass, MirSource};
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_hir::Mutability;
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use rustc_index::vec::Idx;
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use rustc_middle::mir::visit::{MutVisitor, Visitor};
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use rustc_middle::mir::{
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BinOp, Body, Constant, Local, Location, Operand, Place, PlaceRef, ProjectionElem, Rvalue,
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visit::PlaceContext,
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visit::{MutVisitor, Visitor},
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Statement,
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};
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use rustc_middle::mir::{
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BinOp, Body, BorrowKind, Constant, Local, Location, Operand, Place, PlaceRef, ProjectionElem,
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Rvalue,
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};
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use rustc_middle::ty::{self, TyCtxt};
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use std::mem;
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@ -71,10 +76,36 @@ impl<'tcx> MutVisitor<'tcx> for InstCombineVisitor<'tcx> {
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*rvalue = Rvalue::Use(operand);
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}
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if let Some(place) = self.optimizations.unneeded_deref.remove(&location) {
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debug!("unneeded_deref: replacing {:?} with {:?}", rvalue, place);
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*rvalue = Rvalue::Use(Operand::Copy(place));
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}
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self.super_rvalue(rvalue, location)
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}
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}
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struct MutatingUseVisitor {
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has_mutating_use: bool,
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local_to_look_for: Local,
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}
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impl MutatingUseVisitor {
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fn has_mutating_use_in_stmt(local: Local, stmt: &Statement<'tcx>, location: Location) -> bool {
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let mut _self = Self { has_mutating_use: false, local_to_look_for: local };
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_self.visit_statement(stmt, location);
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_self.has_mutating_use
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}
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}
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impl<'tcx> Visitor<'tcx> for MutatingUseVisitor {
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fn visit_local(&mut self, local: &Local, context: PlaceContext, _: Location) {
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if *local == self.local_to_look_for {
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self.has_mutating_use |= context.is_mutating_use();
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}
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}
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}
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/// Finds optimization opportunities on the MIR.
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struct OptimizationFinder<'b, 'tcx> {
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body: &'b Body<'tcx>,
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@ -87,6 +118,85 @@ impl OptimizationFinder<'b, 'tcx> {
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OptimizationFinder { body, tcx, optimizations: OptimizationList::default() }
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}
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fn find_deref_of_address(&mut self, rvalue: &Rvalue<'tcx>, location: Location) -> Option<()> {
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// Look for the sequence
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//
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// _2 = &_1;
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// ...
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// _5 = (*_2);
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//
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// which we can replace the last statement with `_5 = _1;` to avoid the load of `_2`.
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if let Rvalue::Use(op) = rvalue {
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let local_being_derefed = match op.place()?.as_ref() {
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PlaceRef { local, projection: [ProjectionElem::Deref] } => Some(local),
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_ => None,
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}?;
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let stmt_index = location.statement_index;
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// Look behind for statement that assigns the local from a address of operator.
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// 6 is chosen as a heuristic determined by seeing the number of times
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// the optimization kicked in compiling rust std.
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let lower_index = stmt_index.saturating_sub(6);
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let statements_to_look_in = self.body.basic_blocks()[location.block].statements
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[lower_index..stmt_index]
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.iter()
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.rev();
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for stmt in statements_to_look_in {
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match &stmt.kind {
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// Exhaustive match on statements to detect conditions that warrant we bail out of the optimization.
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rustc_middle::mir::StatementKind::Assign(box (l, r))
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if l.local == local_being_derefed =>
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{
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match r {
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// Looking for immutable reference e.g _local_being_deref = &_1;
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Rvalue::Ref(
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_,
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// Only apply the optimization if it is an immutable borrow.
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BorrowKind::Shared,
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place_taken_address_of,
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) => {
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self.optimizations
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.unneeded_deref
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.insert(location, *place_taken_address_of);
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return Some(());
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}
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// We found an assignment of `local_being_deref` that is not an immutable ref, e.g the following sequence
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// _2 = &_1;
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// _3 = &5
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// _2 = _3; <-- this means it is no longer valid to replace the last statement with `_5 = _1;`
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// _5 = (*_2);
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_ => return None,
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}
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}
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// Inline asm can do anything, so bail out of the optimization.
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rustc_middle::mir::StatementKind::LlvmInlineAsm(_) => return None,
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// Check that `local_being_deref` is not being used in a mutating way which can cause misoptimization.
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rustc_middle::mir::StatementKind::Assign(box (_, _))
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| rustc_middle::mir::StatementKind::Coverage(_)
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| rustc_middle::mir::StatementKind::Nop
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| rustc_middle::mir::StatementKind::FakeRead(_, _)
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| rustc_middle::mir::StatementKind::StorageLive(_)
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| rustc_middle::mir::StatementKind::StorageDead(_)
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| rustc_middle::mir::StatementKind::Retag(_, _)
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| rustc_middle::mir::StatementKind::AscribeUserType(_, _)
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| rustc_middle::mir::StatementKind::SetDiscriminant { .. } => {
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if MutatingUseVisitor::has_mutating_use_in_stmt(
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local_being_derefed,
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stmt,
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location,
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) {
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return None;
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}
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}
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}
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}
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}
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Some(())
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}
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fn find_unneeded_equality_comparison(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
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// find Ne(_place, false) or Ne(false, _place)
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// or Eq(_place, true) or Eq(true, _place)
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@ -153,6 +263,8 @@ impl Visitor<'tcx> for OptimizationFinder<'b, 'tcx> {
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}
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}
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let _ = self.find_deref_of_address(rvalue, location);
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self.find_unneeded_equality_comparison(rvalue, location);
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self.super_rvalue(rvalue, location)
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@ -164,4 +276,5 @@ struct OptimizationList<'tcx> {
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and_stars: FxHashSet<Location>,
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arrays_lengths: FxHashMap<Location, Constant<'tcx>>,
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unneeded_equality_comparison: FxHashMap<Location, Operand<'tcx>>,
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unneeded_deref: FxHashMap<Location, Place<'tcx>>,
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}
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@ -19,7 +19,7 @@
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// + span: $DIR/ref_deref.rs:5:6: 5:10
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// + literal: Const { ty: &i32, val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref[317d]::main[0]), const_param_did: None }, [], Some(promoted[0])) }
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_2 = _4; // scope 0 at $DIR/ref_deref.rs:5:6: 5:10
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- _1 = (*_2); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10
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- _1 = (*_4); // scope 0 at $DIR/ref_deref.rs:5:5: 5:10
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+ _1 = const 4_i32; // scope 0 at $DIR/ref_deref.rs:5:5: 5:10
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StorageDead(_2); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11
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StorageDead(_1); // scope 0 at $DIR/ref_deref.rs:5:10: 5:11
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@ -19,7 +19,7 @@
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// + span: $DIR/ref_deref_project.rs:5:6: 5:17
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// + literal: Const { ty: &(i32, i32), val: Unevaluated(WithOptConstParam { did: DefId(0:3 ~ ref_deref_project[317d]::main[0]), const_param_did: None }, [], Some(promoted[0])) }
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_2 = &((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:6: 5:17
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_1 = (*_2); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17
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_1 = ((*_4).1: i32); // scope 0 at $DIR/ref_deref_project.rs:5:5: 5:17
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StorageDead(_2); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18
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StorageDead(_1); // scope 0 at $DIR/ref_deref_project.rs:5:17: 5:18
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_0 = const (); // scope 0 at $DIR/ref_deref_project.rs:4:11: 6:2
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@ -9,13 +9,14 @@ fn foo(_1: T, _2: &i32) -> i32 {
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let mut _5: (&i32, &i32); // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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let mut _6: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:7: 16:8
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let mut _7: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:10: 16:11
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let mut _8: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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let mut _9: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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let mut _10: &i32; // in scope 0 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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scope 1 {
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debug x => _3; // in scope 1 at $DIR/inline-closure-borrows-arg.rs:12:9: 12:10
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scope 2 {
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debug r => _8; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:14: 12:15
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debug _s => _9; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:23: 12:25
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debug r => _9; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:14: 12:15
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debug _s => _10; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:12:23: 12:25
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let _8: &i32; // in scope 2 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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}
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}
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scope 3 {
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@ -33,13 +34,16 @@ fn foo(_1: T, _2: &i32) -> i32 {
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_7 = &(*_2); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:10: 16:11
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(_5.0: &i32) = move _6; // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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(_5.1: &i32) = move _7; // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageLive(_8); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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_8 = move (_5.0: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageLive(_9); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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_9 = move (_5.1: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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_0 = (*_8); // scope 3 at $DIR/inline-closure-borrows-arg.rs:14:9: 14:18
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_9 = move (_5.0: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageLive(_10); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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_10 = move (_5.1: &i32); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageLive(_8); // scope 2 at $DIR/inline-closure-borrows-arg.rs:13:13: 13:21
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_8 = _9; // scope 2 at $DIR/inline-closure-borrows-arg.rs:13:24: 13:27
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_0 = (*_9); // scope 3 at $DIR/inline-closure-borrows-arg.rs:14:9: 14:18
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StorageDead(_8); // scope 2 at $DIR/inline-closure-borrows-arg.rs:15:5: 15:6
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StorageDead(_10); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageDead(_9); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageDead(_8); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:5: 16:12
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StorageDead(_7); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12
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StorageDead(_6); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12
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StorageDead(_5); // scope 1 at $DIR/inline-closure-borrows-arg.rs:16:11: 16:12
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@ -0,0 +1,92 @@
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- // MIR for `deep_opt` before InstCombine
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+ // MIR for `deep_opt` after InstCombine
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fn deep_opt() -> (u64, u64, u64) {
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let mut _0: (u64, u64, u64); // return place in scope 0 at $DIR/inst_combine_deref.rs:11:18: 11:33
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let _1: u64; // in scope 0 at $DIR/inst_combine_deref.rs:12:9: 12:11
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let mut _10: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:6: 21:8
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let mut _11: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:10: 21:12
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let mut _12: u64; // in scope 0 at $DIR/inst_combine_deref.rs:21:14: 21:16
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scope 1 {
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debug x1 => _1; // in scope 1 at $DIR/inst_combine_deref.rs:12:9: 12:11
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let _2: u64; // in scope 1 at $DIR/inst_combine_deref.rs:13:9: 13:11
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scope 2 {
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debug x2 => _2; // in scope 2 at $DIR/inst_combine_deref.rs:13:9: 13:11
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let _3: u64; // in scope 2 at $DIR/inst_combine_deref.rs:14:9: 14:11
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scope 3 {
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debug x3 => _3; // in scope 3 at $DIR/inst_combine_deref.rs:14:9: 14:11
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let _4: &u64; // in scope 3 at $DIR/inst_combine_deref.rs:15:9: 15:11
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scope 4 {
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debug y1 => _4; // in scope 4 at $DIR/inst_combine_deref.rs:15:9: 15:11
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let _5: &u64; // in scope 4 at $DIR/inst_combine_deref.rs:16:9: 16:11
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scope 5 {
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debug y2 => _5; // in scope 5 at $DIR/inst_combine_deref.rs:16:9: 16:11
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let _6: &u64; // in scope 5 at $DIR/inst_combine_deref.rs:17:9: 17:11
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scope 6 {
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debug y3 => _6; // in scope 6 at $DIR/inst_combine_deref.rs:17:9: 17:11
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let _7: u64; // in scope 6 at $DIR/inst_combine_deref.rs:18:9: 18:11
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scope 7 {
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debug z1 => _7; // in scope 7 at $DIR/inst_combine_deref.rs:18:9: 18:11
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let _8: u64; // in scope 7 at $DIR/inst_combine_deref.rs:19:9: 19:11
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scope 8 {
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debug z2 => _8; // in scope 8 at $DIR/inst_combine_deref.rs:19:9: 19:11
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let _9: u64; // in scope 8 at $DIR/inst_combine_deref.rs:20:9: 20:11
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scope 9 {
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debug z3 => _9; // in scope 9 at $DIR/inst_combine_deref.rs:20:9: 20:11
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}
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}
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}
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}
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}
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}
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}
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}
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}
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bb0: {
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StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:12:9: 12:11
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_1 = const 1_u64; // scope 0 at $DIR/inst_combine_deref.rs:12:14: 12:15
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StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:13:9: 13:11
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_2 = const 2_u64; // scope 1 at $DIR/inst_combine_deref.rs:13:14: 13:15
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StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:14:9: 14:11
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_3 = const 3_u64; // scope 2 at $DIR/inst_combine_deref.rs:14:14: 14:15
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StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:15:9: 15:11
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_4 = &_1; // scope 3 at $DIR/inst_combine_deref.rs:15:14: 15:17
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StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:16:9: 16:11
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_5 = &_2; // scope 4 at $DIR/inst_combine_deref.rs:16:14: 16:17
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StorageLive(_6); // scope 5 at $DIR/inst_combine_deref.rs:17:9: 17:11
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_6 = &_3; // scope 5 at $DIR/inst_combine_deref.rs:17:14: 17:17
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StorageLive(_7); // scope 6 at $DIR/inst_combine_deref.rs:18:9: 18:11
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- _7 = (*_4); // scope 6 at $DIR/inst_combine_deref.rs:18:14: 18:17
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+ _7 = _1; // scope 6 at $DIR/inst_combine_deref.rs:18:14: 18:17
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StorageLive(_8); // scope 7 at $DIR/inst_combine_deref.rs:19:9: 19:11
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- _8 = (*_5); // scope 7 at $DIR/inst_combine_deref.rs:19:14: 19:17
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+ _8 = _2; // scope 7 at $DIR/inst_combine_deref.rs:19:14: 19:17
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StorageLive(_9); // scope 8 at $DIR/inst_combine_deref.rs:20:9: 20:11
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- _9 = (*_6); // scope 8 at $DIR/inst_combine_deref.rs:20:14: 20:17
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+ _9 = _3; // scope 8 at $DIR/inst_combine_deref.rs:20:14: 20:17
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StorageLive(_10); // scope 9 at $DIR/inst_combine_deref.rs:21:6: 21:8
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_10 = _7; // scope 9 at $DIR/inst_combine_deref.rs:21:6: 21:8
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StorageLive(_11); // scope 9 at $DIR/inst_combine_deref.rs:21:10: 21:12
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_11 = _8; // scope 9 at $DIR/inst_combine_deref.rs:21:10: 21:12
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StorageLive(_12); // scope 9 at $DIR/inst_combine_deref.rs:21:14: 21:16
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_12 = _9; // scope 9 at $DIR/inst_combine_deref.rs:21:14: 21:16
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(_0.0: u64) = move _10; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17
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(_0.1: u64) = move _11; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17
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(_0.2: u64) = move _12; // scope 9 at $DIR/inst_combine_deref.rs:21:5: 21:17
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StorageDead(_12); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17
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StorageDead(_11); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17
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StorageDead(_10); // scope 9 at $DIR/inst_combine_deref.rs:21:16: 21:17
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StorageDead(_9); // scope 8 at $DIR/inst_combine_deref.rs:22:1: 22:2
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StorageDead(_8); // scope 7 at $DIR/inst_combine_deref.rs:22:1: 22:2
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StorageDead(_7); // scope 6 at $DIR/inst_combine_deref.rs:22:1: 22:2
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StorageDead(_6); // scope 5 at $DIR/inst_combine_deref.rs:22:1: 22:2
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StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:22:1: 22:2
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StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:22:1: 22:2
|
||||
StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:22:1: 22:2
|
||||
StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:22:1: 22:2
|
||||
StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:22:1: 22:2
|
||||
return; // scope 0 at $DIR/inst_combine_deref.rs:22:2: 22:2
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -0,0 +1,85 @@
|
|||
- // MIR for `do_not_miscompile` before InstCombine
|
||||
+ // MIR for `do_not_miscompile` after InstCombine
|
||||
|
||||
fn do_not_miscompile() -> () {
|
||||
let mut _0: (); // return place in scope 0 at $DIR/inst_combine_deref.rs:54:24: 54:24
|
||||
let _1: i32; // in scope 0 at $DIR/inst_combine_deref.rs:55:9: 55:10
|
||||
let mut _5: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
let _6: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
let _7: (); // in scope 0 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
let mut _8: bool; // in scope 0 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
let mut _9: bool; // in scope 0 at $DIR/inst_combine_deref.rs:60:13: 60:21
|
||||
let mut _10: i32; // in scope 0 at $DIR/inst_combine_deref.rs:60:13: 60:15
|
||||
let mut _11: !; // in scope 0 at $SRC_DIR/std/src/macros.rs:LL:COL
|
||||
scope 1 {
|
||||
debug x => _1; // in scope 1 at $DIR/inst_combine_deref.rs:55:9: 55:10
|
||||
let _2: i32; // in scope 1 at $DIR/inst_combine_deref.rs:56:9: 56:10
|
||||
scope 2 {
|
||||
debug a => _2; // in scope 2 at $DIR/inst_combine_deref.rs:56:9: 56:10
|
||||
let mut _3: &i32; // in scope 2 at $DIR/inst_combine_deref.rs:57:9: 57:14
|
||||
scope 3 {
|
||||
debug y => _3; // in scope 3 at $DIR/inst_combine_deref.rs:57:9: 57:14
|
||||
let _4: &mut &i32; // in scope 3 at $DIR/inst_combine_deref.rs:58:9: 58:10
|
||||
scope 4 {
|
||||
debug z => _4; // in scope 4 at $DIR/inst_combine_deref.rs:58:9: 58:10
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bb0: {
|
||||
StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:55:9: 55:10
|
||||
_1 = const 42_i32; // scope 0 at $DIR/inst_combine_deref.rs:55:13: 55:15
|
||||
StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:56:9: 56:10
|
||||
_2 = const 99_i32; // scope 1 at $DIR/inst_combine_deref.rs:56:13: 56:15
|
||||
StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:57:9: 57:14
|
||||
_3 = &_1; // scope 2 at $DIR/inst_combine_deref.rs:57:17: 57:19
|
||||
StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:58:9: 58:10
|
||||
_4 = &mut _3; // scope 3 at $DIR/inst_combine_deref.rs:58:13: 58:19
|
||||
StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
StorageLive(_6); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
_6 = &_2; // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
- _5 = &(*_6); // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
+ _5 = _6; // scope 4 at $DIR/inst_combine_deref.rs:59:10: 59:12
|
||||
(*_4) = move _5; // scope 4 at $DIR/inst_combine_deref.rs:59:5: 59:12
|
||||
StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:59:11: 59:12
|
||||
StorageDead(_6); // scope 4 at $DIR/inst_combine_deref.rs:59:12: 59:13
|
||||
StorageLive(_7); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
StorageLive(_8); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
StorageLive(_9); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:21
|
||||
StorageLive(_10); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:15
|
||||
_10 = (*_3); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:15
|
||||
_9 = Eq(move _10, const 99_i32); // scope 4 at $DIR/inst_combine_deref.rs:60:13: 60:21
|
||||
StorageDead(_10); // scope 4 at $DIR/inst_combine_deref.rs:60:20: 60:21
|
||||
_8 = Not(move _9); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
StorageDead(_9); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23
|
||||
switchInt(_8) -> [false: bb1, otherwise: bb2]; // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
}
|
||||
|
||||
bb1: {
|
||||
_7 = const (); // scope 4 at $DIR/inst_combine_deref.rs:60:5: 60:23
|
||||
StorageDead(_8); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23
|
||||
StorageDead(_7); // scope 4 at $DIR/inst_combine_deref.rs:60:22: 60:23
|
||||
_0 = const (); // scope 0 at $DIR/inst_combine_deref.rs:54:24: 61:2
|
||||
StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:61:1: 61:2
|
||||
StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:61:1: 61:2
|
||||
StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:61:1: 61:2
|
||||
StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:61:1: 61:2
|
||||
return; // scope 0 at $DIR/inst_combine_deref.rs:61:2: 61:2
|
||||
}
|
||||
|
||||
bb2: {
|
||||
StorageLive(_11); // scope 4 at $SRC_DIR/std/src/macros.rs:LL:COL
|
||||
begin_panic::<&str>(const "assertion failed: *y == 99"); // scope 4 at $SRC_DIR/std/src/macros.rs:LL:COL
|
||||
// mir::Constant
|
||||
// + span: $SRC_DIR/std/src/macros.rs:LL:COL
|
||||
// + literal: Const { ty: fn(&str) -> ! {std::rt::begin_panic::<&str>}, val: Value(Scalar(<ZST>)) }
|
||||
// ty::Const
|
||||
// + ty: &str
|
||||
// + val: Value(Slice { data: Allocation { bytes: [97, 115, 115, 101, 114, 116, 105, 111, 110, 32, 102, 97, 105, 108, 101, 100, 58, 32, 42, 121, 32, 61, 61, 32, 57, 57], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [67108863], len: Size { raw: 26 } }, size: Size { raw: 26 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 26 })
|
||||
// mir::Constant
|
||||
// + span: $DIR/inst_combine_deref.rs:1:1: 1:1
|
||||
// + literal: Const { ty: &str, val: Value(Slice { data: Allocation { bytes: [97, 115, 115, 101, 114, 116, 105, 111, 110, 32, 102, 97, 105, 108, 101, 100, 58, 32, 42, 121, 32, 61, 61, 32, 57, 57], relocations: Relocations(SortedMap { data: [] }), init_mask: InitMask { blocks: [67108863], len: Size { raw: 26 } }, size: Size { raw: 26 }, align: Align { pow2: 0 }, mutability: Not, extra: () }, start: 0, end: 26 }) }
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -0,0 +1,53 @@
|
|||
- // MIR for `dont_opt` before InstCombine
|
||||
+ // MIR for `dont_opt` after InstCombine
|
||||
|
||||
fn dont_opt() -> u64 {
|
||||
let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:43:18: 43:21
|
||||
let _1: i32; // in scope 0 at $DIR/inst_combine_deref.rs:44:9: 44:10
|
||||
let mut _5: &i32; // in scope 0 at $DIR/inst_combine_deref.rs:48:10: 48:14
|
||||
scope 1 {
|
||||
debug y => _1; // in scope 1 at $DIR/inst_combine_deref.rs:44:9: 44:10
|
||||
let _2: &i32; // in scope 1 at $DIR/inst_combine_deref.rs:45:9: 45:13
|
||||
scope 2 {
|
||||
debug _ref => _2; // in scope 2 at $DIR/inst_combine_deref.rs:45:9: 45:13
|
||||
let _3: i32; // in scope 2 at $DIR/inst_combine_deref.rs:46:9: 46:10
|
||||
scope 3 {
|
||||
debug x => _3; // in scope 3 at $DIR/inst_combine_deref.rs:46:9: 46:10
|
||||
let mut _4: &i32; // in scope 3 at $DIR/inst_combine_deref.rs:47:9: 47:15
|
||||
scope 4 {
|
||||
debug _1 => _4; // in scope 4 at $DIR/inst_combine_deref.rs:47:9: 47:15
|
||||
let _6: i32; // in scope 4 at $DIR/inst_combine_deref.rs:49:9: 49:11
|
||||
scope 5 {
|
||||
debug _4 => _6; // in scope 5 at $DIR/inst_combine_deref.rs:49:9: 49:11
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bb0: {
|
||||
StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:44:9: 44:10
|
||||
_1 = const 5_i32; // scope 0 at $DIR/inst_combine_deref.rs:44:13: 44:14
|
||||
StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:45:9: 45:13
|
||||
_2 = &_1; // scope 1 at $DIR/inst_combine_deref.rs:45:16: 45:18
|
||||
StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:46:9: 46:10
|
||||
_3 = const 5_i32; // scope 2 at $DIR/inst_combine_deref.rs:46:13: 46:14
|
||||
StorageLive(_4); // scope 3 at $DIR/inst_combine_deref.rs:47:9: 47:15
|
||||
_4 = &_3; // scope 3 at $DIR/inst_combine_deref.rs:47:18: 47:20
|
||||
StorageLive(_5); // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14
|
||||
- _5 = &(*_2); // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14
|
||||
+ _5 = _2; // scope 4 at $DIR/inst_combine_deref.rs:48:10: 48:14
|
||||
_4 = move _5; // scope 4 at $DIR/inst_combine_deref.rs:48:5: 48:14
|
||||
StorageDead(_5); // scope 4 at $DIR/inst_combine_deref.rs:48:13: 48:14
|
||||
StorageLive(_6); // scope 4 at $DIR/inst_combine_deref.rs:49:9: 49:11
|
||||
_6 = (*_4); // scope 4 at $DIR/inst_combine_deref.rs:49:14: 49:17
|
||||
_0 = const 0_u64; // scope 5 at $DIR/inst_combine_deref.rs:50:5: 50:6
|
||||
StorageDead(_6); // scope 4 at $DIR/inst_combine_deref.rs:51:1: 51:2
|
||||
StorageDead(_4); // scope 3 at $DIR/inst_combine_deref.rs:51:1: 51:2
|
||||
StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:51:1: 51:2
|
||||
StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:51:1: 51:2
|
||||
StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:51:1: 51:2
|
||||
return; // scope 0 at $DIR/inst_combine_deref.rs:51:2: 51:2
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -0,0 +1,44 @@
|
|||
- // MIR for `opt_struct` before InstCombine
|
||||
+ // MIR for `opt_struct` after InstCombine
|
||||
|
||||
fn opt_struct(_1: S) -> u64 {
|
||||
debug s => _1; // in scope 0 at $DIR/inst_combine_deref.rs:30:15: 30:16
|
||||
let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:30:24: 30:27
|
||||
let _2: &u64; // in scope 0 at $DIR/inst_combine_deref.rs:31:9: 31:10
|
||||
let mut _5: u64; // in scope 0 at $DIR/inst_combine_deref.rs:34:5: 34:7
|
||||
let mut _6: u64; // in scope 0 at $DIR/inst_combine_deref.rs:34:10: 34:11
|
||||
scope 1 {
|
||||
debug a => _2; // in scope 1 at $DIR/inst_combine_deref.rs:31:9: 31:10
|
||||
let _3: &u64; // in scope 1 at $DIR/inst_combine_deref.rs:32:9: 32:10
|
||||
scope 2 {
|
||||
debug b => _3; // in scope 2 at $DIR/inst_combine_deref.rs:32:9: 32:10
|
||||
let _4: u64; // in scope 2 at $DIR/inst_combine_deref.rs:33:9: 33:10
|
||||
scope 3 {
|
||||
debug x => _4; // in scope 3 at $DIR/inst_combine_deref.rs:33:9: 33:10
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bb0: {
|
||||
StorageLive(_2); // scope 0 at $DIR/inst_combine_deref.rs:31:9: 31:10
|
||||
_2 = &(_1.0: u64); // scope 0 at $DIR/inst_combine_deref.rs:31:13: 31:17
|
||||
StorageLive(_3); // scope 1 at $DIR/inst_combine_deref.rs:32:9: 32:10
|
||||
_3 = &(_1.1: u64); // scope 1 at $DIR/inst_combine_deref.rs:32:13: 32:17
|
||||
StorageLive(_4); // scope 2 at $DIR/inst_combine_deref.rs:33:9: 33:10
|
||||
- _4 = (*_2); // scope 2 at $DIR/inst_combine_deref.rs:33:13: 33:15
|
||||
+ _4 = (_1.0: u64); // scope 2 at $DIR/inst_combine_deref.rs:33:13: 33:15
|
||||
StorageLive(_5); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7
|
||||
- _5 = (*_3); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7
|
||||
+ _5 = (_1.1: u64); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:7
|
||||
StorageLive(_6); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11
|
||||
_6 = _4; // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11
|
||||
_0 = Add(move _5, move _6); // scope 3 at $DIR/inst_combine_deref.rs:34:5: 34:11
|
||||
StorageDead(_6); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11
|
||||
StorageDead(_5); // scope 3 at $DIR/inst_combine_deref.rs:34:10: 34:11
|
||||
StorageDead(_4); // scope 2 at $DIR/inst_combine_deref.rs:35:1: 35:2
|
||||
StorageDead(_3); // scope 1 at $DIR/inst_combine_deref.rs:35:1: 35:2
|
||||
StorageDead(_2); // scope 0 at $DIR/inst_combine_deref.rs:35:1: 35:2
|
||||
return; // scope 0 at $DIR/inst_combine_deref.rs:35:2: 35:2
|
||||
}
|
||||
}
|
||||
|
||||
69
src/test/mir-opt/inst_combine_deref.rs
Normal file
69
src/test/mir-opt/inst_combine_deref.rs
Normal file
|
|
@ -0,0 +1,69 @@
|
|||
// compile-flags: -O
|
||||
// EMIT_MIR inst_combine_deref.simple_opt.InstCombine.diff
|
||||
fn simple_opt() -> u64 {
|
||||
let x = 5;
|
||||
let y = &x;
|
||||
let z = *y;
|
||||
z
|
||||
}
|
||||
|
||||
// EMIT_MIR inst_combine_deref.deep_opt.InstCombine.diff
|
||||
fn deep_opt() -> (u64, u64, u64) {
|
||||
let x1 = 1;
|
||||
let x2 = 2;
|
||||
let x3 = 3;
|
||||
let y1 = &x1;
|
||||
let y2 = &x2;
|
||||
let y3 = &x3;
|
||||
let z1 = *y1;
|
||||
let z2 = *y2;
|
||||
let z3 = *y3;
|
||||
(z1, z2, z3)
|
||||
}
|
||||
|
||||
struct S {
|
||||
a: u64,
|
||||
b: u64,
|
||||
}
|
||||
|
||||
// EMIT_MIR inst_combine_deref.opt_struct.InstCombine.diff
|
||||
fn opt_struct(s: S) -> u64 {
|
||||
let a = &s.a;
|
||||
let b = &s.b;
|
||||
let x = *a;
|
||||
*b + x
|
||||
}
|
||||
|
||||
// EMIT_MIR inst_combine_deref.dont_opt.InstCombine.diff
|
||||
// do not optimize a sequence looking like this:
|
||||
// _1 = &_2;
|
||||
// _1 = _3;
|
||||
// _4 = *_1;
|
||||
// as the _1 = _3 assignment makes it not legal to replace the last statement with _4 = _2
|
||||
fn dont_opt() -> u64 {
|
||||
let y = 5;
|
||||
let _ref = &y;
|
||||
let x = 5;
|
||||
let mut _1 = &x;
|
||||
_1 = _ref;
|
||||
let _4 = *_1;
|
||||
0
|
||||
}
|
||||
|
||||
// EMIT_MIR inst_combine_deref.do_not_miscompile.InstCombine.diff
|
||||
fn do_not_miscompile() {
|
||||
let x = 42;
|
||||
let a = 99;
|
||||
let mut y = &x;
|
||||
let z = &mut y;
|
||||
*z = &a;
|
||||
assert!(*y == 99);
|
||||
}
|
||||
|
||||
fn main() {
|
||||
simple_opt();
|
||||
deep_opt();
|
||||
opt_struct(S { a: 0, b: 1 });
|
||||
dont_opt();
|
||||
do_not_miscompile();
|
||||
}
|
||||
|
|
@ -0,0 +1,34 @@
|
|||
- // MIR for `simple_opt` before InstCombine
|
||||
+ // MIR for `simple_opt` after InstCombine
|
||||
|
||||
fn simple_opt() -> u64 {
|
||||
let mut _0: u64; // return place in scope 0 at $DIR/inst_combine_deref.rs:3:20: 3:23
|
||||
let _1: u64; // in scope 0 at $DIR/inst_combine_deref.rs:4:9: 4:10
|
||||
scope 1 {
|
||||
debug x => _1; // in scope 1 at $DIR/inst_combine_deref.rs:4:9: 4:10
|
||||
let _2: &u64; // in scope 1 at $DIR/inst_combine_deref.rs:5:9: 5:10
|
||||
scope 2 {
|
||||
debug y => _2; // in scope 2 at $DIR/inst_combine_deref.rs:5:9: 5:10
|
||||
let _3: u64; // in scope 2 at $DIR/inst_combine_deref.rs:6:9: 6:10
|
||||
scope 3 {
|
||||
debug z => _3; // in scope 3 at $DIR/inst_combine_deref.rs:6:9: 6:10
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
bb0: {
|
||||
StorageLive(_1); // scope 0 at $DIR/inst_combine_deref.rs:4:9: 4:10
|
||||
_1 = const 5_u64; // scope 0 at $DIR/inst_combine_deref.rs:4:13: 4:14
|
||||
StorageLive(_2); // scope 1 at $DIR/inst_combine_deref.rs:5:9: 5:10
|
||||
_2 = &_1; // scope 1 at $DIR/inst_combine_deref.rs:5:13: 5:15
|
||||
StorageLive(_3); // scope 2 at $DIR/inst_combine_deref.rs:6:9: 6:10
|
||||
- _3 = (*_2); // scope 2 at $DIR/inst_combine_deref.rs:6:13: 6:15
|
||||
+ _3 = _1; // scope 2 at $DIR/inst_combine_deref.rs:6:13: 6:15
|
||||
_0 = _3; // scope 3 at $DIR/inst_combine_deref.rs:7:5: 7:6
|
||||
StorageDead(_3); // scope 2 at $DIR/inst_combine_deref.rs:8:1: 8:2
|
||||
StorageDead(_2); // scope 1 at $DIR/inst_combine_deref.rs:8:1: 8:2
|
||||
StorageDead(_1); // scope 0 at $DIR/inst_combine_deref.rs:8:1: 8:2
|
||||
return; // scope 0 at $DIR/inst_combine_deref.rs:8:2: 8:2
|
||||
}
|
||||
}
|
||||
|
||||
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Reference in a new issue