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Don't use scary block reorderings

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Oliver Schneider 2018-01-28 14:11:55 +01:00 committed by Oliver Schneider
parent 5b247b9bbe
commit edb2af58e4
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1 changed files with 4 additions and 56 deletions
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60
src/librustc_mir/transform/instcombine.rs
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@ -12,8 +12,8 @@
use rustc::mir::{Constant, Literal, Location, Place, Mir, Operand, ProjectionElem, Rvalue, Local};
use rustc::mir::{NullOp, StatementKind, Statement, BasicBlock, LocalKind};
use rustc::mir::{SourceInfo, ARGUMENT_VISIBILITY_SCOPE, TerminatorKind};
use rustc::mir::visit::{MutVisitor, Visitor, TyContext};
use rustc::mir::TerminatorKind;
use rustc::mir::visit::{MutVisitor, Visitor};
use rustc::middle::const_val::ConstVal;
use rustc::ty::{TyCtxt, TypeVariants, self, Instance};
use rustc::mir::interpret::{Value, PrimVal, GlobalId};
@ -21,10 +21,8 @@ use interpret::{eval_body_with_mir, eval_body, mk_borrowck_eval_cx, unary_op, Va
use rustc::util::nodemap::{FxHashMap, FxHashSet};
use rustc_data_structures::indexed_vec::Idx;
use std::mem;
use std::collections::VecDeque;
use transform::{MirPass, MirSource};
use syntax::codemap::Span;
use rustc_data_structures::control_flow_graph::ControlFlowGraph;
use rustc::ty::subst::Substs;
pub struct InstCombine;
@ -73,7 +71,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for InstCombineVisitor<'a, 'tcx> {
}
if let Some(constant) = self.optimizations.arrays_lengths.remove(&location) {
debug!("Replacing `Len([_; N])`: {:?}", rvalue);
debug!("Replacing `Len([_; N])`: {:?} with {:?}", rvalue, constant);
*rvalue = Rvalue::Use(Operand::Constant(box constant));
}
@ -101,6 +99,7 @@ impl<'a, 'tcx> MutVisitor<'tcx> for InstCombineVisitor<'a, 'tcx> {
) {
self.super_constant(constant, location);
if let Some(&(val, ty, _)) = self.optimizations.constants.get(constant) {
debug!("Replacing `{:?}` with {:?}:{:?}", constant.literal, val, ty);
constant.literal = Literal::Value {
value: self.tcx.mk_const(ty::Const {
val: ConstVal::Value(val),
@ -464,57 +463,6 @@ impl<'tcx> Visitor<'tcx> for ConstPropVisitor {
}
impl<'b, 'a, 'tcx> Visitor<'tcx> for OptimizationFinder<'b, 'a, 'tcx> {
// override to visit basic blocks in execution order
fn super_mir(&mut self, mir: &Mir<'tcx>) {
let mut seen = FxHashSet::default();
seen.insert(mir.start_node());
let mut sorted = Vec::new();
let mut next = VecDeque::new();
sorted.push(mir.start_node());
next.push_back(mir.start_node());
while let Some(current) = next.pop_front() {
for successor in mir.successors(current) {
trace!("checking successor of {:?}: {:?}", current, successor);
trace!("{:?}, {:?}", sorted, next);
if seen.contains(&successor) {
for &pending in &next {
// not a back-edge, just a branch merging back into a single execution
if pending == successor {
// move to the back of the queue
let i = sorted.iter().position(|&b| b == successor).unwrap();
sorted.remove(i);
sorted.push(successor);
break;
}
}
} else {
seen.insert(successor);
sorted.push(successor);
next.push_back(successor);
}
}
}
trace!("checking basic blocks: {:?}", sorted);
for bb in sorted {
self.visit_basic_block_data(bb, &mir[bb]);
}
for scope in &mir.visibility_scopes {
self.visit_visibility_scope_data(scope);
}
self.visit_ty(&mir.return_ty(), TyContext::ReturnTy(SourceInfo {
span: mir.span,
scope: ARGUMENT_VISIBILITY_SCOPE,
}));
for local in mir.local_decls.indices() {
self.visit_local_decl(local, &mir.local_decls[local]);
}
self.visit_span(&mir.span);
}
fn visit_constant(
&mut self,
constant: &Constant<'tcx>,