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[mir-opt] Turn on the ConstProp pass by default #66074

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Nov 19, 2019
Merged

[mir-opt] Turn on the ConstProp pass by default #66074

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41 changes: 27 additions & 14 deletions src/librustc_mir/transform/const_prop.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -641,8 +641,21 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
}
}

fn should_const_prop(&self) -> bool {
self.tcx.sess.opts.debugging_opts.mir_opt_level >= 2
fn should_const_prop(&mut self, op: OpTy<'tcx>) -> bool {
if self.tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
return true;
} else if self.tcx.sess.opts.debugging_opts.mir_opt_level == 0 {
return false;
}

match *op {
interpret::Operand::Immediate(Immediate::Scalar(ScalarMaybeUndef::Scalar(s))) =>
s.is_bits(),
interpret::Operand::Immediate(Immediate::ScalarPair(ScalarMaybeUndef::Scalar(l),
ScalarMaybeUndef::Scalar(r))) =>
l.is_bits() && r.is_bits(),
_ => false
}
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}
}

Expand Down Expand Up @@ -742,15 +755,15 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
if self.can_const_prop[local] {
trace!("propagated into {:?}", local);

if self.should_const_prop() {
let value =
self.get_const(local).expect("local was dead/uninitialized");
trace!("replacing {:?} with {:?}", rval, value);
self.replace_with_const(
rval,
value,
statement.source_info,
);
if let Some(value) = self.get_const(local) {
if self.should_const_prop(value) {
trace!("replacing {:?} with {:?}", rval, value);
self.replace_with_const(
rval,
value,
statement.source_info,
);
}
}
} else {
trace!("can't propagate into {:?}", local);
Expand Down Expand Up @@ -852,7 +865,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
&msg,
);
} else {
if self.should_const_prop() {
if self.should_const_prop(value) {
if let ScalarMaybeUndef::Scalar(scalar) = value_const {
*cond = self.operand_from_scalar(
scalar,
Expand All @@ -865,8 +878,8 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
}
},
TerminatorKind::SwitchInt { ref mut discr, switch_ty, .. } => {
if self.should_const_prop() {
if let Some(value) = self.eval_operand(&discr, source_info) {
if let Some(value) = self.eval_operand(&discr, source_info) {
if self.should_const_prop(value) {
if let ScalarMaybeUndef::Scalar(scalar) =
self.ecx.read_scalar(value).unwrap() {
*discr = self.operand_from_scalar(scalar, switch_ty, source_info.span);
Expand Down
6 changes: 3 additions & 3 deletions src/test/codegen/optimize-attr-1.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@

// CHECK-LABEL: define i32 @nothing
// CHECK-SAME: [[NOTHING_ATTRS:#[0-9]+]]
// NO-OPT: ret i32 %_1.0
// NO-OPT: ret i32 4
// SIZE-OPT: ret i32 4
// SPEEC-OPT: ret i32 4
#[no_mangle]
Expand All @@ -18,7 +18,7 @@ pub fn nothing() -> i32 {

// CHECK-LABEL: define i32 @size
// CHECK-SAME: [[SIZE_ATTRS:#[0-9]+]]
// NO-OPT: ret i32 %_1.0
// NO-OPT: ret i32 6
// SIZE-OPT: ret i32 6
// SPEED-OPT: ret i32 6
#[optimize(size)]
Expand All @@ -31,7 +31,7 @@ pub fn size() -> i32 {
// NO-OPT-SAME: [[NOTHING_ATTRS]]
// SPEED-OPT-SAME: [[NOTHING_ATTRS]]
// SIZE-OPT-SAME: [[SPEED_ATTRS:#[0-9]+]]
// NO-OPT: ret i32 %_1.0
// NO-OPT: ret i32 8
// SIZE-OPT: ret i32 8
// SPEED-OPT: ret i32 8
#[optimize(speed)]
Expand Down
10 changes: 5 additions & 5 deletions src/test/incremental/hashes/while_let_loops.rs
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Expand Up @@ -48,7 +48,7 @@ pub fn change_loop_condition() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_loop_condition() {
let mut _x = 0;
Expand All @@ -70,7 +70,7 @@ pub fn add_break() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir, typeck_tables_of")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, typeck_tables_of")]
#[rustc_clean(cfg="cfail3")]
pub fn add_break() {
let mut _x = 0;
Expand Down Expand Up @@ -141,7 +141,7 @@ pub fn change_break_label() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_break_label() {
let mut _x = 0;
Expand Down Expand Up @@ -191,7 +191,7 @@ pub fn change_continue_label() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_continue_label() {
let mut _x = 0;
Expand All @@ -216,7 +216,7 @@ pub fn change_continue_to_break() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_continue_to_break() {
let mut _x = 0;
Expand Down
4 changes: 2 additions & 2 deletions src/test/incremental/hashes/while_loops.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ pub fn change_loop_condition() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_loop_condition() {
let mut _x = 0;
Expand Down Expand Up @@ -191,7 +191,7 @@ pub fn change_continue_label() {
}

#[cfg(not(cfail1))]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built, optimized_mir")]
#[rustc_clean(cfg="cfail2", except="HirBody, mir_built")]
#[rustc_clean(cfg="cfail3")]
pub fn change_continue_label() {
let mut _x = 0;
Expand Down