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Simplify const propagator by removing unused code paths

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This commit is contained in:
Oliver Schneider 2018-01-30 14:28:45 +01:00
parent 411fcf58fd
commit 1561b4ad50
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GPG key ID: A69F8D225B3AD7D9
1 changed files with 52 additions and 71 deletions
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123
src/librustc_mir/transform/const_prop.rs
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@ -359,81 +359,62 @@ impl<'b, 'a, 'tcx> Visitor<'tcx> for ConstPropagator<'b, 'a, 'tcx> {
&mut self,
block: BasicBlock,
kind: &TerminatorKind<'tcx>,
_location: Location,
location: Location,
) {
match kind {
TerminatorKind::SwitchInt { discr: value, .. } |
TerminatorKind::Yield { value, .. } |
TerminatorKind::Assert { cond: value, .. } => {
match value {
Operand::Constant(box Constant {
literal: Literal::Value {
value: &ty::Const {
val: ConstVal::Value(_),
..
},
},
..
}) => return,
_ => {},
}
if let Some(value) = self.eval_operand(value) {
if let TerminatorKind::Assert { expected, msg, .. } = kind {
if Value::ByVal(PrimVal::from_bool(*expected)) != value.0 {
let span = self.mir[block]
.terminator
.as_ref()
.unwrap()
.source_info
.span;
let node_id = self
.tcx
.hir
.as_local_node_id(self.source.def_id)
.expect("some part of a failing const eval must be local");
let mut lint = self.tcx.struct_span_lint_node(
::rustc::lint::builtin::CONST_ERR,
node_id,
self.super_terminator_kind(block, kind, location);
if let TerminatorKind::Assert { expected, msg, cond, .. } = kind {
if let Some(value) = self.eval_operand(cond) {
if Value::ByVal(PrimVal::from_bool(*expected)) != value.0 {
let span = self.mir[block]
.terminator
.as_ref()
.unwrap()
.source_info
.span;
let node_id = self
.tcx
.hir
.as_local_node_id(self.source.def_id)
.expect("some part of a failing const eval must be local");
let mut lint = self.tcx.struct_span_lint_node(
::rustc::lint::builtin::CONST_ERR,
node_id,
span,
"constant evaluation error",
);
use rustc::mir::AssertMessage::*;
match msg {
GeneratorResumedAfterReturn =>
lint.span_label(span, "generator resumed after completion"),
GeneratorResumedAfterPanic =>
lint.span_label(span, "generator resumed after panicking"),
Math(ref err) => lint.span_label(span, err.description()),
BoundsCheck { ref len, ref index } => {
let len = self.eval_operand(len).expect("len must be const");
let len = match len.0 {
Value::ByVal(PrimVal::Bytes(n)) => n,
_ => bug!("const len not primitive: {:?}", len),
};
let index = self
.eval_operand(index)
.expect("index must be const");
let index = match index.0 {
Value::ByVal(PrimVal::Bytes(n)) => n,
_ => bug!("const index not primitive: {:?}", index),
};
lint.span_label(
span,
"constant evaluation error",
);
use rustc::mir::AssertMessage::*;
match msg {
GeneratorResumedAfterReturn =>
lint.span_label(span, "generator resumed after completion"),
GeneratorResumedAfterPanic =>
lint.span_label(span, "generator resumed after panicking"),
Math(ref err) => lint.span_label(span, err.description()),
BoundsCheck { ref len, ref index } => {
let len = self.eval_operand(len).expect("len must be const");
let len = match len.0 {
Value::ByVal(PrimVal::Bytes(n)) => n,
_ => bug!("const len not primitive: {:?}", len),
};
let index = self
.eval_operand(index)
.expect("index must be const");
let index = match index.0 {
Value::ByVal(PrimVal::Bytes(n)) => n,
_ => bug!("const index not primitive: {:?}", index),
};
lint.span_label(
span,
format!(
"index out of bounds: \
the len is {} but the index is {}",
len,
index,
),
)
},
}.emit();
}
}
format!(
"index out of bounds: \
the len is {} but the index is {}",
len,
index,
),
)
},
}.emit();
}
}
// FIXME: do this optimization for function calls
_ => {},
}
}
}