user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

[const-prop] Clean up check_cast() a bit

Browse source
This commit is contained in:
Wesley Wiser 2019-12-28 16:51:13 -05:00
parent 397a2fd744
commit 1886985380
1 changed files with 35 additions and 31 deletions
Download patch file Download diff file Expand all files Collapse all files

66
src/librustc_mir/transform/const_prop.rs
View file

@ -546,38 +546,42 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
source_info: SourceInfo,
place_layout: TyLayout<'tcx>,
) -> Option<()> {
if ty.is_integral() && op.ty(&self.local_decls, self.tcx).is_integral() {
let value = self.use_ecx(source_info, |this| {
this.ecx.read_immediate(this.ecx.eval_operand(op, None)?)
})?;
if !ty.is_integral() || !op.ty(&self.local_decls, self.tcx).is_integral() {
return Some(());
}
// Do not try to read bits for ZSTs
if !value.layout.is_zst() {
let value_size = value.layout.size;
let value_bits = value.to_scalar().and_then(|r| r.to_bits(value_size));
if let Ok(value_bits) = value_bits {
let truncated = truncate(value_bits, place_layout.size);
if truncated != value_bits {
let scope = source_info.scope;
let lint_root = match &self.source_scopes[scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
ClearCrossCrate::Clear => return None,
};
self.tcx.lint_hir(
::rustc::lint::builtin::CONST_ERR,
lint_root,
source_info.span,
&format!(
"truncating cast: the value {} requires {} bits but \
the target type is only {} bits",
value_bits,
value_size.bits(),
place_layout.size.bits()
),
);
return None;
}
}
let value = self.use_ecx(source_info, |this| {
this.ecx.read_immediate(this.ecx.eval_operand(op, None)?)
})?;
// Do not try to read bits for ZSTs
if value.layout.is_zst() {
return Some(());
}
let value_size = value.layout.size;
let value_bits = value.to_scalar().and_then(|r| r.to_bits(value_size));
if let Ok(value_bits) = value_bits {
let truncated = truncate(value_bits, place_layout.size);
if truncated != value_bits {
let scope = source_info.scope;
let lint_root = match &self.source_scopes[scope].local_data {
ClearCrossCrate::Set(data) => data.lint_root,
ClearCrossCrate::Clear => return None,
};
self.tcx.lint_hir(
::rustc::lint::builtin::CONST_ERR,
lint_root,
source_info.span,
&format!(
"truncating cast: the value {} requires {} bits but the target type is \
only {} bits",
value_bits,
value_size.bits(),
place_layout.size.bits()
),
);
return None;
}
}