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incr.comp.: Fix Span hashing in various ways #46301

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incr.comp.: Fix Span hashing in various ways #46301

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b28e036
incr.comp.: Properly hash and encode macro expansion information.
michaelwoerister Nov 22, 2017
faca970
incr.comp.: Store Spans as (file,line,col,length) in incr.comp. cache.
michaelwoerister Nov 24, 2017
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77 changes: 33 additions & 44 deletions src/librustc/ich/hcx.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ use syntax::attr;
use syntax::codemap::CodeMap;
use syntax::ext::hygiene::SyntaxContext;
use syntax::symbol::Symbol;
use syntax_pos::Span;
use syntax_pos::{Span, DUMMY_SP};

use rustc_data_structures::stable_hasher::{HashStable, StableHashingContextProvider,
StableHasher, StableHasherResult,
Expand Down Expand Up @@ -362,64 +362,53 @@ impl<'gcx> HashStable<StableHashingContext<'gcx>> for Span {
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
hasher: &mut StableHasher<W>) {
use syntax_pos::Pos;
const TAG_VALID_SPAN: u8 = 0;
const TAG_INVALID_SPAN: u8 = 1;
const TAG_EXPANSION: u8 = 0;
const TAG_NO_EXPANSION: u8 = 1;

if !hcx.hash_spans {
return
}

if *self == DUMMY_SP {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}

// If this is not an empty or invalid span, we want to hash the last
// position that belongs to it, as opposed to hashing the first
// position past it.
let span = self.data();
let span_hi = if span.hi > span.lo {
// We might end up in the middle of a multibyte character here,
// but that's OK, since we are not trying to decode anything at
// this position.
span.hi - ::syntax_pos::BytePos(1)
} else {
span.hi
};

{
let loc1 = hcx.codemap().byte_pos_to_line_and_col(span.lo);
let loc1 = loc1.as_ref()
.map(|&(ref fm, line, col)| (&fm.name[..], line, col.to_usize()))
.unwrap_or(("???", 0, 0));

let loc2 = hcx.codemap().byte_pos_to_line_and_col(span_hi);
let loc2 = loc2.as_ref()
.map(|&(ref fm, line, col)| (&fm.name[..], line, col.to_usize()))
.unwrap_or(("???", 0, 0));

if loc1.0 == loc2.0 {
std_hash::Hash::hash(&0u8, hasher);

std_hash::Hash::hash(loc1.0, hasher);
std_hash::Hash::hash(&loc1.1, hasher);
std_hash::Hash::hash(&loc1.2, hasher);

// Do not hash the file name twice
std_hash::Hash::hash(&loc2.1, hasher);
std_hash::Hash::hash(&loc2.2, hasher);
} else {
std_hash::Hash::hash(&1u8, hasher);

std_hash::Hash::hash(loc1.0, hasher);
std_hash::Hash::hash(&loc1.1, hasher);
std_hash::Hash::hash(&loc1.2, hasher);

std_hash::Hash::hash(loc2.0, hasher);
std_hash::Hash::hash(&loc2.1, hasher);
std_hash::Hash::hash(&loc2.2, hasher);
if span.hi < span.lo {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
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I wonder why we generate so many invalid spans... how confident are you that these don't show up in diagnostics etc? I am not that confident. =) Are there asserts testing that hypothesis?

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What gives me some confidence is that the output would be unreadable. That is, such spans span multiple file so displaying one of them in diagnostics would show two partial files and a random number of unrelated files that happen to be located in between the two initial files in the codemap. I haven't seen something like that yet.

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I dimly recall adding some asserts of this kind in the code that generates snippets and things, though I can't find that now.

}

let (file_lo, line_lo, col_lo) = match hcx.codemap()
.byte_pos_to_line_and_col(span.lo) {
Some(pos) => pos,
None => {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}
};

if !file_lo.contains(span.hi) {
return std_hash::Hash::hash(&TAG_INVALID_SPAN, hasher);
}

let len = span.hi - span.lo;

std_hash::Hash::hash(&TAG_VALID_SPAN, hasher);
std_hash::Hash::hash(&file_lo.name, hasher);
std_hash::Hash::hash(&line_lo, hasher);
std_hash::Hash::hash(&col_lo, hasher);
std_hash::Hash::hash(&len, hasher);

if span.ctxt == SyntaxContext::empty() {
0u8.hash_stable(hcx, hasher);
TAG_NO_EXPANSION.hash_stable(hcx, hasher);
} else {
1u8.hash_stable(hcx, hasher);
self.source_callsite().hash_stable(hcx, hasher);
TAG_EXPANSION.hash_stable(hcx, hasher);
span.ctxt.outer().expn_info().hash_stable(hcx, hasher);
}
}
}
Expand Down
24 changes: 24 additions & 0 deletions src/librustc/ich/impls_syntax.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -347,6 +347,30 @@ impl_stable_hash_for!(enum ::syntax::ast::MetaItemKind {
NameValue(lit)
});

impl_stable_hash_for!(struct ::syntax_pos::hygiene::ExpnInfo {
call_site,
callee
});

impl_stable_hash_for!(struct ::syntax_pos::hygiene::NameAndSpan {
format,
allow_internal_unstable,
allow_internal_unsafe,
span
});

impl_stable_hash_for!(enum ::syntax_pos::hygiene::ExpnFormat {
MacroAttribute(sym),
MacroBang(sym),
CompilerDesugaring(kind)
});

impl_stable_hash_for!(enum ::syntax_pos::hygiene::CompilerDesugaringKind {
BackArrow,
DotFill,
QuestionMark
});

impl<'gcx> HashStable<StableHashingContext<'gcx>> for FileMap {
fn hash_stable<W: StableHasherResult>(&self,
hcx: &mut StableHashingContext<'gcx>,
Expand Down
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