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Don't recompile Rust when only debug_info changes.
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Recent improvements of the self-profiler infrastructure caused
regression in Rust compilation times.  We now store detailed debug
info with each arrangement, including the list of source code locations
where the arrangement is used.  Every time the user as much as changes
the formatting in one of these locations, debug info changes causing the
crate that declares the relation to recompile.  The workaround is to
generate arrangements without debug_info and inject debug info from the
root crate, which always gets re-compiled anyway.

Signed-off-by: Leonid Ryzhyk <[email protected]>
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ryzhyk committed Dec 13, 2021
1 parent 875a937 commit e65559c
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6 changes: 6 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).

## [Unreleased]

### Quality-of-life improvements

- Avoid recompiling Rust crates when only arrangement debug info changes.

## [1.2.2] - Dec 9, 2021

### Bug fixes
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13 changes: 13 additions & 0 deletions rust/template/differential_datalog/src/program/mod.rs
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Expand Up @@ -866,6 +866,19 @@ impl Arrangement {
}
}

pub fn set_debug_info(mut self, dbg_info: ArrangementDebugInfo) -> Self {
match self {
Self::Map {
ref mut debug_info, ..
} => *debug_info = dbg_info,
Self::Set {
ref mut debug_info, ..
} => *debug_info = dbg_info,
};

self
}

fn build_arrangement_root<S>(
&self,
render_context: &RenderContext,
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45 changes: 27 additions & 18 deletions src/Language/DifferentialDatalog/Compile.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -2017,11 +2017,12 @@ compileRelation d statics rn = do
then "change_cb: ::core::option::Option::Some(::std::sync::Arc::clone(&__update_cb)),"
else "change_cb: ::core::option::Option::None,"
arrangements <- gets $ (M.! rn) . cArrangements
let compiled_arrangements = mapIdx (\arng i ->
let ?statics = moduleStatics statics (nameScope rel) in
let arng' = mkArrangement d rel arng in
"pub static" <+> arng_name i <+> ": ::once_cell::sync::Lazy<program::Arrangement> = ::once_cell::sync::Lazy::new(|| {" $$ nest' arng' $$ "});") arrangements

let (compiled_arrangements, arng_dbg_info) = unzip
$ mapIdx (\arng i ->
let ?statics = moduleStatics statics (nameScope rel) in
let (arng', dbginfo) = mkArrangement d rel arng in
("pub static" <+> arng_name i <+> ": ::once_cell::sync::Lazy<program::Arrangement> = ::once_cell::sync::Lazy::new(|| {" $$ nest' arng' $$ "});", dbginfo))
arrangements
let code =
"let" <+> rnameFlat rn <+> "=" <+> "::differential_datalog::program::Relation {"
$$ " name:" <+> cow_str rn <> ","
Expand All @@ -2040,7 +2041,7 @@ compileRelation d statics rn = do
$$ (nest' $ nest' $ vcat $ mapIdx (\rule i -> ridentScoped Nothing (ruleModule rule) (render $ rule_name i) <> ".clone(),") rules)
$$ " ],"
$$ " arrangements: vec!["
$$ (nest' $ nest' $ vcat $ mapIdx (\_ i -> (pp $ ridentScoped Nothing (nameScope rel) (render $ arng_name i)) <> ".clone(),") arrangements)
$$ (nest' $ nest' $ vcat $ mapIdx (\dbg_info i -> (pp $ ridentScoped Nothing (nameScope rel) (render $ arng_name i)) <> ".clone().set_debug_info(" <> dbg_info <> "),") arng_dbg_info)
$$ " ],"
$$ (nest' cb)
$$ "};"
Expand Down Expand Up @@ -2904,17 +2905,24 @@ mkNode (ApplyNode mname i xformer_name source_pos _) =
" tfun:" <+> ridentScoped Nothing mname ("__apply_" ++ show i) $$
"}"

mkArrangement :: (?cfg::Config, ?statics::CrateStatics, ?crate_graph::CrateGraph, ?specname::String, ?module_paths::ModulePathMap) => DatalogProgram -> Relation -> Arrangement -> Doc
-- Returns 'program::Arrangement' instance with empty 'debug_info' field, and
-- the actual 'debug_info' as a separate string. The former is placed in the
-- module that declares the relation; the latter is kept in the main module and
-- added when instantiating the program. This way the relation declaration (and
-- the crate it belongs to) don't need to be recompiled every time 'debug_info'
-- changes (since debug_info includes line numbers, it changes often).
mkArrangement :: (?cfg::Config, ?statics::CrateStatics, ?crate_graph::CrateGraph, ?specname::String, ?module_paths::ModulePathMap) => DatalogProgram -> Relation -> Arrangement -> (Doc, Doc)
mkArrangement d rel ArrangementMap{..} =
let filter_key = mkArrangementKey d rel arngPattern False
afun = braces' $
"let __cloned =" <+> vALUE_VAR <> ".clone();" $$
"let __cloned =" <+> vALUE_VAR <> ".clone();" $$
filter_key <> ".map(|x|(x,__cloned))"
in "program::Arrangement::Map{" $$
" debug_info:" <+> dbgInfoArrangement arngPattern arngUsedAt arngIndexes <> "," $$
(nest' $ "afun: {fn __f(" <> vALUE_VAR <> ": ::differential_datalog::ddval::DDValue) -> ::std::option::Option<(::differential_datalog::ddval::DDValue,::differential_datalog::ddval::DDValue)>" $$ afun $$ "__f},") $$
" queryable:" <+> (if null arngIndexes then "false" else "true") $$
"}"
in ("program::Arrangement::Map{" $$
" debug_info: Default::default()," $$
(nest' $ "afun: {fn __f(" <> vALUE_VAR <> ": ::differential_datalog::ddval::DDValue) -> ::std::option::Option<(::differential_datalog::ddval::DDValue,::differential_datalog::ddval::DDValue)>" $$ afun $$ "__f},") $$
" queryable:" <+> (if null arngIndexes then "false" else "true") $$
"}",
dbgInfoArrangement arngPattern arngUsedAt arngIndexes)

mkArrangement d rel ArrangementSet{..} =
let filter_key = mkArrangementKey d rel arngPattern False
Expand All @@ -2924,11 +2932,12 @@ mkArrangement d rel ArrangementSet{..} =
-- it if it is defined over all fields of a distinct relation (i.e.,
-- the pattern expression does not contain placeholders).
distinct_by_construction = relIsDistinct d rel && (not $ exprContainsPHolders arngPattern)
in "program::Arrangement::Set{" $$
" debug_info:" <+> dbgInfoArrangement arngPattern arngUsedAt [] <> "," $$
(nest' $ "fmfun: {fn __f(" <> vALUE_VAR <> ": ::differential_datalog::ddval::DDValue) -> ::std::option::Option<::differential_datalog::ddval::DDValue>" $$ fmfun $$ "__f},") $$
" distinct:" <+> (if arngDistinct && not distinct_by_construction then "true" else "false") $$
"}"
in ("program::Arrangement::Set{" $$
" debug_info: Default::default()," $$
(nest' $ "fmfun: {fn __f(" <> vALUE_VAR <> ": ::differential_datalog::ddval::DDValue) -> ::std::option::Option<::differential_datalog::ddval::DDValue>" $$ fmfun $$ "__f},") $$
" distinct:" <+> (if arngDistinct && not distinct_by_construction then "true" else "false") $$
"}",
dbgInfoArrangement arngPattern arngUsedAt [])

-- Generate part of the arrangement computation that filters inputs and computes the key part of the
-- arrangement.
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