Auto merge of #108062 - Zoxc:spec-incr, r=cjgillot

Specialize query execution for incremental and non-incremental

This specializes query execution for incremental and non-incremental by passing in a separate `dyn QueryEngine` types, taking advantage of the virtual dispatch to avoid a branch. This ends up duplicating `try_execute_query`, hopefully the compile time cost of that is relatively low.

This is a performance improvement for the non-incremental path:
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check</td><td align="right">1.8420s</td><td align="right">1.8331s</td><td align="right"> -0.48%</td></tr><tr><td>🟣 <b>hyper</b>:check</td><td align="right">0.2652s</td><td align="right">0.2631s</td><td align="right"> -0.78%</td></tr><tr><td>🟣 <b>regex</b>:check</td><td align="right">1.0161s</td><td align="right">1.0062s</td><td align="right"> -0.98%</td></tr><tr><td>🟣 <b>syn</b>:check</td><td align="right">1.6408s</td><td align="right">1.6197s</td><td align="right">💚  -1.28%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check</td><td align="right">6.3939s</td><td align="right">6.3558s</td><td align="right"> -0.60%</td></tr><tr><td>Total</td><td align="right">11.1580s</td><td align="right">11.0780s</td><td align="right"> -0.72%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9918s</td><td align="right"> -0.82%</td></tr></table>

The incremental path is more neutral:
<table><tr><td rowspan="2">Benchmark</td><td colspan="1"><b>Before</b></th><td colspan="2"><b>After</b></th></tr><tr><td align="right">Time</td><td align="right">Time</td><td align="right">%</th></tr><tr><td>🟣 <b>clap</b>:check:initial</td><td align="right">2.2210s</td><td align="right">2.2227s</td><td align="right"> 0.08%</td></tr><tr><td>🟣 <b>hyper</b>:check:initial</td><td align="right">0.3441s</td><td align="right">0.3443s</td><td align="right"> 0.05%</td></tr><tr><td>🟣 <b>regex</b>:check:initial</td><td align="right">1.2919s</td><td align="right">1.2877s</td><td align="right"> -0.33%</td></tr><tr><td>🟣 <b>syn</b>:check:initial</td><td align="right">2.0749s</td><td align="right">2.0721s</td><td align="right"> -0.14%</td></tr><tr><td>🟣 <b>syntex_syntax</b>:check:initial</td><td align="right">7.9266s</td><td align="right">7.9206s</td><td align="right"> -0.07%</td></tr><tr><td>Total</td><td align="right">13.8585s</td><td align="right">13.8474s</td><td align="right"> -0.08%</td></tr><tr><td>Summary</td><td align="right">1.0000s</td><td align="right">0.9992s</td><td align="right"> -0.08%</td></tr></table>

r? `@cjgillot`

compiler/rustc_query_impl/src/lib.rs

@@ -34,7 +34,8 @@ use rustc_middle::ty::TyCtxt;
 use rustc_query_system::dep_graph::SerializedDepNodeIndex;
 use rustc_query_system::ich::StableHashingContext;
 use rustc_query_system::query::{
-    get_query, HashResult, QueryCache, QueryConfig, QueryInfo, QueryMap, QueryMode, QueryState,
+    get_query_incr, get_query_non_incr, HashResult, QueryCache, QueryConfig, QueryInfo, QueryMap,
+    QueryMode, QueryState,
 };
 use rustc_query_system::HandleCycleError;
 use rustc_query_system::Value;
@@ -203,6 +204,7 @@ pub fn query_system<'tcx>(
     local_providers: Providers,
     extern_providers: ExternProviders,
     on_disk_cache: Option<OnDiskCache<'tcx>>,
+    incremental: bool,
 ) -> QuerySystem<'tcx> {
     QuerySystem {
         states: Default::default(),
@@ -211,7 +213,7 @@ pub fn query_system<'tcx>(
         dynamic_queries: dynamic_queries(),
         on_disk_cache,
         fns: QuerySystemFns {
-            engine: engine(),
+            engine: engine(incremental),
             local_providers,
             extern_providers,
             query_structs: make_dep_kind_array!(query_structs).to_vec(),