Auto merge of #131481 - nnethercote:rm-GenKillSet, r=cjgillot

Remove `GenKillAnalysis`

There are two kinds of dataflow analysis in the compiler: `Analysis`, which is the basic kind, and `GenKillAnalysis`, which is a more specialized kind for gen/kill analyses that is intended as an optimization. However, it turns out that `GenKillAnalysis` is actually a  pessimization! It's faster (and much simpler) to do all the gen/kill analyses via `Analysis`. This lets us remove `GenKillAnalysis`, and `GenKillSet`, and a few other things, and also merge `AnalysisDomain` into `Analysis`. The PR removes 500 lines of code and improves performance.

r? `@tmiasko`

1 files changed, 0 insertions, 7 deletions

diff --git a/compiler/rustc_middle/src/mir/basic_blocks.rs b/compiler/rustc_middle/src/mir/basic_blocks.rs
index 4602c918160..3eb563d7d6e 100644
--- a/compiler/rustc_middle/src/mir/basic_blocks.rs
+++ b/compiler/rustc_middle/src/mir/basic_blocks.rs
@@ -26,7 +26,6 @@ type SwitchSources = FxHashMap<(BasicBlock, BasicBlock), SmallVec<[Option<u128>;
 struct Cache {
     predecessors: OnceLock<Predecessors>,
     switch_sources: OnceLock<SwitchSources>,
-    is_cyclic: OnceLock<bool>,
     reverse_postorder: OnceLock<Vec<BasicBlock>>,
     dominators: OnceLock<Dominators<BasicBlock>>,
 }
@@ -37,12 +36,6 @@ impl<'tcx> BasicBlocks<'tcx> {
         BasicBlocks { basic_blocks, cache: Cache::default() }
     }
 
-    /// Returns true if control-flow graph contains a cycle reachable from the `START_BLOCK`.
-    #[inline]
-    pub fn is_cfg_cyclic(&self) -> bool {
-        *self.cache.is_cyclic.get_or_init(|| graph::is_cyclic(self))
-    }
-
     pub fn dominators(&self) -> &Dominators<BasicBlock> {
         self.cache.dominators.get_or_init(|| dominators(self))
     }