Reserve new_blocks once.

cjgillot · cjgillot · commit ac9e3c4d4ed4 · 2025-10-08T19:01:27.000Z
diff --git a/compiler/rustc_mir_transform/src/add_call_guards.rs b/compiler/rustc_mir_transform/src/add_call_guards.rs
@@ -82,7 +82,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {
         }
 
         // We need a place to store the new blocks generated
-        let mut new_blocks = Vec::new();
+        let mut new_blocks = Vec::with_capacity(work.len());
 
         let cur_len = body.basic_blocks.len();
         let mut new_block = |source_info: SourceInfo, is_cleanup: bool, target: BasicBlock| {

Original file line number	Diff line number	Diff line change
`@@ -82,7 +82,7 @@ impl<'tcx> crate::MirPass<'tcx> for AddCallGuards {`
`82`	`82`	`}`
`83`	`83`
`84`	`84`	`// We need a place to store the new blocks generated`
`85`		`- let mut new_blocks = Vec::new();`
	`85`	`+ let mut new_blocks = Vec::with_capacity(work.len());`
`86`	`86`
`87`	`87`	`let cur_len = body.basic_blocks.len();`
`88`	`88`	`let mut new_block = \|source_info: SourceInfo, is_cleanup: bool, target: BasicBlock\| {`