From fcceef1838b09cffdc94eca97788b45a29e1299f Mon Sep 17 00:00:00 2001
From: Taras Tsugrii <taras.tsugriy@gmail.com>
Date: Mon, 7 Aug 2023 22:34:54 -0500
Subject: [PATCH] [perf] Reserve capacity for argvs.

This avoids unnecessary allocations to grow vector to sufficient size.
---
 src/tools/miri/src/eval.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/tools/miri/src/eval.rs b/src/tools/miri/src/eval.rs
index b761a6cf475..88e7d5386db 100644
--- a/src/tools/miri/src/eval.rs
+++ b/src/tools/miri/src/eval.rs
@@ -301,7 +301,7 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
     // Third argument (`argv`): created from `config.args`.
     let argv = {
         // Put each argument in memory, collect pointers.
-        let mut argvs = Vec::<Immediate<Provenance>>::new();
+        let mut argvs = Vec::<Immediate<Provenance>>::with_capacity(config.args.len());
         for arg in config.args.iter() {
             // Make space for `0` terminator.
             let size = u64::try_from(arg.len()).unwrap().checked_add(1).unwrap();