From f5ef9bd26d531d104f44f9e5b283bd2f80c024be Mon Sep 17 00:00:00 2001
From: Kazu Hirata <kazu@google.com>
Date: Thu, 21 Mar 2024 11:17:52 -0700
Subject: [PATCH] [memprof] Call SmallVector::reserve (#86055)

With one raw memprof file I have, NumPCs averages about 41.  Given the
default number of inline elements being 8 for SmallVector<uint64_t>,
we should reserve the storage in advance.
---
 llvm/lib/ProfileData/RawMemProfReader.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/llvm/lib/ProfileData/RawMemProfReader.cpp b/llvm/lib/ProfileData/RawMemProfReader.cpp
index 0e2b8668bab7..60c37c417aa0 100644
--- a/llvm/lib/ProfileData/RawMemProfReader.cpp
+++ b/llvm/lib/ProfileData/RawMemProfReader.cpp
@@ -127,6 +127,7 @@ CallStackMap readStackInfo(const char *Ptr) {
         endian::readNext<uint64_t, llvm::endianness::little, unaligned>(Ptr);
 
     SmallVector<uint64_t> CallStack;
+    CallStack.reserve(NumPCs);
     for (uint64_t J = 0; J < NumPCs; J++) {
       CallStack.push_back(
           endian::readNext<uint64_t, llvm::endianness::little, unaligned>(Ptr));