[llvm] [nfc][InstrProfWriter]Store header fields in a vector and back patch once (PR #93594)

[Mingming Liu via llvm-commits]

https://github.com/minglotus-6 created https://github.com/llvm/llvm-project/pull/93594

This is a split of https://github.com/llvm/llvm-project/pull/93346 as discussed.

>From 40e9da556ed0cb619d6312b814853ff58c60fce4 Mon Sep 17 00:00:00 2001
From: mingmingl <mingmingl at google.com>
Date: Tue, 28 May 2024 11:21:26 -0700
Subject: [PATCH] [nfc][InstrProfWriter]Store header fields in a vector and
 back patch once

---
 llvm/lib/ProfileData/InstrProfWriter.cpp | 62 ++++++------------------
 1 file changed, 16 insertions(+), 46 deletions(-)

diff --git a/llvm/lib/ProfileData/InstrProfWriter.cpp b/llvm/lib/ProfileData/InstrProfWriter.cpp
index b67a9700b680a..beb73da0dc3ba 100644
--- a/llvm/lib/ProfileData/InstrProfWriter.cpp
+++ b/llvm/lib/ProfileData/InstrProfWriter.cpp
@@ -841,52 +841,22 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
   }
   InfoObj->CSSummaryBuilder = nullptr;
 
-  const size_t MemProfOffset = BackPatchStartOffset + sizeof(uint64_t);
-  const size_t BinaryIdOffset = MemProfOffset + sizeof(uint64_t);
-  const size_t TemporalProfTracesOffset = BinaryIdOffset + sizeof(uint64_t);
-  const size_t VTableNamesOffset = TemporalProfTracesOffset + sizeof(uint64_t);
-  if (!WritePrevVersion) {
-    // Now do the final patch:
-    PatchItem PatchItems[] = {
-        // Patch the Header.HashOffset field.
-        {BackPatchStartOffset, &HashTableStart, 1},
-        // Patch the Header.MemProfOffset (=0 for profiles without MemProf
-        // data).
-        {MemProfOffset, &MemProfSectionStart, 1},
-        // Patch the Header.BinaryIdSectionOffset.
-        {BinaryIdOffset, &BinaryIdSectionStart, 1},
-        // Patch the Header.TemporalProfTracesOffset (=0 for profiles without
-        // traces).
-        {TemporalProfTracesOffset, &TemporalProfTracesSectionStart, 1},
-        {VTableNamesOffset, &VTableNamesSectionStart, 1},
-        // Patch the summary data.
-        {SummaryOffset, reinterpret_cast<uint64_t *>(TheSummary.get()),
-         (int)(SummarySize / sizeof(uint64_t))},
-        {CSSummaryOffset, reinterpret_cast<uint64_t *>(TheCSSummary.get()),
-         (int)CSSummarySize}};
-
-    OS.patch(PatchItems);
-  } else {
-    // Now do the final patch:
-    PatchItem PatchItems[] = {
-        // Patch the Header.HashOffset field.
-        {BackPatchStartOffset, &HashTableStart, 1},
-        // Patch the Header.MemProfOffset (=0 for profiles without MemProf
-        // data).
-        {MemProfOffset, &MemProfSectionStart, 1},
-        // Patch the Header.BinaryIdSectionOffset.
-        {BinaryIdOffset, &BinaryIdSectionStart, 1},
-        // Patch the Header.TemporalProfTracesOffset (=0 for profiles without
-        // traces).
-        {TemporalProfTracesOffset, &TemporalProfTracesSectionStart, 1},
-        // Patch the summary data.
-        {SummaryOffset, reinterpret_cast<uint64_t *>(TheSummary.get()),
-         (int)(SummarySize / sizeof(uint64_t))},
-        {CSSummaryOffset, reinterpret_cast<uint64_t *>(TheCSSummary.get()),
-         (int)CSSummarySize}};
-
-    OS.patch(PatchItems);
-  }
+  SmallVector<uint64_t, 8> HeaderOffsets = {HashTableStart, MemProfSectionStart,
+                                            BinaryIdSectionStart,
+                                            TemporalProfTracesSectionStart};
+  if (!WritePrevVersion)
+    HeaderOffsets.push_back(VTableNamesSectionStart);
+
+  PatchItem PatchItems[] = {
+      // Patch the Header fields
+      {BackPatchStartOffset, HeaderOffsets.data(), (int)HeaderOffsets.size()},
+      // Patch the summary data.
+      {SummaryOffset, reinterpret_cast<uint64_t *>(TheSummary.get()),
+       (int)(SummarySize / sizeof(uint64_t))},
+      {CSSummaryOffset, reinterpret_cast<uint64_t *>(TheCSSummary.get()),
+       (int)CSSummarySize}};
+
+  OS.patch(PatchItems);
 
   for (const auto &I : FunctionData)
     for (const auto &F : I.getValue())