[llvm] Bitcode: Stop combining function alignments into MaxAlignment. (PR #155341)

[Peter Collingbourne via llvm-commits]

https://github.com/pcc created https://github.com/llvm/llvm-project/pull/155341

MaxAlignment is used to produce the abbreviation for MODULE_CODE_GLOBALVAR
and is not used for anything related to function alignments, so stop
combining function alignments and rename it to make its purpose clearer.


>From 72a0e2c222d1f5dd70232bd2706451f283f4c00b Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter at pcc.me.uk>
Date: Mon, 25 Aug 2025 18:50:41 -0700
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.6-beta.1
---
 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index a3f825408d0c2..a1d5b36bde64d 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1495,14 +1495,11 @@ void ModuleBitcodeWriter::writeModuleInfo() {
   // compute the maximum alignment value.
   std::map<std::string, unsigned> SectionMap;
   std::map<std::string, unsigned> GCMap;
-  MaybeAlign MaxAlignment;
+  MaybeAlign MaxGVarAlignment;
   unsigned MaxGlobalType = 0;
-  const auto UpdateMaxAlignment = [&MaxAlignment](const MaybeAlign A) {
-    if (A)
-      MaxAlignment = !MaxAlignment ? *A : std::max(*MaxAlignment, *A);
-  };
   for (const GlobalVariable &GV : M.globals()) {
-    UpdateMaxAlignment(GV.getAlign());
+    if (MaybeAlign A = GV.getAlign())
+      MaxGVarAlignment = !MaxGVarAlignment ? *A : std::max(*MaxGVarAlignment, *A);
     MaxGlobalType = std::max(MaxGlobalType, VE.getTypeID(GV.getValueType()));
     if (GV.hasSection()) {
       // Give section names unique ID's.
@@ -1515,7 +1512,6 @@ void ModuleBitcodeWriter::writeModuleInfo() {
     }
   }
   for (const Function &F : M) {
-    UpdateMaxAlignment(F.getAlign());
     if (F.hasSection()) {
       // Give section names unique ID's.
       unsigned &Entry = SectionMap[std::string(F.getSection())];
@@ -1551,10 +1547,10 @@ void ModuleBitcodeWriter::writeModuleInfo() {
                                                            //| constant
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));   // Initializer.
     Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 5)); // Linkage.
-    if (!MaxAlignment)                                     // Alignment.
+    if (!MaxGVarAlignment)                                 // Alignment.
       Abbv->Add(BitCodeAbbrevOp(0));
     else {
-      unsigned MaxEncAlignment = getEncodedAlign(MaxAlignment);
+      unsigned MaxEncAlignment = getEncodedAlign(MaxGVarAlignment);
       Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed,
                                Log2_32_Ceil(MaxEncAlignment+1)));
     }