[PATCH] D72194: [MC][ELF] Ensure that mergeable globals with an explicit section are assigned to SHF_MERGE sections with compatible entsizes

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

> The basic mechanism is to create multiple sections with the same name, using LLVM's ", unique," assembly extension (I refer to such sections as unique/uniqued sections) if incompatible symbols are explicitly given the same section name.

unique linkage. `assembly extension` can be deleted because GNU as>=2.35 supports it as well.

>   Update: There will be a similar issue for associated symbols once https://reviews.llvm.org/D74006 lands.

This sentence can be deleted now.

> Symbols with a an explicit assignment

`a an` -> an

The summary is very long. Can you simplify it?



================
Comment at: llvm/include/llvm/MC/MCContext.h:318
+        if ((Flags & ELF::SHF_STRINGS) != (Other.Flags & ELF::SHF_STRINGS))
+          return (Other.Flags & ELF::SHF_STRINGS);
+        return EntrySize < Other.EntrySize;
----------------
excess parentheses


================
Comment at: llvm/include/llvm/MC/MCContext.h:327
+    // sizes. This can occur when a symbol is explicitly assigned to a
+    // section, e.g. via _attribute_((section("myname"))).
+    std::map<ELFEntrySizeKey, unsigned> ELFEntrySizeMap;
----------------
`__attribute__`


================
Comment at: llvm/include/llvm/MC/MCContext.h:335
+    // sections (e.g. via _attribute_((section("myname")))).
+    std::set<StringRef> ELFSeenGenericMergeableSections;
+
----------------
DenseSet


================
Comment at: llvm/lib/MC/MCContext.cpp:452
+  bool IsMergeable = Flags & ELF::SHF_MERGE;
+  bool IsGenericSection = UniqueID == GenericSectionID;
+
----------------
The variable IsGenericSection can be omitted.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72194/new/

https://reviews.llvm.org/D72194