[PATCH] D91018: [ELF] Make InputSection smaller

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 303906.
MaskRay edited the summary of this revision.
MaskRay added a comment.

Fix Windows


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D91018/new/

https://reviews.llvm.org/D91018

Files:
  lld/ELF/InputSection.h


Index: lld/ELF/InputSection.h
===================================================================
--- lld/ELF/InputSection.h
+++ lld/ELF/InputSection.h
@@ -52,15 +52,15 @@
   // this but instead this->Repl.
   SectionBase *repl;
 
-  unsigned sectionKind : 3;
+  uint8_t sectionKind : 3;
 
   // The next two bit fields are only used by InputSectionBase, but we
   // put them here so the struct packs better.
 
-  unsigned bss : 1;
+  uint8_t bss : 1;
 
   // Set for sections that should not be folded by ICF.
-  unsigned keepUnique : 1;
+  uint8_t keepUnique : 1;
 
   // The 1-indexed partition that this section is assigned to by the garbage
   // collector, or 0 if this section is dead. Normally there is only one
@@ -134,6 +134,10 @@
   // and shrinking a section.
   unsigned bytesDropped = 0;
 
+  // Whether the section needs to be padded with a NOP filler due to
+  // deleteFallThruJmpInsn.
+  bool nopFiller = false;
+
   void drop_back(uint64_t num) { bytesDropped += num; }
 
   void push_back(uint64_t num) {
@@ -210,17 +214,13 @@
   // The native ELF reloc data type is not very convenient to handle.
   // So we convert ELF reloc records to our own records in Relocations.cpp.
   // This vector contains such "cooked" relocations.
-  std::vector<Relocation> relocations;
-
-  // Indicates that this section needs to be padded with a NOP filler if set to
-  // true.
-  bool nopFiller = false;
+  SmallVector<Relocation, 0> relocations;
 
   // These are modifiers to jump instructions that are necessary when basic
   // block sections are enabled.  Basic block sections creates opportunities to
   // relax jump instructions at basic block boundaries after reordering the
   // basic blocks.
-  std::vector<JumpInstrMod> jumpInstrMods;
+  SmallVector<JumpInstrMod, 0> jumpInstrMods;
 
   // A function compiled with -fsplit-stack calling a function
   // compiled without -fsplit-stack needs its prologue adjusted. Find
@@ -390,6 +390,8 @@
   template <class ELFT> void copyShtGroup(uint8_t *buf);
 };
 
+static_assert(sizeof(InputSection) <= 184, "InputSection is too big");
+
 inline bool isDebugSection(const InputSectionBase &sec) {
   return sec.name.startswith(".debug") || sec.name.startswith(".zdebug");
 }


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