[lld] 5d928ff - [ELF] Remove error-prone RelocationBaseSection::classof

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2024-10-19T21:02:03-07:00
New Revision: 5d928ffce22d976b6594496f14351e00c2e4dd78

URL: https://github.com/llvm/llvm-project/commit/5d928ffce22d976b6594496f14351e00c2e4dd78
DIFF: https://github.com/llvm/llvm-project/commit/5d928ffce22d976b6594496f14351e00c2e4dd78.diff

LOG: [ELF] Remove error-prone RelocationBaseSection::classof

Added: 
    

Modified: 
    lld/ELF/OutputSections.cpp
    lld/ELF/SyntheticSections.h
    lld/ELF/Writer.cpp

Removed: 
    


################################################################################
diff  --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 6f76c5d73a5388..6cae7cf8f8599d 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -882,7 +882,11 @@ void OutputSection::checkDynRelAddends(Ctx &ctx) {
     // for input .rel[a].<sec> sections which we simply pass through to the
     // output. We skip over those and only look at the synthetic relocation
     // sections created during linking.
-    const auto *sec = dyn_cast<RelocationBaseSection>(sections[i]);
+    if (!SyntheticSection::classof(sections[i]) ||
+        !is_contained({ELF::SHT_REL, ELF::SHT_RELA, ELF::SHT_RELR},
+                      sections[i]->type))
+      return;
+    const auto *sec = cast<RelocationBaseSection>(sections[i]);
     if (!sec)
       return;
     for (const DynamicReloc &rel : sec->relocs) {

diff  --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index d64c4aad8c552b..3573767671feb1 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -547,13 +547,7 @@ class RelocationBaseSection : public SyntheticSection {
   void mergeRels();
   void partitionRels();
   void finalizeContents() override;
-  static bool classof(const SectionBase *d) {
-    return SyntheticSection::classof(d) &&
-           (d->type == llvm::ELF::SHT_RELA || d->type == llvm::ELF::SHT_REL ||
-            d->type == llvm::ELF::SHT_RELR ||
-            (d->type == llvm::ELF::SHT_AARCH64_AUTH_RELR &&
-             elf::ctx.arg.emachine == llvm::ELF::EM_AARCH64));
-  }
+
   int32_t dynamicTag, sizeDynamicTag;
   SmallVector<DynamicReloc, 0> relocs;
 

diff  --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 975954991caebe..ecd4f5e470833c 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -1690,10 +1690,9 @@ static void removeUnusedSyntheticSections(Ctx &ctx) {
         // finalizeAddressDependentContent, making .rela.dyn no longer empty.
         // Conservatively keep .rela.dyn. .relr.auth.dyn can be made empty, but
         // we would fail to remove it here.
-        if (ctx.arg.emachine == EM_AARCH64 && ctx.arg.relrPackDynRelocs)
-          if (auto *relSec = dyn_cast<RelocationBaseSection>(sec))
-            if (relSec == ctx.mainPart->relaDyn.get())
-              return false;
+        if (ctx.arg.emachine == EM_AARCH64 && ctx.arg.relrPackDynRelocs &&
+            sec == ctx.mainPart->relaDyn.get())
+          return false;
         unused.insert(sec);
         return true;
       });