[lld] r268644 - Reuse logic for deciding whether to keep a local symbol or not.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Thu May  5 11:38:46 2016
New Revision: 268644

URL: http://llvm.org/viewvc/llvm-project?rev=268644&view=rev
Log:
Reuse logic for deciding whether to keep a local symbol or not.

Modified:
    lld/trunk/ELF/Writer.cpp
    lld/trunk/test/ELF/string-gc.s

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=268644&r1=268643&r2=268644&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Thu May  5 11:38:46 2016
@@ -832,6 +832,8 @@ static bool shouldKeepInSymtab(InputSect
   return !(Sec->getSectionHdr()->sh_flags & SHF_MERGE);
 }
 
+template <class ELFT> static bool includeInSymtab(const SymbolBody &B);
+
 // Local symbols are not in the linker's symbol table. This function scans
 // each object file's symbol table to copy local symbols to the output.
 template <class ELFT> void Writer<ELFT>::copyLocalSymbols() {
@@ -845,23 +847,12 @@ template <class ELFT> void Writer<ELFT>:
       // No reason to keep local undefined symbol in symtab.
       if (!DR)
         continue;
+      if (!includeInSymtab<ELFT>(*B))
+        continue;
       StringRef SymName(StrTab + B->getNameOffset());
       InputSectionBase<ELFT> *Sec = DR->Section;
       if (!shouldKeepInSymtab<ELFT>(Sec, SymName, *B))
         continue;
-      if (Sec) {
-        if (!Sec->Live)
-          continue;
-
-        // Garbage collection is normally able to remove local symbols if they
-        // point to gced sections. In the case of SHF_MERGE sections, we want it
-        // to also be able to drop them if part of the section is gced.
-        // We could look at the section offset map to keep some of these
-        // symbols, but almost all local symbols are .L* symbols, so it
-        // is probably not worth the complexity.
-        if (Config->GcSections && isa<MergeInputSection<ELFT>>(Sec))
-          continue;
-      }
       ++Out<ELFT>::SymTab->NumLocals;
       if (Config->Relocatable)
         B->DynsymIndex = Out<ELFT>::SymTab->NumLocals;
@@ -1114,7 +1105,7 @@ template <class ELFT> void Writer<ELFT>:
 }
 
 template <class ELFT> static bool includeInSymtab(const SymbolBody &B) {
-  if (!B.symbol()->IsUsedInRegularObj)
+  if (!B.isLocal() && !B.symbol()->IsUsedInRegularObj)
     return false;
 
   if (auto *D = dyn_cast<DefinedRegular<ELFT>>(&B)) {

Modified: lld/trunk/test/ELF/string-gc.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/string-gc.s?rev=268644&r1=268643&r2=268644&view=diff
==============================================================================
--- lld/trunk/test/ELF/string-gc.s (original)
+++ lld/trunk/test/ELF/string-gc.s Thu May  5 11:38:46 2016
@@ -13,7 +13,16 @@
 // CHECK-NEXT:     Section: Undefined (0x0)
 // CHECK-NEXT:   }
 // CHECK-NEXT:   Symbol {
-// CHECK-NEXT:     Name: s1 (8)
+// CHECK-NEXT:     Name: s3
+// CHECK-NEXT:     Value: 0x10125
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Local (0x0)
+// CHECK-NEXT:     Type: Object (0x1)
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: .rodata (0x1)
+// CHECK-NEXT:   }
+// CHECK-NEXT:   Symbol {
+// CHECK-NEXT:     Name: s1
 // CHECK-NEXT:     Value: 0x10120
 // CHECK-NEXT:     Size: 0
 // CHECK-NEXT:     Binding: Local (0x0)
@@ -24,7 +33,7 @@
 // CHECK-NEXT:     Section: .rodata (0x1)
 // CHECK-NEXT:   }
 // CHECK-NEXT:   Symbol {
-// CHECK-NEXT:     Name: _start (1)
+// CHECK-NEXT:     Name: _start
 // CHECK-NEXT:     Value: 0x11000
 // CHECK-NEXT:     Size: 0
 // CHECK-NEXT:     Binding: Global (0x1)
@@ -39,6 +48,7 @@
 .type _start, at function
 _start:
 movl $s1, %eax
+movl $s3, %eax
 
 .hidden s1
 .type s1, at object
@@ -52,3 +62,12 @@ s1:
 .globl s2
 s2:
 .asciz "efgh"
+
+.type s3, at object
+s3:
+.asciz "ijkl"
+
+.type s4, at object
+.globl s4
+s4:
+.asciz "mnop"