[lld] r250334 - ELF2: Support --entry=<addr>.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Wed Oct 14 17:20:57 2015
New Revision: 250334

URL: http://llvm.org/viewvc/llvm-project?rev=250334&view=rev
Log:
ELF2: Support --entry=<addr>.

If an argument for --entry is a number, that's not a symbol name but
an absolute address. If that's the case, the address is directly set
to ELF header's e_entry.

Modified:
    lld/trunk/ELF/Config.h
    lld/trunk/ELF/Driver.cpp
    lld/trunk/ELF/Writer.cpp
    lld/trunk/test/elf2/entry.s

Modified: lld/trunk/ELF/Config.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Config.h?rev=250334&r1=250333&r2=250334&view=diff
==============================================================================
--- lld/trunk/ELF/Config.h (original)
+++ lld/trunk/ELF/Config.h Wed Oct 14 17:20:57 2015
@@ -58,6 +58,7 @@ struct Configuration {
   bool ZNow = false;
   ELFKind EKind = ELFNoneKind;
   uint16_t EMachine = llvm::ELF::EM_NONE;
+  uint64_t EntryAddr = -1;
 };
 
 extern Configuration *Config;

Modified: lld/trunk/ELF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Driver.cpp?rev=250334&r1=250333&r2=250334&view=diff
==============================================================================
--- lld/trunk/ELF/Driver.cpp (original)
+++ lld/trunk/ELF/Driver.cpp Wed Oct 14 17:20:57 2015
@@ -201,7 +201,11 @@ template <class ELFT> void LinkerDriver:
     // Add entry symbol.
     if (Config->Entry.empty())
       Config->Entry = (Config->EMachine == EM_MIPS) ? "__start" : "_start";
-    Config->EntrySym = Symtab.addUndefined(Config->Entry);
+
+    // Set either EntryAddr (if S is a number) or EntrySym (otherwise).
+    StringRef S = Config->Entry;
+    if (S.getAsInteger(0, Config->EntryAddr))
+      Config->EntrySym = Symtab.addUndefined(S);
 
     // In the assembly for 32 bit x86 the _GLOBAL_OFFSET_TABLE_ symbol
     // is magical and is used to produce a R_386_GOTPC relocation.

Modified: lld/trunk/ELF/Writer.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Writer.cpp?rev=250334&r1=250333&r2=250334&view=diff
==============================================================================
--- lld/trunk/ELF/Writer.cpp (original)
+++ lld/trunk/ELF/Writer.cpp Wed Oct 14 17:20:57 2015
@@ -648,9 +648,12 @@ template <class ELFT> void Writer<ELFT>:
   EHdr->e_type = Config->Shared ? ET_DYN : ET_EXEC;
   EHdr->e_machine = FirstObj.getEMachine();
   EHdr->e_version = EV_CURRENT;
-  if (Config->EntrySym)
+  if (Config->EntrySym) {
     if (auto *E = dyn_cast<ELFSymbolBody<ELFT>>(Config->EntrySym->repl()))
       EHdr->e_entry = getSymVA<ELFT>(*E);
+  } else if (Config->EntryAddr != uint64_t(-1)) {
+    EHdr->e_entry = Config->EntryAddr;
+  }
   EHdr->e_phoff = sizeof(Elf_Ehdr);
   EHdr->e_shoff = SectionHeaderOff;
   EHdr->e_ehsize = sizeof(Elf_Ehdr);

Modified: lld/trunk/test/elf2/entry.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/entry.s?rev=250334&r1=250333&r2=250334&view=diff
==============================================================================
--- lld/trunk/test/elf2/entry.s (original)
+++ lld/trunk/test/elf2/entry.s Wed Oct 14 17:20:57 2015
@@ -2,5 +2,16 @@
 # RUN: not ld.lld2 %t1 -o %t2
 # RUN: ld.lld2 %t1 -o %t2 -e _end
 
-.globl _end;
+# RUN: ld.lld2 %t1 -o %t2 -e 4096
+# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=DEC %s
+# RUN: ld.lld2 %t1 -o %t2 -e 0xcafe
+# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=HEX %s
+# RUN: ld.lld2 %t1 -o %t2 -e 0777
+# RUN: llvm-readobj -file-headers %t2 | FileCheck -check-prefix=OCT %s
+
+# DEC: Entry: 0x1000
+# HEX: Entry: 0xCAFE
+# OCT: Entry: 0x1FF
+
+.globl _end
 _end: