commit 2b675074feda2e8d643909c5fa9ab2bcb67c8581
author Rui Ueyama <ruiu@google.com> Wed Oct 14 22:20:57 2015 +0000
committer Rui Ueyama <ruiu@google.com> Wed Oct 14 22:20:57 2015 +0000
tree c439f573e4bbf0caf20c0366bbb61197883d653f
parent f9e0b253ad605a429526b54ffdfcf121deaf082c

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.

llvm-svn: 250334

lld/ELF/Config.h

diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index bac8382..b28877e 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -58,6 +58,7 @@
   bool ZNow = false;
   ELFKind EKind = ELFNoneKind;
   uint16_t EMachine = llvm::ELF::EM_NONE;
+  uint64_t EntryAddr = -1;
 };
 
 extern Configuration *Config;

lld/ELF/Driver.cpp

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 53be66c..2d7d75c 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -201,7 +201,11 @@
     // 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.

lld/ELF/Writer.cpp

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 4307b48..4861dc1 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -648,9 +648,12 @@
   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);

lld/test/elf2/entry.s

diff --git a/lld/test/elf2/entry.s b/lld/test/elf2/entry.s
index b933560..5f85f9e 100644
--- a/lld/test/elf2/entry.s
+++ b/lld/test/elf2/entry.s
@@ -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: