[lld] r250584 - [ELF2] - Implemented R_X86_64_PLT32 relocation.

[George Rimar via llvm-commits]

Author: grimar
Date: Fri Oct 16 18:52:24 2015
New Revision: 250584

URL: http://llvm.org/viewvc/llvm-project?rev=250584&view=rev
Log:
[ELF2] - Implemented R_X86_64_PLT32 relocation.

There is sometimes no need to generate relocation via PLT. 
Example - when symbol is not undefined and we are not creating shared library. Then we can create relative relocation instead of referencing and creating PLT records.

Differential Revision: http://reviews.llvm.org/D13835

Modified:
    lld/trunk/ELF/Target.cpp
    lld/trunk/test/elf2/plt.s

Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=250584&r1=250583&r2=250584&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Fri Oct 16 18:52:24 2015
@@ -256,7 +256,7 @@ bool X86_64TargetInfo::relocNeedsPlt(uin
     // R_386_JMP_SLOT, etc).
     return S.isShared();
   case R_X86_64_PLT32:
-    return true;
+    return canBePreempted(&S, true);
   }
 }
 
@@ -297,6 +297,9 @@ void X86_64TargetInfo::relocateOne(uint8
     write32le(Loc, SA);
     break;
   }
+  case R_X86_64_PLT32:
+    write32le(Loc, SA - BaseAddr - Offset);
+    break;
   default:
     error("unrecognized reloc " + Twine(Type));
   }

Modified: lld/trunk/test/elf2/plt.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/elf2/plt.s?rev=250584&r1=250583&r2=250584&view=diff
==============================================================================
--- lld/trunk/test/elf2/plt.s (original)
+++ lld/trunk/test/elf2/plt.s Fri Oct 16 18:52:24 2015
@@ -2,8 +2,12 @@
 // RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t2.o
 // RUN: ld.lld2 -shared %t2.o -o %t2.so
 // RUN: ld.lld2 -shared %t.o %t2.so -o %t
+// RUN: ld.lld2 %t.o %t2.so -o %t3
 // RUN: llvm-readobj -s -r %t | FileCheck %s
 // RUN: llvm-objdump -d %t | FileCheck --check-prefix=DISASM %s
+// RUN: llvm-readobj -s -r %t3 | FileCheck --check-prefix=CHECK2 %s
+// RUN: llvm-objdump -d %t3 | FileCheck --check-prefix=DISASM2 %s
+
 // REQUIRES: x86
 
 // CHECK:      Name: .plt
@@ -27,20 +31,43 @@
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
+// CHECK2:      Name: .plt
+// CHECK2-NEXT: Type: SHT_PROGBITS
+// CHECK2-NEXT: Flags [
+// CHECK2-NEXT:   SHF_ALLOC
+// CHECK2-NEXT:   SHF_EXECINSTR
+// CHECK2-NEXT: ]
+// CHECK2-NEXT: Address: 0x11020
+// CHECK2-NEXT: Offset:
+// CHECK2-NEXT: Size: 16
+// CHECK2-NEXT: Link: 0
+// CHECK2-NEXT: Info: 0
+// CHECK2-NEXT: AddressAlignment: 16
+
+// CHECK2:      Relocations [
+// CHECK2-NEXT:   Section ({{.*}}) .rela.dyn {
+// CHECK2-NEXT:     0x120A0 R_X86_64_GLOB_DAT bar 0x0
+// CHECK2-NEXT:     0x120A8 R_X86_64_GLOB_DAT zed 0x0
+// CHECK2-NEXT:   }
+// CHECK2-NEXT: ]
+
 // Unfortunately FileCheck can't do math, so we have to check for explicit
 // values:
 
-// 0x11020 - (0x11000 + 1) - 4 = 27
-// 0x11020 - (0x11005 + 1) - 4 = 22
-// 0x11028 - (0x1100a + 1) - 4 = 25
+// 0x1020 - (0x1000 + 1) - 4 = 27
+// 0x1020 - (0x1005 + 1) - 4 = 22
+// 0x1028 - (0x100a + 1) - 4 = 25
+// 0x1030 - (0x100f + 1) - 4 = 28
 
 // DISASM:      _start:
 // DISASM-NEXT:   1000:  e9 {{.*}}       jmp  27
 // DISASM-NEXT:   1005:  e9 {{.*}}       jmp  22
 // DISASM-NEXT:   100a:  e9 {{.*}}       jmp  25
+// DISASM-NEXT:   100f:  e9 {{.*}}       jmp  28
 
-// 0x120A0 - 0x11026  = 4218
-// 0x120A8 - 0x1102e  = 4218
+// 0x20A0 - 0x1026  = 4218
+// 0x20A8 - 0x102e  = 4218
+// 0x20B0 - 0x1036  = 4218
 
 // DISASM:      Disassembly of section .plt:
 // DISASM-NEXT: .plt:
@@ -50,6 +77,30 @@
 // DISASM-NEXT:   1028:  ff 25 {{.*}}       jmpq *4218(%rip)
 // DISASM-NEXT:   102e:  90                 nop
 // DISASM-NEXT:   102f:  90                 nop
+// DISASM-NEXT:   1030:  ff 25 {{.*}}       jmpq *4218(%rip)
+// DISASM-NEXT:   1036:  90                 nop
+// DISASM-NEXT:   1037:  90                 nop
+
+// 0x11020 - (0x11000 + 1) - 4 = 27
+// 0x11020 - (0x11005 + 1) - 4 = 22
+// 0x11028 - (0x1100a + 1) - 4 = 25
+// 0x11000 - (0x1100f + 1) - 4 = -20
+
+// DISASM2:      _start:
+// DISASM2-NEXT:   11000:  e9 {{.*}}     jmp  27
+// DISASM2-NEXT:   11005:  e9 {{.*}}     jmp  22
+// DISASM2-NEXT:   1100a:  e9 {{.*}}     jmp  25
+// DISASM2-NEXT:   1100f:  e9 {{.*}}     jmp  -20
+
+// DISASM2:      Disassembly of section .plt:
+// DISASM2-NEXT: .plt:
+// DISASM2-NEXT:     11020:  ff 25 7a 10 00 00 jmpq *4218(%rip)
+// DISASM2-NEXT:     11026:  90                nop
+// DISASM2-NEXT:     11027:  90                nop
+// DISASM2-NEXT:     11028:  ff 25 7a 10 00 00 jmpq *4218(%rip)
+// DISASM2-NEXT:     1102e:  90                nop
+// DISASM2-NEXT:     1102f:  90                nop
+// DISASM2-NEXT-NOT: 110C0
 
 .global _start
 _start: