[PATCH] D28841: ELF: Add support for relocation type R_X86_64_8.

[Peter Collingbourne via Phabricator via llvm-commits]

pcc created this revision.
Herald added subscribers: mehdi_amini, emaste.

Although this relocation type is not part of the x86-64 psABI, I intend to
use it internally as part of the ThinLTO implementation.


https://reviews.llvm.org/D28841

Files:
  lld/ELF/Target.cpp
  lld/test/ELF/Inputs/x86-64-reloc-8-error.s
  lld/test/ELF/Inputs/x86-64-reloc-8.s
  lld/test/ELF/x86-64-reloc-8.s


Index: lld/test/ELF/x86-64-reloc-8.s
===================================================================
--- /dev/null
+++ lld/test/ELF/x86-64-reloc-8.s
@@ -0,0 +1,14 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/x86-64-reloc-8.s -o %t1
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %S/Inputs/x86-64-reloc-8-error.s -o %t2
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
+// RUN: ld.lld -shared %t %t1 -o %t3
+
+// CHECK:      Contents of section .text:
+// CHECK-NEXT:   200000 42
+
+// RUN: not ld.lld -shared %t %t2 -o %t4 2>&1 | FileCheck --check-prefix=ERROR %s
+// ERROR: relocation R_X86_64_8 out of range
+
+.byte foo
Index: lld/test/ELF/Inputs/x86-64-reloc-8.s
===================================================================
--- /dev/null
+++ lld/test/ELF/Inputs/x86-64-reloc-8.s
@@ -0,0 +1,3 @@
+.globl foo
+.hidden foo
+foo = 0x42
Index: lld/test/ELF/Inputs/x86-64-reloc-8-error.s
===================================================================
--- /dev/null
+++ lld/test/ELF/Inputs/x86-64-reloc-8-error.s
@@ -0,0 +1,3 @@
+.globl foo
+.hidden foo
+foo = 256
Index: lld/ELF/Target.cpp
===================================================================
--- lld/ELF/Target.cpp
+++ lld/ELF/Target.cpp
@@ -631,6 +631,7 @@
 RelExpr X86_64TargetInfo<ELFT>::getRelExpr(uint32_t Type,
                                            const SymbolBody &S) const {
   switch (Type) {
+  case R_X86_64_8:
   case R_X86_64_32:
   case R_X86_64_32S:
   case R_X86_64_64:
@@ -857,6 +858,10 @@
 void X86_64TargetInfo<ELFT>::relocateOne(uint8_t *Loc, uint32_t Type,
                                          uint64_t Val) const {
   switch (Type) {
+  case R_X86_64_8:
+    checkUInt<8>(Loc, Val, Type);
+    *Loc = Val;
+    break;
   case R_X86_64_32:
     checkUInt<32>(Loc, Val, Type);
     write32le(Loc, Val);


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