[PATCH] D29490: [ELF] - Use SignExtend when reading R_386_PC8 addend.

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 86970.
grimar added a comment.

- Addressed comments, simplified testcase.


https://reviews.llvm.org/D29490

Files:
  ELF/Target.cpp
  test/ELF/i386-pc8-addend.s


Index: test/ELF/i386-pc8-addend.s
===================================================================
--- test/ELF/i386-pc8-addend.s
+++ test/ELF/i386-pc8-addend.s
@@ -0,0 +1,25 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=i386-pc-linux-gnu %S/Inputs/i386-pc8.s -o %t2.o
+# RUN: llvm-objdump -d %t1.o | FileCheck %s --check-prefix=OBJDISASM
+
+## Show that we have relocation with addend = 0xFF(-1),
+## we do sign extend for its value in the code.
+# OBJDISASM:      Disassembly of section .text:
+# OBJDISASM-NEXT: .text:
+# OBJDISASM-NEXT:  0: ff
+
+## Check that there is no link error and relocation applied correctly.
+# RUN: ld.lld %t1.o %t2.o -o %t.out
+# RUN: llvm-objdump -d %t.out | FileCheck %s --check-prefix=DISASM
+# RUN: llvm-readobj -symbols %t.out | FileCheck %s --check-prefix=SYM
+# DISASM:      Disassembly of section .text:
+# DISASM-NEXT: .text:
+# DISASM-NEXT:   11000: 03
+## 0x11004 - 0x11000 + addend = 0x3
+# SYM:     Symbol {
+# SYM:       Name: und
+# SYM-NEXT:  Value: 0x11004
+
+.code16
+.byte  und-.-1
Index: ELF/Target.cpp
===================================================================
--- ELF/Target.cpp
+++ ELF/Target.cpp
@@ -492,8 +492,9 @@
   default:
     return 0;
   case R_386_8:
-  case R_386_PC8:
     return *Buf;
+  case R_386_PC8:
+    return SignExtend64<8>(*Buf);
   case R_386_16:
   case R_386_PC16:
     return read16le(Buf);


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