[lld] r293683 - Check R_386_{PC,}{8,16} for overflow.

[Rui Ueyama via llvm-commits]

Author: ruiu
Date: Tue Jan 31 14:28:32 2017
New Revision: 293683

URL: http://llvm.org/viewvc/llvm-project?rev=293683&view=rev
Log:
Check R_386_{PC,}{8,16} for overflow.

It is not clear what we should do when overflow occurs for these
relocations because the relocations are not an official part of
the i386 psABI. But checking for overflow is generally a good to do
and is consistent with other relocations such as R_X86_64_8.

Modified:
    lld/trunk/ELF/Target.cpp

Modified: lld/trunk/ELF/Target.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/Target.cpp?rev=293683&r1=293682&r2=293683&view=diff
==============================================================================
--- lld/trunk/ELF/Target.cpp (original)
+++ lld/trunk/ELF/Target.cpp Tue Jan 31 14:28:32 2017
@@ -512,17 +512,24 @@ uint64_t X86TargetInfo::getImplicitAdden
 
 void X86TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
                                 uint64_t Val) const {
-  checkInt<32>(Loc, Val, Type);
-
   // R_386_{PC,}{8,16} are not part of the i386 psABI, but they are
   // being used for some 16-bit programs such as boot loaders, so
   // we want to support them.
-  if (Type == R_386_8 || Type == R_386_PC8)
+  switch (Type) {
+  case R_386_8:
+  case R_386_PC8:
+    checkInt<8>(Loc, Val, Type);
     *Loc = Val;
-  else if (Type == R_386_16 || Type == R_386_PC16)
+    break;
+  case R_386_16:
+  case R_386_PC16:
+    checkInt<16>(Loc, Val, Type);
     write16le(Loc, Val);
-  else
+    break;
+  default:
+    checkInt<32>(Loc, Val, Type);
     write32le(Loc, Val);
+  }
 }
 
 void X86TargetInfo::relaxTlsGdToLe(uint8_t *Loc, uint32_t Type,