ELF: Handle R_ARM_V4BX correctly in PIC output files.

Previously we considered R_ARM_V4BX to be an absolute relocation,
which meant that we rejected it in read-only sections in PIC output
files. Instead, treat it as a hint relocation so that relocation
processing ignores it entirely.

Also fix a problem with the test case where it was never being run
because it has a .yaml extension and we don't run tests with that
extension.

Differential Revision: https://reviews.llvm.org/D55728

llvm-svn: 349216

lld/ELF/Arch/ARM.cpp

@@ -134,6 +134,12 @@ RelExpr ARM::getRelExpr(RelType Type, const Symbol &S,
     return R_NONE;
   case R_ARM_TLS_LE32:
     return R_TLS;
+  case R_ARM_V4BX:
+    // V4BX is just a marker to indicate there's a "bx rN" instruction at the
+    // given address. It can be used to implement a special linker mode which
+    // rewrites ARMv4T inputs to ARMv4. Since we support only ARMv4 input and
+    // not ARMv4 output, we can just ignore it.
+    return R_HINT;
   default:
     return R_ABS;
   }
@@ -514,12 +520,6 @@ void ARM::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
                   ((Val << 4) & 0x7000) |    // imm3
                   (Val & 0x00ff));           // imm8
     break;
-  case R_ARM_V4BX:
-    // V4BX is just a marker to indicate there's a "bx rN" instruction at the
-    // given address. It can be used to implement a special linker mode which
-    // rewrites ARMv4T inputs to ARMv4. Since we support only ARMv4 input and
-    // not ARMv4 output, we can just ignore it.
-    break;
   default:
     error(getErrorLocation(Loc) + "unrecognized reloc " + Twine(Type));
   }

lld/test/ELF/arm-v4bx.test

@@ -2,6 +2,8 @@
 # RUN: yaml2obj %s -o %t.o
 # RUN: ld.lld %t.o -o %t
 # RUN: llvm-readelf -sections %t | FileCheck %s
+# RUN: ld.lld -shared %t.o -o %t
+# RUN: llvm-readelf -sections %t | FileCheck %s
 
 # CHECK: .text