Fix BLX(1) for Thumb

[deliverable/binutils-gdb.git] / bfd / coff-arm.c

diff --git a/bfd/coff-arm.c b/bfd/coff-arm.c
index 3431567e44ad7e2cf8ce340c1ff9caffdeda848c..ad4813f808bb7546d1a42b9f30f6cc034cd96fd7 100644 (file)
--- a/bfd/coff-arm.c
+++ b/bfd/coff-arm.c
@@ -1588,18 +1588,18 @@ coff_arm_relocate_section (output_bfd, info, input_bfd, input_section,
 
              BFD_ASSERT (size == 4);
 
-              /* howto->pc_relative should be TRUE for type 14 BRANCH23 */
+              /* howto->pc_relative should be TRUE for type 14 BRANCH23.  */
               relocation -= (input_section->output_section->vma
                              + input_section->output_offset);
 
-              /* howto->pcrel_offset should be TRUE for type 14 BRANCH23 */
+              /* howto->pcrel_offset should be TRUE for type 14 BRANCH23.  */
               relocation -= address;
 
              /* No need to negate the relocation with BRANCH23.  */
              /* howto->complain_on_overflow == complain_overflow_signed for BRANCH23.  */
              /* howto->rightshift == 1 */
-             /* Drop unwanted bits from the value we are relocating to.  */
 
+             /* Drop unwanted bits from the value we are relocating to.  */
              check = relocation >> howto->rightshift;
 
              /* If this is a signed value, the rightshift just dropped
@@ -1613,13 +1613,9 @@ coff_arm_relocate_section (output_bfd, info, input_bfd, input_section,
 
              /* Get the value from the object file.  */
              if (bfd_big_endian (input_bfd))
-               {
-                 add = (((x) & 0x07ff0000) >> 4) | (((x) & 0x7ff) << 1);
-               }
+               add = (((x) & 0x07ff0000) >> 4) | (((x) & 0x7ff) << 1);
              else
-               {
-                 add = ((((x) & 0x7ff) << 12) | (((x) & 0x07ff0000) >> 15));
-               }
+               add = ((((x) & 0x7ff) << 12) | (((x) & 0x07ff0000) >> 15));
 
              /* Get the value from the object file with an appropriate sign.
                 The expression involving howto->src_mask isolates the upper
@@ -1629,18 +1625,16 @@ coff_arm_relocate_section (output_bfd, info, input_bfd, input_section,
                 can not get the upper bit, but that does not matter since
                 signed_add needs no adjustment to become negative in that
                 case.  */
-
              signed_add = add;
 
              if ((add & (((~ src_mask) >> 1) & src_mask)) != 0)
                signed_add -= (((~ src_mask) >> 1) & src_mask) << 1;
 
+             /* howto->bitpos == 0 */
              /* Add the value from the object file, shifted so that it is a
                 straight number.  */
-             /* howto->bitpos == 0 */
-
              signed_check += signed_add;
-             relocation += signed_add;
+             relocation   += signed_add;
 
              BFD_ASSERT (howto->complain_on_overflow == complain_overflow_signed);
 
@@ -1649,21 +1643,26 @@ coff_arm_relocate_section (output_bfd, info, input_bfd, input_section,
                  || signed_check < reloc_signed_min)
                overflow = true;
 
-             /* Put RELOCATION into the correct bits:  */
-
+             /* For the BLX(1) instruction remove bit 0 of the adjusted offset.
+                Bit 0 can only be set if the upper insn is at a half-word boundary,
+                since the destination address, an ARM instruction, must always be
+                on a word boundary.  The semantics of the BLX (1) instruction,
+                however, are that bit 0 in the offset must always be 0, and the
+                corresponding bit 1 in the target address will be set from bit
+                1 of the source address.  */
+             if ((x & 0x18000000) == 0x08000000)
+               relocation &= ~0x2;
+
+             /* Put the relocation into the correct bits.  */
              if (bfd_big_endian (input_bfd))
-               {
-                 relocation = (((relocation & 0xffe) >> 1)  | ((relocation << 4) & 0x07ff0000));
-               }
+               relocation = (((relocation & 0xffe) >> 1)  | ((relocation << 4) & 0x07ff0000));
              else
-               {
-                 relocation = (((relocation & 0xffe) << 15) | ((relocation >> 12) & 0x7ff));
-               }
+               relocation = (((relocation & 0xffe) << 15) | ((relocation >> 12) & 0x7ff));
 
-             /* Add RELOCATION to the correct bits of X:  */
+             /* Add the relocation to the correct bits of X.  */
              x = ((x & ~howto->dst_mask) | relocation);
 
-             /* Put the relocated value back in the object file:  */
+             /* Put the relocated value back in the object file.  */
              bfd_put_32 (input_bfd, x, location);
 
              rstat = overflow ? bfd_reloc_overflow : bfd_reloc_ok;