MIPS16: Add R_MIPS16_PC16_S1 branch relocation support

For R_MIPS16_PC16_S1 the calculation is `(sign_extend(A) + S - P) >> 1'
and the usual MIPS16 bit shuffling applies to relocated field handling,
as per the encoding of the branch target in the extended form of the
MIPS16 B, BEQZ, BNEZ, BTEQZ and BTNEZ instructions.

	include/
	* elf/mips.h (R_MIPS16_PC16_S1): New relocation.

	bfd/
	* elf32-mips.c (elf_mips16_howto_table_rel): Add
	R_MIPS16_PC16_S1.
	(mips16_reloc_map): Likewise.
	* elf64-mips.c (mips16_elf64_howto_table_rel): Likewise.
	(mips16_elf64_howto_table_rela): Likewise.
	(mips16_reloc_map): Likewise.
	* elfn32-mips.c (elf_mips16_howto_table_rel): Likewise.
	(elf_mips16_howto_table_rela): Likewise.
	(mips16_reloc_map): Likewise.
	* elfxx-mips.c (mips16_branch_reloc_p): New function.
	(mips16_reloc_p): Handle R_MIPS16_PC16_S1.
	(b_reloc_p): Likewise.
	(mips_elf_calculate_relocation): Likewise.
	(_bfd_mips_elf_check_relocs): Likewise.
	* reloc.c (BFD_RELOC_MIPS16_16_PCREL_S1): New relocation.
	* bfd-in2.h: Regenerate.
	* libbfd.h: Regenerate.

	gas/
	* config/tc-mips.c (mips16_reloc_p): Handle
	BFD_RELOC_MIPS16_16_PCREL_S1.
	(b_reloc_p): Likewise.
	(limited_pcrel_reloc_p): Likewise.
	(md_pcrel_from): Likewise.
	(md_apply_fix): Likewise.
	(tc_gen_reloc): Likewise.
	(md_convert_frag): Likewise.
	(mips_fix_adjustable): Update comment.
	* testsuite/gas/mips/mips16-branch-reloc-2.d: Remove error
	output, add dump patterns.
	* testsuite/gas/mips/mips16-branch-reloc-3.d: Remove error
	output, add dump patterns.
	* testsuite/gas/mips/mips16-branch-addend-2.d: Remove error
	output, add dump patterns.
	* testsuite/gas/mips/mips16-branch-addend-3.d: Remove error
	output, add dump patterns.
	* testsuite/gas/mips/mips16-branch-absolute.d: Remove error
	output, add dump patterns.
	* testsuite/gas/mips/mips16-branch-reloc-2.l: Remove file.
	* testsuite/gas/mips/mips16-branch-reloc-3.l: Remove file.
	* testsuite/gas/mips/mips16-branch-addend-2.l: Remove file.
	* testsuite/gas/mips/mips16-branch-addend-3.l: Remove file.
	* testsuite/gas/mips/mips16-branch-absolute.l: Remove file.
	* testsuite/gas/mips/mips16-branch-addend-2.s: Add padding.
	* testsuite/gas/mips/branch-weak.s: Adjust alignment, avoid
	implicit instruction padding, avoid MIPS16 JR->JRC conversion.
	* testsuite/gas/mips/branch-weak-6.d: New test.
	* testsuite/gas/mips/branch-weak-7.d: New test.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* testsuite/ld-mips-elf/mips16-branch-2.d: New test.
	* testsuite/ld-mips-elf/mips16-branch-3.d: New test.
	* testsuite/ld-mips-elf/mips16-branch-addend-2.d: New test.
	* testsuite/ld-mips-elf/mips16-branch-addend-3.d: New test.
	* testsuite/ld-mips-elf/mips16-branch.s: New test source.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.

8 files changed, 142 insertions, 6 deletions

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index bf95751..e6ed960 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,23 @@
+2016-06-28  Maciej W. Rozycki  <macro@imgtec.com>
+
+	* elf32-mips.c (elf_mips16_howto_table_rel): Add
+	R_MIPS16_PC16_S1.
+	(mips16_reloc_map): Likewise.
+	* elf64-mips.c (mips16_elf64_howto_table_rel): Likewise.
+	(mips16_elf64_howto_table_rela): Likewise.
+	(mips16_reloc_map): Likewise.
+	* elfn32-mips.c (elf_mips16_howto_table_rel): Likewise.
+	(elf_mips16_howto_table_rela): Likewise.
+	(mips16_reloc_map): Likewise.
+	* elfxx-mips.c (mips16_branch_reloc_p): New function.
+	(mips16_reloc_p): Handle R_MIPS16_PC16_S1.
+	(b_reloc_p): Likewise.
+	(mips_elf_calculate_relocation): Likewise.
+	(_bfd_mips_elf_check_relocs): Likewise.
+	* reloc.c (BFD_RELOC_MIPS16_16_PCREL_S1): New relocation.
+	* bfd-in2.h: Regenerate.
+	* libbfd.h: Regenerate.
+
 2016-06-27  Alan Modra  <amodra@gmail.com>
 
 	PR ld/19264
diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h
index ebed966..30513c4 100644
--- a/bfd/bfd-in2.h
+++ b/bfd/bfd-in2.h
@@ -2998,6 +2998,9 @@ to compensate for the borrow when the low bits are added.  */
   BFD_RELOC_MICROMIPS_10_PCREL_S1,
   BFD_RELOC_MICROMIPS_16_PCREL_S1,
 
+/* MIPS16 PC-relative relocation.  */
+  BFD_RELOC_MIPS16_16_PCREL_S1,
+
 /* MIPS PC-relative relocations.  */
   BFD_RELOC_MIPS_21_PCREL_S2,
   BFD_RELOC_MIPS_26_PCREL_S2,
diff --git a/bfd/elf32-mips.c b/bfd/elf32-mips.c
index 5654fb6..029de27 100644
--- a/bfd/elf32-mips.c
+++ b/bfd/elf32-mips.c
@@ -1027,6 +1027,21 @@ static reloc_howto_type elf_mips16_howto_table_rel[] =
 	 0x0000ffff,		/* src_mask */
 	 0x0000ffff,		/* dst_mask */
 	 FALSE),		/* pcrel_offset */
+
+  /* MIPS16 16-bit PC-relative branch offset.  */
+  HOWTO (R_MIPS16_PC16_S1,	/* type */
+	 1,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 TRUE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 _bfd_mips_elf_generic_reloc, /* special_function */
+	 "R_MIPS16_PC16_S1",	/* name */
+	 TRUE,			/* partial_inplace */
+	 0x0000ffff,		/* src_mask */
+	 0x0000ffff,		/* dst_mask */
+	 TRUE),			/* pcrel_offset */
 };
 
 static reloc_howto_type elf_micromips_howto_table_rel[] =
@@ -2023,7 +2038,8 @@ static const struct elf_reloc_map mips16_reloc_map[] =
     R_MIPS16_TLS_DTPREL_LO16 - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_GOTTPREL, R_MIPS16_TLS_GOTTPREL - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_TPREL_HI16, R_MIPS16_TLS_TPREL_HI16 - R_MIPS16_min },
-  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min }
+  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min },
+  { BFD_RELOC_MIPS16_16_PCREL_S1, R_MIPS16_PC16_S1 - R_MIPS16_min }
 };
 
 static const struct elf_reloc_map micromips_reloc_map[] =
diff --git a/bfd/elf64-mips.c b/bfd/elf64-mips.c
index 34144f0..f04c4b5 100644
--- a/bfd/elf64-mips.c
+++ b/bfd/elf64-mips.c
@@ -1881,6 +1881,21 @@ static reloc_howto_type mips16_elf64_howto_table_rel[] =
 	 0x0000ffff,		/* src_mask */
 	 0x0000ffff,		/* dst_mask */
 	 FALSE),		/* pcrel_offset */
+
+  /* MIPS16 16-bit PC-relative branch offset.  */
+  HOWTO (R_MIPS16_PC16_S1,	/* type */
+	 1,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 TRUE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 _bfd_mips_elf_generic_reloc, /* special_function */
+	 "R_MIPS16_PC16_S1",	/* name */
+	 TRUE,			/* partial_inplace */
+	 0x0000ffff,		/* src_mask */
+	 0x0000ffff,		/* dst_mask */
+	 TRUE),			/* pcrel_offset */
 };
 
 static reloc_howto_type mips16_elf64_howto_table_rela[] =
@@ -2082,6 +2097,21 @@ static reloc_howto_type mips16_elf64_howto_table_rela[] =
 	 0,			/* src_mask */
 	 0x0000ffff,		/* dst_mask */
 	 FALSE),		/* pcrel_offset */
+
+  /* MIPS16 16-bit PC-relative branch offset.  */
+  HOWTO (R_MIPS16_PC16_S1,	/* type */
+	 1,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 TRUE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 _bfd_mips_elf_generic_reloc, /* special_function */
+	 "R_MIPS16_PC16_S1",	/* name */
+	 FALSE,			/* partial_inplace */
+	 0,			/* src_mask */
+	 0x0000ffff,		/* dst_mask */
+	 TRUE),			/* pcrel_offset */
 };
 
 static reloc_howto_type micromips_elf64_howto_table_rel[] =
@@ -3415,7 +3445,8 @@ static const struct elf_reloc_map mips16_reloc_map[] =
     R_MIPS16_TLS_DTPREL_LO16 - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_GOTTPREL, R_MIPS16_TLS_GOTTPREL - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_TPREL_HI16, R_MIPS16_TLS_TPREL_HI16 - R_MIPS16_min },
-  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min }
+  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min },
+  { BFD_RELOC_MIPS16_16_PCREL_S1, R_MIPS16_PC16_S1 - R_MIPS16_min }
 };
 
 static const struct elf_reloc_map micromips_reloc_map[] =
diff --git a/bfd/elfn32-mips.c b/bfd/elfn32-mips.c
index c955877..734ebf6 100644
--- a/bfd/elfn32-mips.c
+++ b/bfd/elfn32-mips.c
@@ -1847,6 +1847,21 @@ static reloc_howto_type elf_mips16_howto_table_rel[] =
 	 0x0000ffff,		/* src_mask */
 	 0x0000ffff,		/* dst_mask */
 	 FALSE),		/* pcrel_offset */
+
+  /* MIPS16 16-bit PC-relative branch offset.  */
+  HOWTO (R_MIPS16_PC16_S1,	/* type */
+	 1,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 TRUE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 _bfd_mips_elf_generic_reloc, /* special_function */
+	 "R_MIPS16_PC16_S1",	/* name */
+	 TRUE,			/* partial_inplace */
+	 0x0000ffff,		/* src_mask */
+	 0x0000ffff,		/* dst_mask */
+	 TRUE),			/* pcrel_offset */
 };
 
 static reloc_howto_type elf_mips16_howto_table_rela[] =
@@ -2048,6 +2063,21 @@ static reloc_howto_type elf_mips16_howto_table_rela[] =
 	 0,			/* src_mask */
 	 0x0000ffff,		/* dst_mask */
 	 FALSE),		/* pcrel_offset */
+
+  /* MIPS16 16-bit PC-relative branch offset.  */
+  HOWTO (R_MIPS16_PC16_S1,	/* type */
+	 1,			/* rightshift */
+	 2,			/* size (0 = byte, 1 = short, 2 = long) */
+	 16,			/* bitsize */
+	 TRUE,			/* pc_relative */
+	 0,			/* bitpos */
+	 complain_overflow_signed, /* complain_on_overflow */
+	 _bfd_mips_elf_generic_reloc, /* special_function */
+	 "R_MIPS16_PC16_S1",	/* name */
+	 FALSE,			/* partial_inplace */
+	 0,			/* src_mask */
+	 0x0000ffff,		/* dst_mask */
+	 TRUE),			/* pcrel_offset */
 };
 
 static reloc_howto_type elf_micromips_howto_table_rel[] =
@@ -3231,7 +3261,8 @@ static const struct elf_reloc_map mips16_reloc_map[] =
     R_MIPS16_TLS_DTPREL_LO16 - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_GOTTPREL, R_MIPS16_TLS_GOTTPREL - R_MIPS16_min },
   { BFD_RELOC_MIPS16_TLS_TPREL_HI16, R_MIPS16_TLS_TPREL_HI16 - R_MIPS16_min },
-  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min }
+  { BFD_RELOC_MIPS16_TLS_TPREL_LO16, R_MIPS16_TLS_TPREL_LO16 - R_MIPS16_min },
+  { BFD_RELOC_MIPS16_16_PCREL_S1, R_MIPS16_PC16_S1 - R_MIPS16_min }
 };
 
 static const struct elf_reloc_map micromips_reloc_map[] =
diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index 3b7723e..e47276b 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -2090,7 +2090,11 @@ mips_elf_check_symbols (struct mips_elf_link_hash_entry *h, void *data)
 
    All we need to do here is shuffle the bits appropriately.
    As above, the two 16-bit halves must be swapped on a
-   little-endian system.  */
+   little-endian system.
+
+   Finally R_MIPS16_PC16_S1 corresponds to R_MIPS_PC16, however the
+   relocatable field is shifted by 1 rather than 2 and the same bit
+   shuffling is done as with the relocations above.  */
 
 static inline bfd_boolean
 mips16_reloc_p (int r_type)
@@ -2110,6 +2114,7 @@ mips16_reloc_p (int r_type)
     case R_MIPS16_TLS_GOTTPREL:
     case R_MIPS16_TLS_TPREL_HI16:
     case R_MIPS16_TLS_TPREL_LO16:
+    case R_MIPS16_PC16_S1:
       return TRUE;
 
     default:
@@ -2221,7 +2226,8 @@ b_reloc_p (int r_type)
   return (r_type == R_MIPS_PC26_S2
 	  || r_type == R_MIPS_PC21_S2
 	  || r_type == R_MIPS_PC16
-	  || r_type == R_MIPS_GNU_REL16_S2);
+	  || r_type == R_MIPS_GNU_REL16_S2
+	  || r_type == R_MIPS16_PC16_S1);
 }
 
 static inline bfd_boolean
@@ -2232,6 +2238,13 @@ aligned_pcrel_reloc_p (int r_type)
 }
 
 static inline bfd_boolean
+mips16_branch_reloc_p (int r_type)
+{
+  return (r_type == R_MIPS16_26
+	  || r_type == R_MIPS16_PC16_S1);
+}
+
+static inline bfd_boolean
 micromips_branch_reloc_p (int r_type)
 {
   return (r_type == R_MICROMIPS_26_S1
@@ -5562,7 +5575,7 @@ mips_elf_calculate_relocation (bfd *abfd, bfd *input_bfd,
     }
 
   /* Make sure MIPS16 and microMIPS are not used together.  */
-  if ((r_type == R_MIPS16_26 && target_is_micromips_code_p)
+  if ((mips16_branch_reloc_p (r_type) && target_is_micromips_code_p)
       || (micromips_branch_reloc_p (r_type) && target_is_16_bit_code_p))
    {
       (*_bfd_error_handler)
@@ -5994,6 +6007,21 @@ mips_elf_calculate_relocation (bfd *abfd, bfd *input_bfd,
       value &= howto->dst_mask;
       break;
 
+    case R_MIPS16_PC16_S1:
+      if (howto->partial_inplace)
+	addend = _bfd_mips_elf_sign_extend (addend, 17);
+
+      if ((was_local_p || h->root.root.type != bfd_link_hash_undefweak)
+	  && ((symbol + addend) & 1) == 0)
+	return bfd_reloc_outofrange;
+
+      value = symbol + addend - p;
+      if (was_local_p || h->root.root.type != bfd_link_hash_undefweak)
+	overflowed_p = mips_elf_overflow_p (value, 17);
+      value >>= howto->rightshift;
+      value &= howto->dst_mask;
+      break;
+
     case R_MIPS_PC21_S2:
       if (howto->partial_inplace)
 	addend = _bfd_mips_elf_sign_extend (addend, 23);
@@ -8346,6 +8374,7 @@ _bfd_mips_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	case R_MIPS_PC21_S2:
 	case R_MIPS_PC26_S2:
 	case R_MIPS16_26:
+	case R_MIPS16_PC16_S1:
 	case R_MICROMIPS_26_S1:
 	case R_MICROMIPS_PC7_S1:
 	case R_MICROMIPS_PC10_S1:
diff --git a/bfd/libbfd.h b/bfd/libbfd.h
index bf17f43..2b1777e 100644
--- a/bfd/libbfd.h
+++ b/bfd/libbfd.h
@@ -1156,6 +1156,7 @@ static const char *const bfd_reloc_code_real_names[] = { "@@uninitialized@@",
   "BFD_RELOC_MICROMIPS_7_PCREL_S1",
   "BFD_RELOC_MICROMIPS_10_PCREL_S1",
   "BFD_RELOC_MICROMIPS_16_PCREL_S1",
+  "BFD_RELOC_MIPS16_16_PCREL_S1",
   "BFD_RELOC_MIPS_21_PCREL_S2",
   "BFD_RELOC_MIPS_26_PCREL_S2",
   "BFD_RELOC_MIPS_18_PCREL_S3",
diff --git a/bfd/reloc.c b/bfd/reloc.c
index 443ad6f..e962e71 100644
--- a/bfd/reloc.c
+++ b/bfd/reloc.c
@@ -2305,6 +2305,11 @@ ENUMDOC
   microMIPS PC-relative relocations.
 
 ENUM
+  BFD_RELOC_MIPS16_16_PCREL_S1
+ENUMDOC
+  MIPS16 PC-relative relocation.
+
+ENUM
   BFD_RELOC_MIPS_21_PCREL_S2
 ENUMX
   BFD_RELOC_MIPS_26_PCREL_S2