MIPS: Fix the encoding of immediates with microMIPS JALX

The microMIPS JALX instruction shares the R_MICROMIPS_26_S1 relocation
with microMIPS J/JAL/JALS instructions, however unlike the latters its
encoded immediate argument is unusually shifted left by 2 rather than 1
in calculating the value used for the operation requested.

We already handle this exception in `mips_elf_calculate_relocation' in
LD, in a scenario where JALX is produced as a result of relaxing JAL for
the purpose of making a cross-mode jump.  We also get it right in the
disassembler in `decode_micromips_operand'.

What we don't correctly do however is processing microMIPS JALX produced
by GAS from an assembly source, where a non-zero constant argument or a
symbol reference with a non-zero in-place addend has been used.  In this
case the same calculation is made as for microMIPS J/JAL/JALS, causing
the wrong encoding to be produced by GAS on making an object file, and
then again by LD in the final link.  The latter in particular causes the
calculation, where the addend fits in the relocatable field, to produce
different final addresses for the same source code depending on whether
REL or RELA relocations are used.

Correct these issues by special-casing microMIPS JALX in the places that
have been previously missed.

	bfd/
	* elfxx-mips.c (mips_elf_read_rel_addend): Adjust the addend for
	microMIPS JALX.

	gas/
	* config/tc-mips.c (append_insn): Correct the encoding of a
	constant argument for microMIPS JALX.
	(tc_gen_reloc): Correct the encoding of an in-place addend for
	microMIPS JALX.
	* testsuite/gas/mips/jalx-addend.d: New test.
	* testsuite/gas/mips/jalx-addend-n32.d: New test.
	* testsuite/gas/mips/jalx-addend-n64.d: New test.
	* testsuite/gas/mips/jalx-imm.d: New test.
	* testsuite/gas/mips/jalx-imm-n32.d: New test.
	* testsuite/gas/mips/jalx-imm-n64.d: New test.
	* testsuite/gas/mips/jalx-addend.s: New test source.
	* testsuite/gas/mips/jalx-imm.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* testsuite/ld-mips-elf/jalx-addend.d: New test.
	* testsuite/ld-mips-elf/jalx-addend-n32.d: New test.
	* testsuite/ld-mips-elf/jalx-addend-n64.d: New test.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.

4 files changed, 44 insertions, 0 deletions

diff --git a/ld/testsuite/ld-mips-elf/jalx-addend-n32.d b/ld/testsuite/ld-mips-elf/jalx-addend-n32.d
new file mode 100644
index 0000000..a364422
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/jalx-addend-n32.d
@@ -0,0 +1,6 @@
+#name: MIPS JAL/JALX addend calculation (n32)
+#source: ../../../gas/testsuite/gas/mips/jalx-addend.s
+#as: -EB -n32 -march=from-abi
+#ld: -EB -Ttext 0x1c000000 -e 0x1c000000
+#objdump: -dr --prefix-addresses --show-raw-insn
+#dump: jalx-addend.d
diff --git a/ld/testsuite/ld-mips-elf/jalx-addend-n64.d b/ld/testsuite/ld-mips-elf/jalx-addend-n64.d
new file mode 100644
index 0000000..b6884c5
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/jalx-addend-n64.d
@@ -0,0 +1,6 @@
+#name: MIPS JAL/JALX addend calculation (n64)
+#source: ../../../gas/testsuite/gas/mips/jalx-addend.s
+#as: -EB -64 -march=from-abi
+#ld: -EB -Ttext 0x1c000000 -e 0x1c000000
+#objdump: -dr --prefix-addresses --show-raw-insn
+#dump: jalx-addend.d
diff --git a/ld/testsuite/ld-mips-elf/jalx-addend.d b/ld/testsuite/ld-mips-elf/jalx-addend.d
new file mode 100644
index 0000000..39cf6f9
--- /dev/null
+++ b/ld/testsuite/ld-mips-elf/jalx-addend.d
@@ -0,0 +1,26 @@
+#name: MIPS JAL/JALX addend calculation
+#source: ../../../gas/testsuite/gas/mips/jalx-addend.s
+#as: -EB -32
+#ld: -EB -Ttext 0x1c000000 -e 0x1c000000
+#objdump: -dr --prefix-addresses --show-raw-insn
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> f400 0801 	jal	0*18001002 <.*>
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> f100 0409 	jalx	0*14001024 <.*>
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 001f 0f3c 	jr	ra
+[0-9a-f]+ <[^>]*> 0000 02d0 	not	zero,zero
+[0-9a-f]+ <[^>]*> 0000 0000 	nop
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 75000401 	jalx	0*14001004 <.*>
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 0d000409 	jal	0*14001024 <.*>
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+[0-9a-f]+ <[^>]*> 03e00009 	jalr	zero,ra
+[0-9a-f]+ <[^>]*> 00000027 	nor	zero,zero,zero
+	\.\.\.
diff --git a/ld/testsuite/ld-mips-elf/mips-elf.exp b/ld/testsuite/ld-mips-elf/mips-elf.exp
index 4467719..741f2e2 100644
--- a/ld/testsuite/ld-mips-elf/mips-elf.exp
+++ b/ld/testsuite/ld-mips-elf/mips-elf.exp
@@ -168,6 +168,12 @@ if { $linux_gnu } {
 	      "jalx-2"]]
 }
 
+run_dump_test "jalx-addend" [list [list ld $abi_ldflags(o32)]]
+if $has_newabi {
+    run_dump_test "jalx-addend-n32" [list [list ld $abi_ldflags(n32)]]
+    run_dump_test "jalx-addend-n64" [list [list ld $abi_ldflags(n64)]]
+}
+
 # Test multi-got link.  We only do this on GNU/Linux because it requires
 # the "traditional" emulations.
 if { $linux_gnu } {