MIPS/GAS: Use non-zero frag offset directly in PIC branch relaxation

Use frag symbols with a non-zero offset directly in `fix_new_exp' calls
made in PIC branch relaxation.  There is no need here to make a helper
symbol to hold the result of a `symbol+offset' calculation requested as
only branches to local symbols are relaxed and in this case the LO16
part of the PIC address load sequence will have the offset accounted for
in calculation against the local GOT entry retrieved as the GOT16 high
part.  Consequently actual code produed is identical whether a helper
symbol is used or the original `symbol+offset' expression used directly.
Verify that this is indeed the case with GAS and LD tests.

	gas/
	* config/tc-mips.c (md_convert_frag): Don't make a helper
	expression symbol for `fix_new_exp' called with a non-zero
	offset.
	* testsuite/gas/mips/relax-offset.d: New test.
	* testsuite/gas/mips/mips1@relax-offset.d: New test.
	* testsuite/gas/mips/r3000@relax-offset.d: New test.
	* testsuite/gas/mips/r3900@relax-offset.d: New test.
	* testsuite/gas/mips/micromips@relax-offset.d: New test.
	* testsuite/gas/mips/relax-offset.l: New stderr output.
	* testsuite/gas/mips/relax-offset.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	ld/
	* testsuite/ld-mips-elf/relax-offset.dd: New test.
	* testsuite/ld-mips-elf/relax-offset.gd: New test.
	* testsuite/ld-mips-elf/relax-offset-umips.dd: New test.
	* testsuite/ld-mips-elf/relax-offset-umips.gd: New test.
	* testsuite/ld-mips-elf/relax-offset.ld: New test linker script.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
	(prune_warnings): New temporary procedure.

10 files changed, 137 insertions, 12 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 9989f31..7dad341 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,17 @@
+2017-06-30  Maciej W. Rozycki  <macro@imgtec.com>
+
+	* config/tc-mips.c (md_convert_frag): Don't make a helper
+	expression symbol for `fix_new_exp' called with a non-zero
+	offset.
+	* testsuite/gas/mips/relax-offset.d: New test.
+	* testsuite/gas/mips/mips1@relax-offset.d: New test.
+	* testsuite/gas/mips/r3000@relax-offset.d: New test.
+	* testsuite/gas/mips/r3900@relax-offset.d: New test.
+	* testsuite/gas/mips/micromips@relax-offset.d: New test.
+	* testsuite/gas/mips/relax-offset.l: New stderr output.
+	* testsuite/gas/mips/relax-offset.s: New test source.
+	* testsuite/gas/mips/mips.exp: Run the new tests.
+
 2017-06-30  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR gas/21683
diff --git a/gas/config/tc-mips.c b/gas/config/tc-mips.c
index 1d477a1..3682cd5 100644
--- a/gas/config/tc-mips.c
+++ b/gas/config/tc-mips.c
@@ -18289,12 +18289,6 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec, fragS *fragp)
 	      exp.X_add_symbol = fragp->fr_symbol;
 	      exp.X_add_number = fragp->fr_offset;
 
-	      if (fragp->fr_offset)
-		{
-		  exp.X_add_symbol = make_expr_symbol (&exp);
-		  exp.X_add_number = 0;
-		}
-
 	      fixp = fix_new_exp (fragp, buf - fragp->fr_literal, 4, &exp,
 				  FALSE, BFD_RELOC_MIPS_GOT16);
 	      fixp->fx_file = fragp->fr_file;
@@ -18548,12 +18542,6 @@ md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec, fragS *fragp)
 	  insn = HAVE_64BIT_ADDRESSES ? 0xdc1c0000 : 0xfc1c0000;
 	  insn |= at << MICROMIPSOP_SH_RT;
 
-	  if (exp.X_add_number)
-	    {
-	      exp.X_add_symbol = make_expr_symbol (&exp);
-	      exp.X_add_number = 0;
-	    }
-
 	  fixp = fix_new_exp (fragp, buf - fragp->fr_literal, 4, &exp, FALSE,
 			      BFD_RELOC_MICROMIPS_GOT16);
 	  fixp->fx_file = fragp->fr_file;
diff --git a/gas/testsuite/gas/mips/micromips@relax-offset.d b/gas/testsuite/gas/mips/micromips@relax-offset.d
new file mode 100644
index 0000000..95fbf11
--- /dev/null
+++ b/gas/testsuite/gas/mips/micromips@relax-offset.d
@@ -0,0 +1,26 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS PIC branch relaxation with offset
+#as: -32 -relax-branch
+#stderr: relax-offset.l
+#source: relax-offset.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 41bc 0000 	lui	gp,0x0
+[ 	]*[0-9a-f]+: R_MICROMIPS_HI16	_gp_disp
+[0-9a-f]+ <[^>]*> 339c 0000 	addiu	gp,gp,0
+[ 	]*[0-9a-f]+: R_MICROMIPS_LO16	_gp_disp
+[0-9a-f]+ <[^>]*> 033c e150 	addu	gp,gp,t9
+[0-9a-f]+ <[^>]*> 40a4 fffe 	bnezc	a0,0000000c <foo\+0xc>
+[ 	]*[0-9a-f]+: R_MICROMIPS_PC16_S1	.*
+[0-9a-f]+ <[^>]*> fc3c 0002 	lw	at,2\(gp\)
+[ 	]*[0-9a-f]+: R_MICROMIPS_GOT16	\.text
+[0-9a-f]+ <[^>]*> 3021 0025 	addiu	at,at,37
+[ 	]*[0-9a-f]+: R_MICROMIPS_LO16	\.text
+[0-9a-f]+ <[^>]*> 45a1      	jrc	at
+[0-9a-f]+ <[^>]*> 45bf      	jrc	ra
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000 8b7c 	syscall
+[0-9a-f]+ <[^>]*> 45bf      	jrc	ra
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/mips.exp b/gas/testsuite/gas/mips/mips.exp
index 81dfd34..0ea9f61 100644
--- a/gas/testsuite/gas/mips/mips.exp
+++ b/gas/testsuite/gas/mips/mips.exp
@@ -1069,6 +1069,8 @@ if { [istarget mips*-*-vxworks*] } {
 
     run_dump_test_arches "relax"	[mips_arch_list_matching mips2 !mips32r6]
     run_dump_test_arches "relax-at"	[mips_arch_list_matching mips2 !mips32r6]
+    run_dump_test_arches "relax-offset"	[mips_arch_list_matching mips1 \
+					    !mips32r6]
     run_dump_test "relax-swap1-mips1"
     run_dump_test "relax-swap1-mips2"
     run_dump_test "relax-swap2"
diff --git a/gas/testsuite/gas/mips/mips1@relax-offset.d b/gas/testsuite/gas/mips/mips1@relax-offset.d
new file mode 100644
index 0000000..bd38410
--- /dev/null
+++ b/gas/testsuite/gas/mips/mips1@relax-offset.d
@@ -0,0 +1,30 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS PIC branch relaxation with offset
+#as: -32 -relax-branch
+#stderr: relax-offset.l
+#source: relax-offset.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 3c1c0000 	lui	gp,0x0
+[ 	]*[0-9a-f]+: R_MIPS_HI16	_gp_disp
+[0-9a-f]+ <[^>]*> 279c0000 	addiu	gp,gp,0
+[ 	]*[0-9a-f]+: R_MIPS_LO16	_gp_disp
+[0-9a-f]+ <[^>]*> 0399e021 	addu	gp,gp,t9
+[0-9a-f]+ <[^>]*> 14800005 	bnez	a0,00000024 <foo\+0x24>
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8f810002 	lw	at,2\(gp\)
+[ 	]*[0-9a-f]+: R_MIPS_GOT16	\.text
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 24210034 	addiu	at,at,52
+[ 	]*[0-9a-f]+: R_MIPS_LO16	\.text
+[0-9a-f]+ <[^>]*> 00200008 	jr	at
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000000c 	syscall
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/r3000@relax-offset.d b/gas/testsuite/gas/mips/r3000@relax-offset.d
new file mode 100644
index 0000000..d726d32
--- /dev/null
+++ b/gas/testsuite/gas/mips/r3000@relax-offset.d
@@ -0,0 +1,6 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS PIC branch relaxation with offset
+#as: -32 -relax-branch
+#stderr: relax-offset.l
+#source: relax-offset.s
+#dump: mips1@relax-offset.d
diff --git a/gas/testsuite/gas/mips/r3900@relax-offset.d b/gas/testsuite/gas/mips/r3900@relax-offset.d
new file mode 100644
index 0000000..d726d32
--- /dev/null
+++ b/gas/testsuite/gas/mips/r3900@relax-offset.d
@@ -0,0 +1,6 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS PIC branch relaxation with offset
+#as: -32 -relax-branch
+#stderr: relax-offset.l
+#source: relax-offset.s
+#dump: mips1@relax-offset.d
diff --git a/gas/testsuite/gas/mips/relax-offset.d b/gas/testsuite/gas/mips/relax-offset.d
new file mode 100644
index 0000000..e7f36e2
--- /dev/null
+++ b/gas/testsuite/gas/mips/relax-offset.d
@@ -0,0 +1,28 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS PIC branch relaxation with offset
+#as: -32 -relax-branch
+#stderr: relax-offset.l
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 3c1c0000 	lui	gp,0x0
+[ 	]*[0-9a-f]+: R_MIPS_HI16	_gp_disp
+[0-9a-f]+ <[^>]*> 279c0000 	addiu	gp,gp,0
+[ 	]*[0-9a-f]+: R_MIPS_LO16	_gp_disp
+[0-9a-f]+ <[^>]*> 0399e021 	addu	gp,gp,t9
+[0-9a-f]+ <[^>]*> 14800004 	bnez	a0,00000020 <foo\+0x20>
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8f810002 	lw	at,2\(gp\)
+[ 	]*[0-9a-f]+: R_MIPS_GOT16	\.text
+[0-9a-f]+ <[^>]*> 24210034 	addiu	at,at,52
+[ 	]*[0-9a-f]+: R_MIPS_LO16	\.text
+[0-9a-f]+ <[^>]*> 00200008 	jr	at
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 0000000c 	syscall
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
diff --git a/gas/testsuite/gas/mips/relax-offset.l b/gas/testsuite/gas/mips/relax-offset.l
new file mode 100644
index 0000000..570a783
--- /dev/null
+++ b/gas/testsuite/gas/mips/relax-offset.l
@@ -0,0 +1,2 @@
+.*: Assembler messages:
+.*:10: Warning: relaxed out-of-range branch into a jump
diff --git a/gas/testsuite/gas/mips/relax-offset.s b/gas/testsuite/gas/mips/relax-offset.s
new file mode 100644
index 0000000..6255322
--- /dev/null
+++ b/gas/testsuite/gas/mips/relax-offset.s
@@ -0,0 +1,23 @@
+	.abicalls
+
+	.align	4, 0
+	.globl	foo
+	.ent	foo
+foo:
+	.set	noreorder
+	.cpload	$25
+	.set	reorder
+	beq	$4, $0, bar + 4
+	jr	$31
+
+	.space	131072
+
+	.align	4, 0
+bar:
+	syscall
+	jr	$31
+	.end	foo
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.space	16
+	.align	4, 0