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[committed] MIPS/GAS: Correct branch relaxation for weak symbols

From: "Maciej W. Rozycki" <macro at imgtec dot com>
To: <binutils at sourceware dot org>
Cc: Andrew Bennett <andrew dot bennett at imgtec dot com>
Date: Wed, 13 Apr 2016 13:41:47 +0100
Subject: [committed] MIPS/GAS: Correct branch relaxation for weak symbols
Authentication-results: sourceware.org; auth=none
Weak symbols can be preempted at link time so always choose the longer 
sequence in branch relaxation, according to the relaxation level chosen, 
so that any symbol finally used as the branch target is reachable.

2016-04-13  Maciej W. Rozycki  <macro@imgtec.com>
            Andrew Bennett  <andrew.bennett@imgtec.com>

	gas/
	* config/tc-mips.c (relaxed_branch_length): Use the long 
	sequence where the target is a weak symbol.
	(relaxed_micromips_32bit_branch_length): Likewise.
	(relaxed_micromips_16bit_branch_length): Likewise.
	* testsuite/gas/mips/branch-weak-1.d: New test.
	* testsuite/gas/mips/branch-weak-2.d: New test.
	* testsuite/gas/mips/branch-weak-3.d: New test.
	* testsuite/gas/mips/branch-weak-4.d: New test.
	* testsuite/gas/mips/branch-weak-5.d: New test.
	* testsuite/gas/mips/branch-weak.l: New stderr output.
	* testsuite/gas/mips/branch-weak.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.
---

 I have committed this change.

  Maciej

binutils-mips-gas-branch-relax-weak.diff
Index: binutils/gas/config/tc-mips.c
===================================================================
--- binutils.orig/gas/config/tc-mips.c	2016-04-08 20:45:32.316129627 +0100
+++ binutils/gas/config/tc-mips.c	2016-04-09 00:04:57.375976880 +0100
@@ -16796,6 +16796,7 @@ relaxed_branch_length (fragS *fragp, ase
 
   if (fragp
       && S_IS_DEFINED (fragp->fr_symbol)
+      && !S_IS_WEAK (fragp->fr_symbol)
       && sec == S_GET_SEGMENT (fragp->fr_symbol))
     {
       addressT addr;
@@ -16859,6 +16860,7 @@ relaxed_micromips_32bit_branch_length (f
 
   if (fragp
       && S_IS_DEFINED (fragp->fr_symbol)
+      && !S_IS_WEAK (fragp->fr_symbol)
       && sec == S_GET_SEGMENT (fragp->fr_symbol))
     {
       addressT addr;
@@ -16950,6 +16952,7 @@ relaxed_micromips_16bit_branch_length (f
 
   if (fragp
       && S_IS_DEFINED (fragp->fr_symbol)
+      && !S_IS_WEAK (fragp->fr_symbol)
       && sec == S_GET_SEGMENT (fragp->fr_symbol))
     {
       addressT addr;
Index: binutils/gas/testsuite/gas/mips/branch-weak-1.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak-1.d	2016-04-09 00:04:57.473685573 +0100
@@ -0,0 +1,15 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS branch to a weak symbol
+#as: -32 --defsym align=12
+#source: branch-weak.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 1000ffff 	b	00000000 <foo>
+[ 	]*[0-9a-f]+: R_MIPS_PC16	bar
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
Index: binutils/gas/testsuite/gas/mips/branch-weak-2.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak-2.d	2016-04-09 00:04:57.520445434 +0100
@@ -0,0 +1,15 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: microMIPS branch to a weak symbol
+#as: -32 -mmicromips --defsym align=12
+#source: branch-weak.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 9400 fffe 	b	00000000 <foo>
+[ 	]*[0-9a-f]+: R_MICROMIPS_PC16_S1	bar
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 459f      	jr	ra
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
Index: binutils/gas/testsuite/gas/mips/branch-weak-3.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak-3.d	2016-04-09 00:04:57.529841492 +0100
@@ -0,0 +1,16 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS relaxed branch to a weak symbol
+#as: -32 --relax-branch --defsym align=12
+#source: branch-weak.s
+#stderr: branch-weak.l
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 08000000 	j	00000000 <foo>
+[ 	]*[0-9a-f]+: R_MIPS_26	bar
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 03e00008 	jr	ra
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
Index: binutils/gas/testsuite/gas/mips/branch-weak-4.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak-4.d	2016-04-09 00:04:57.553233691 +0100
@@ -0,0 +1,16 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: microMIPS relaxed branch to a weak symbol
+#as: -32 -mmicromips --relax-branch --defsym align=12
+#source: branch-weak.s
+#stderr: branch-weak.l
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> d400 0000 	j	00000000 <foo>
+[ 	]*[0-9a-f]+: R_MICROMIPS_26_S1	bar
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 459f      	jr	ra
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
Index: binutils/gas/testsuite/gas/mips/branch-weak-5.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak-5.d	2016-04-09 00:04:57.566606951 +0100
@@ -0,0 +1,15 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: microMIPS short branch to a weak symbol
+#as: -32 -mmicromips --defsym align=4
+#source: branch-weak.s
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 9400 fffe 	b	00000000 <foo>
+[ 	]*[0-9a-f]+: R_MICROMIPS_PC16_S1	bar
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
+[0-9a-f]+ <[^>]*> 459f      	jr	ra
+[0-9a-f]+ <[^>]*> 0c00      	nop
+	\.\.\.
Index: binutils/gas/testsuite/gas/mips/branch-weak.l
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak.l	2016-04-09 00:04:57.665927349 +0100
@@ -0,0 +1,2 @@
+.*: Assembler messages:
+.*:6: Warning: relaxed out-of-range branch into a jump
Index: binutils/gas/testsuite/gas/mips/branch-weak.s
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils/gas/testsuite/gas/mips/branch-weak.s	2016-04-09 00:04:57.709838646 +0100
@@ -0,0 +1,19 @@
+	.text
+	.align	4, 0
+	.globl	foo
+	.ent	foo
+foo:
+	b	bar
+	.end	foo
+
+	.align	align, 0
+	.globl	bar
+	.weak	bar
+	.ent	bar
+bar:
+	jr	$ra
+	.end	bar
+
+# Force some (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align  4, 0
+	.space  16
Index: binutils/gas/testsuite/gas/mips/mips.exp
===================================================================
--- binutils.orig/gas/testsuite/gas/mips/mips.exp	2016-04-08 20:46:10.480257638 +0100
+++ binutils/gas/testsuite/gas/mips/mips.exp	2016-04-09 00:04:57.722222289 +0100
@@ -578,6 +578,11 @@ if { [istarget mips*-*-vxworks*] } {
     run_dump_test "branch-extern-2"
     run_dump_test "branch-extern-3"
     run_dump_test "branch-extern-4"
+    run_dump_test "branch-weak-1"
+    run_dump_test "branch-weak-2"
+    run_dump_test "branch-weak-3"
+    run_dump_test "branch-weak-4"
+    run_dump_test "branch-weak-5"
 
     run_dump_test "compact-eh-eb-1"
     run_dump_test "compact-eh-eb-2"
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