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[PATCH 4/4] MIPS/GAS: Actual o32 SVR4 PIC JAL macro delay slot fix

From: "Maciej W. Rozycki" <macro at codesourcery dot com>
To: binutils at sourceware dot org
Cc: Richard Sandiford <rdsandiford at googlemail dot com>, Catherine Moore <clm at codesourcery dot com>, gnu-mips-sgxx at codesourcery dot com
Date: Tue, 20 Jul 2010 12:43:53 +0100 (BST)
Subject: [PATCH 4/4] MIPS/GAS: Actual o32 SVR4 PIC JAL macro delay slot fix

Hi,

 This is a change that fixes a problem when code like this:

	.set	noreorder
	jal	$25
	.set	reorder

is assembled to a piece like this with the o32 ABI:

	jalr	$25
	 lw	$gp, 0($sp)

rather than the expected:

	jalr	$25
	 nop
	lw	$gp, 0($sp)

making the reload of the GOT pointer to happen before the function call 
rather than afterwards.  Since it's within a macro rather than between 
macros/instructions, noreorder shouldn't place the LW into the delay slot 
breaking the macro irrecoverably.

 A similar JAL macro expanded with the use of a symbol rather than a 
register:

	.set	noreorder
	jal	foo
	.set	reorder

works correctly already by scheduling an extra NOP between the JALR and 
the LW in the noreorder mode.

 Both macros are covered by the included test case, trivially derived from 
jal-svr4pic.
	
2010-07-20  Maciej W. Rozycki  <macro@codesourcery.com>

	gas/
	* config/tc-mips.c (macro)[M_JAL_1, M_JAL_2]: Handle the JALR 
	delay slot in the noreorder mode with the o32 ABI.

	gas/testsuite/
	* gas/mips/jal-svr4pic-noreorder.d: New test case.
	* gas/mips/mips1@jal-svr4pic-noreorder.d: New test 
	subarchitecture.
	* gas/mips/r3000@jal-svr4pic-noreorder.d: Likewise.
	* gas/mips/jal-svr4pic-noreorder.s: Source for the new test
	case.
	* gas/mips/mips.exp: Run the new test case.

 OK to commit?

  Maciej

binutils-jal-svr4pic-noreorder.diff
Index: binutils-fsf-trunk-quilt/gas/config/tc-mips.c
===================================================================
--- binutils-fsf-trunk-quilt.orig/gas/config/tc-mips.c	2010-07-20 00:35:37.000000000 +0100
+++ binutils-fsf-trunk-quilt/gas/config/tc-mips.c	2010-07-20 00:48:16.000000000 +0100
@@ -6219,6 +6219,8 @@
 		      /* Quiet this warning.  */
 		      mips_cprestore_valid = 1;
 		    }
+		  if (mips_opts.noreorder)
+		    macro_build (NULL, "nop", "");
 		  expr1.X_add_number = mips_cprestore_offset;
   		  macro_build_ldst_constoffset (&expr1, ADDRESS_LOAD_INSN,
 						mips_gp_register,
Index: binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/jal-svr4pic-noreorder.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/jal-svr4pic-noreorder.d	2010-07-20 00:48:16.000000000 +0100
@@ -0,0 +1,45 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS jal-svr4pic noreorder
+#as: -32 -KPIC
+#source: jal-svr4pic-noreorder.s
+
+# Test the jal macro with -KPIC and `.set noreorder'.
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 3c1c0000 	lui	gp,0x0
+[ 	]*0: R_MIPS_HI16	_gp_disp
+[0-9a-f]+ <[^>]*> 279c0000 	addiu	gp,gp,0
+[ 	]*4: R_MIPS_LO16	_gp_disp
+[0-9a-f]+ <[^>]*> 0399e021 	addu	gp,gp,t9
+[0-9a-f]+ <[^>]*> afbc0000 	sw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 03202009 	jalr	a0,t9
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*28: R_MIPS_GOT16	.text
+[0-9a-f]+ <[^>]*> 27390000 	addiu	t9,t9,0
+[ 	]*2c: R_MIPS_LO16	.text
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*30: R_MIPS_JALR	text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*3c: R_MIPS_CALL16	weak_text_label
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*40: R_MIPS_JALR	weak_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*4c: R_MIPS_CALL16	external_text_label
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*50: R_MIPS_JALR	external_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 1000ffe8 	b	0+0000 <text_label>
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
Index: binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/jal-svr4pic-noreorder.s
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/jal-svr4pic-noreorder.s	2010-07-20 02:37:29.000000000 +0100
@@ -0,0 +1,27 @@
+# Source file used to test the jal macro with -KPIC code.
+
+	.weak	weak_text_label
+
+	.ent	text_label
+text_label:
+	.frame	$sp, 0, $31
+	.set	noreorder
+	.cpload	$25
+	.cprestore	0
+	jal	$25
+	jal	$4, $25
+	jal	text_label
+	jal	weak_text_label
+	jal	external_text_label
+
+# Test j as well.
+	j	text_label
+	.set	reorder
+	nop
+
+	.end	text_label
+	.size	text_label, . - text_label
+
+# Force at least 8 (non-delay-slot) zero bytes, to make 'objdump' print ...
+	.align	2
+	.space	8
Index: binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/mips.exp
===================================================================
--- binutils-fsf-trunk-quilt.orig/gas/testsuite/gas/mips/mips.exp	2010-07-20 00:48:14.000000000 +0100
+++ binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/mips.exp	2010-07-20 00:48:16.000000000 +0100
@@ -465,6 +465,8 @@
     if $elf {
 	run_dump_test_arches "jal-svr4pic" \
 					[mips_arch_list_matching mips1]
+	run_dump_test_arches "jal-svr4pic-noreorder" \
+					[mips_arch_list_matching mips1]
     }
     if $elf { run_dump_test "jal-xgot" }
     run_list_test_arches "jal-range" "-32" [mips_arch_list_matching mips1]
Index: binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/mips1@jal-svr4pic-noreorder.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/mips1@jal-svr4pic-noreorder.d	2010-07-20 00:48:16.000000000 +0100
@@ -0,0 +1,48 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS jal-svr4pic noreorder
+#as: -32 -KPIC
+#source: jal-svr4pic-noreorder.s
+
+# Test the jal macro with -KPIC and `.set noreorder' (MIPS1).
+
+.*: +file format .*mips.*
+
+Disassembly of section \.text:
+[0-9a-f]+ <[^>]*> 3c1c0000 	lui	gp,0x0
+[ 	]*0: R_MIPS_HI16	_gp_disp
+[0-9a-f]+ <[^>]*> 279c0000 	addiu	gp,gp,0
+[ 	]*4: R_MIPS_LO16	_gp_disp
+[0-9a-f]+ <[^>]*> 0399e021 	addu	gp,gp,t9
+[0-9a-f]+ <[^>]*> afbc0000 	sw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 03202009 	jalr	a0,t9
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*28: R_MIPS_GOT16	.text
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 27390000 	addiu	t9,t9,0
+[ 	]*30: R_MIPS_LO16	.text
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*34: R_MIPS_JALR	text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*40: R_MIPS_CALL16	weak_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*48: R_MIPS_JALR	weak_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 8f990000 	lw	t9,0\(gp\)
+[ 	]*54: R_MIPS_CALL16	external_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 0320f809 	jalr	t9
+[ 	]*5c: R_MIPS_JALR	external_text_label
+[0-9a-f]+ <[^>]*> 00000000 	nop
+[0-9a-f]+ <[^>]*> 8fbc0000 	lw	gp,0\(sp\)
+[0-9a-f]+ <[^>]*> 1000ffe5 	b	0+0000 <text_label>
+[0-9a-f]+ <[^>]*> 00000000 	nop
+	\.\.\.
Index: binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/r3000@jal-svr4pic-noreorder.d
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ binutils-fsf-trunk-quilt/gas/testsuite/gas/mips/r3000@jal-svr4pic-noreorder.d	2010-07-20 00:48:16.000000000 +0100
@@ -0,0 +1,5 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: MIPS jal-svr4pic noreorder
+#as: -32 -KPIC
+#source: jal-svr4pic-noreorder.s
+#dump: mips1@jal-svr4pic-noreorder.d

Follow-Ups:
- Re: [PATCH 4/4] MIPS/GAS: Actual o32 SVR4 PIC JAL macro delay slot fix
  - From: Richard Sandiford

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