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Re: [PATCH] Make ARM GAS accept valid STR instruction
On 08/25/2010 10:58 AM, Daniel Jacobowitz wrote:
On Mon, Aug 23, 2010 at 11:38:59PM +0800, Jie Zhang wrote:
On 08/21/2010 05:03 AM, Daniel Jacobowitz wrote:
On Wed, Aug 18, 2010 at 04:28:07PM +0800, Jie Zhang wrote:
`str r0,[pc,#4]' is a valid instruction although the use of PC is
deprecated. But currently GAS rejects this instruction. This patch
should fix it. Tested using GAS testsuite for arm-none-eabi target.
Is it OK?
Where (on what architectures) is the use of PC deprecated? It's
documented as fine in the ARM v5 reference; I do not think we should
warn unconditionally, but then, some other code in gas does. At least
check warn_on_deprecated.
swp{b} warns only of armv6 or later, that might be the right model here.
Thanks! That's a good idea. I checked the manuals. It's deprecated
since ARMv7-A. So I changed my patch accordingly. The new patch is
attached. In the new patch, I just removed the valid instruction from
the test and inserted a blank line to keep the line numbers of the
following lines unchanged to avoid massive line number changes in
test dump file. Compared to the last version of the patch, I added
the valid str instruction to the new test added by the this patch.
Tested GAS for arm-none-eabi, no regressions found.
Is it OK now?
Yes. Please tweak the architecture test though: it's deprecated for
all ARM v7. It doesn't matter for M-profile because the ARM
instruction set is missing there, but v7-R is the same as v7-A here.
Thanks. The patch attached is what I have committed.
--
Jie Zhang
CodeSourcery
* config/tc-arm.c (encode_arm_addr_mode_2): Fix
BAD_PC_ADDRESSING condition.
testsuite/
* gas/arm/ldst-pc.d: New test.
* gas/arm/ldst-pc.s: New test.
* gas/arm/sp-pc-validations-bad.s: `str r0,[pc,#4]' is valid.
* gas/arm/sp-pc-validations-bad.l: Adjust accordingly.
Index: config/tc-arm.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-arm.c,v
retrieving revision 1.452
diff -u -p -r1.452 tc-arm.c
--- config/tc-arm.c 8 Jul 2010 22:40:26 -0000 1.452
+++ config/tc-arm.c 25 Aug 2010 05:22:17 -0000
@@ -6819,11 +6819,18 @@ encode_arm_addr_mode_2 (int i, bfd_boole
if (is_pc && !inst.reloc.pc_rel)
{
const bfd_boolean is_load = ((inst.instruction & LOAD_BIT) != 0);
- /* BAD_PC_ADDRESSING Condition =
- is_load => is_t
- which becomes !is_load || is_t. */
- constraint ((!is_load || is_t),
+
+ /* If is_t is TRUE, it's called from do_ldstt. ldrt/strt
+ cannot use PC in addressing.
+ PC cannot be used in writeback addressing, either. */
+ constraint ((is_t || inst.operands[i].writeback),
BAD_PC_ADDRESSING);
+
+ /* Use of PC in str is deprecated for ARMv7-A. */
+ if (warn_on_deprecated
+ && !is_load
+ && ARM_CPU_HAS_FEATURE (selected_cpu, arm_ext_v7))
+ as_warn (_("use of PC in this instruction is deprecated"));
}
if (inst.reloc.type == BFD_RELOC_UNUSED)
Index: testsuite/gas/arm/ldst-pc.d
===================================================================
RCS file: testsuite/gas/arm/ldst-pc.d
diff -N testsuite/gas/arm/ldst-pc.d
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gas/arm/ldst-pc.d 25 Aug 2010 05:22:17 -0000
@@ -0,0 +1,16 @@
+#objdump: -dr --prefix-addresses --show-raw-insn
+#name: ARM load/store with pc base register
+#as: -mno-warn-deprecated
+
+# Test the standard ARM instructions:
+
+.*: +file format .*arm.*
+
+Disassembly of section .text:
+0+000 <[^>]*> e51f1008 ldr r1, \[pc, #-8\] ; 0+000 <[^>]*>
+0+004 <[^>]*> e79f1002 ldr r1, \[pc, r2\]
+0+008 <[^>]*> f55ff008 pld \[pc, #-8\] ; 0+008 <[^>]*>
+0+00c <[^>]*> f7dff001 pld \[pc, r1\]
+0+010 <[^>]*> f45ff008 pli \[pc, #-8\] ; 0+010 <[^>]*>
+0+014 <[^>]*> f6dff001 pli \[pc, r1\]
+0+018 <[^>]*> e58f1004 str r1, \[pc, #4\] ; 0+024 <[^>]*>
Index: testsuite/gas/arm/ldst-pc.s
===================================================================
RCS file: testsuite/gas/arm/ldst-pc.s
diff -N testsuite/gas/arm/ldst-pc.s
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ testsuite/gas/arm/ldst-pc.s 25 Aug 2010 05:22:17 -0000
@@ -0,0 +1,15 @@
+@ Test file for ARM load/store instructions with pc as the base register
+
+ .text
+ .syntax unified
+ .align 2
+ ldr r1, [pc, #-8]
+ ldr r1, [pc, r2]
+
+ pld [pc, #-8]
+ pld [pc, r1]
+
+ pli [pc, #-8]
+ pli [pc, r1]
+
+ str r1, [pc, #4]
Index: testsuite/gas/arm/sp-pc-validations-bad.l
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/arm/sp-pc-validations-bad.l,v
retrieving revision 1.1
diff -u -p -r1.1 sp-pc-validations-bad.l
--- testsuite/gas/arm/sp-pc-validations-bad.l 12 Feb 2010 20:15:13 -0000 1.1
+++ testsuite/gas/arm/sp-pc-validations-bad.l 25 Aug 2010 05:22:17 -0000
@@ -101,7 +101,6 @@
[^:]*:158: Error: r15 not allowed here -- `ldrt pc,\[r0\],r1,LSL#4'
[^:]*:159: Error: cannot use register index with PC-relative addressing -- `ldrt r0,\[pc\],r1,LSL#4'
[^:]*:160: Error: cannot use register index with PC-relative addressing -- `ldrt r0,\[r1\],pc,LSL#4'
-[^:]*:165: Error: cannot use register index with PC-relative addressing -- `str r0,\[pc,#4\]'
[^:]*:166: Error: cannot use register index with PC-relative addressing -- `str r0,\[pc\],#4'
[^:]*:167: Error: cannot use register index with PC-relative addressing -- `str r0,\[pc,#4\]!'
[^:]*:170: Error: cannot use register index with PC-relative addressing -- `str r0,\[r1,pc,LSL#4\]'
Index: testsuite/gas/arm/sp-pc-validations-bad.s
===================================================================
RCS file: /cvs/src/src/gas/testsuite/gas/arm/sp-pc-validations-bad.s,v
retrieving revision 1.1
diff -u -p -r1.1 sp-pc-validations-bad.s
--- testsuite/gas/arm/sp-pc-validations-bad.s 12 Feb 2010 20:15:13 -0000 1.1
+++ testsuite/gas/arm/sp-pc-validations-bad.s 25 Aug 2010 05:22:17 -0000
@@ -159,11 +159,11 @@ ldrt pc,[r0],r1, LSL #4 @ ditto
ldrt r0,[pc],r1, LSL #4 @ ditto
ldrt r0,[r1],pc, LSL #4 @ ditto
+
@ Stores, ARM ================================================================
@ STR (immediate, ARM)
-str r0,[pc,#4] @ Unpredictable
-str r0,[pc],#4 @ ditto
+str r0,[pc],#4 @ Unpredictable
str r0,[pc,#4]! @ ditto
@ STR (register)