[PATCH, GAS/ARM] Allow assembly of IT blocks with AL condition

[Prakhar Bahuguna]

According to the ARMv7-M reference manual, section A7.7.37, the IT instruction
is permitted to accept the AL condition, provided the suffix does not have an
else. However, the assembler does not allow the AL condition to be specified at
all. This patch allows instructions to have the AL condition if they are within
an explicitly defined IT block with the matching condition.

2017-02-28  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>

gas/ChangeLog:

	* gas/config/tc-arm.c (it_fsm_pre_encode): Change conditional to first
	check for MANUAL_IT_BLOCK state, and update explanatory comment.
	* gas/testsuite/gas/arm/arm-it-al.d: New file.
	* gas/testsuite/gas/arm/arm-it-al.s: New file.

Testing done: Ran all gas regression tests, added new test to ensure IT with AL
condition assembles as expected with instructions outside of IT blocks
remaining unaffected.

Okay for master?

--

Prakhar Bahuguna
-------------- next part --------------
>From 284c841d6866c6d9129a239a79261df3557dba53 Mon Sep 17 00:00:00 2001
From: Prakhar Bahuguna <prakhar.bahuguna@arm.com>
Date: Tue, 28 Feb 2017 10:36:54 +0000
Subject: [PATCH] Allow assembly of IT blocks with AL condition

---
 gas/config/tc-arm.c               |  4 +++-
 gas/testsuite/gas/arm/arm-it-al.d | 13 +++++++++++++
 gas/testsuite/gas/arm/arm-it-al.s |  8 ++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 gas/testsuite/gas/arm/arm-it-al.d
 create mode 100644 gas/testsuite/gas/arm/arm-it-al.s

diff --git a/gas/config/tc-arm.c b/gas/config/tc-arm.c
index 60bda51070..a4d2d68e06 100644
--- a/gas/config/tc-arm.c
+++ b/gas/config/tc-arm.c
@@ -18013,6 +18013,8 @@ now_it_add_mask (int cond)
      1) md_assemble () calls it_fsm_pre_encode () before calling tencode (),
 	initializing the IT insn type with a generic initial value depending
 	on the inst.condition.
+	If the current state is in a manual IT block, the instruction is always
+	assumed to be an inside insn.
      2) During the tencode function, two things may happen:
 	a) The tencode function overrides the IT insn type by
 	   calling either set_it_insn_type (type) or set_it_insn_type_last ().
@@ -18058,7 +18060,7 @@ now_it_add_mask (int cond)
 static void
 it_fsm_pre_encode (void)
 {
-  if (inst.cond != COND_ALWAYS)
+  if (now_it.state == MANUAL_IT_BLOCK || inst.cond != COND_ALWAYS)
     inst.it_insn_type = INSIDE_IT_INSN;
   else
     inst.it_insn_type = OUTSIDE_IT_INSN;
diff --git a/gas/testsuite/gas/arm/arm-it-al.d b/gas/testsuite/gas/arm/arm-it-al.d
new file mode 100644
index 0000000000..2c4c0da857
--- /dev/null
+++ b/gas/testsuite/gas/arm/arm-it-al.d
@@ -0,0 +1,13 @@
+#name: ARM IT instruction with AL condition
+#as: -mthumb -march=armv7a
+#objdump: -dr --prefix-addresses --show-raw-insn
+#skip: *-*-*coff *-*-pe *-*-wince *-*-*aout* *-*-netbsd *-*-riscix*
+
+.*: +file format .*arm.*
+
+
+Disassembly of section .text:
+0+0 <.text> bfe4 *	itt	al
+0+2 <.text\+0x2> 2000 *	moval	r0, #0
+0+4 <.text\+0x4> 3001 *	addal	r0, #1
+0+6 <.text\+0x6> f04f 0000 *	mov.w	r0, #0
diff --git a/gas/testsuite/gas/arm/arm-it-al.s b/gas/testsuite/gas/arm/arm-it-al.s
new file mode 100644
index 0000000000..b52aa5aa84
--- /dev/null
+++ b/gas/testsuite/gas/arm/arm-it-al.s
@@ -0,0 +1,8 @@
+	# Check that IT accepts AL condition
+	.text
+	.syntax unified
+
+	itt	al
+	moval	r0, #0
+	addal	r0, #1
+	moval	r0, #0
-- 
2.11.0