[PATCH, GCC/ARM, stage4] Set mode for success result of atomic compare and swap

[Thomas Preudhomme <thomas dot preudhomme at foss dot arm dot com>]

Hi,

Currently atomic_compare_and_swap<mode>_1 define_insn do not have a mode
set for the destination of the set indicating the success result of the
instruction. This is because the operand can be either a CC_Z register
(for 32-bit targets) or a SI register (for 16-bit Thumb targets). This
result in lack of checking for the mode.

This commit use a new CCSI iterator to solve this issue while avoiding
duplication of the patterns. The insn name are kept unique by using
attributes tied to the iterator (SIDI:mode and CCSI:arch) instead of
usign the builtin mode attribute. Expander arm_expand_compare_and_swap
is also adapted accordingly.

ChangeLog entry is as follows:

*** gcc/ChangeLog ***

2017-04-11  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	* config/arm/iterators.md (CCSI): New mode iterator.
	(arch): New mode attribute.
	* config/arm/sync.md (atomic_compare_and_swap<mode>_1): Rename into ...
	(atomic_compare_and_swap<CCSI:arch><NARROW:mode>_1): This and ...
	(atomic_compare_and_swap<CCSI:arch><SIDI:mode>_1): This.  Use CCSI
	code iterator for success result mode.
	* config/arm/arm.c (arm_expand_compare_and_swap): Adapt code to use
	the corresponding new insn generators.

Testing: arm-none-eabi cross-compiler built successfully for ARMv8-M
Mainline and Baseline without the lack of destination mode warning in
sync.md. Testsuite show no regression.

Is this ok for stage4?

Best regards,

Thomas

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index b24143e32e2f100000f3b150f7ed0df4fabb3cc8..cf628714507efd2b5a5ab5de97ef32fd45987d1f 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -28190,17 +28190,32 @@ arm_expand_compare_and_swap (rtx operands[])
       gcc_unreachable ();
     }
 
-  switch (mode)
+  if (TARGET_THUMB1)
     {
-    case QImode: gen = gen_atomic_compare_and_swapqi_1; break;
-    case HImode: gen = gen_atomic_compare_and_swaphi_1; break;
-    case SImode: gen = gen_atomic_compare_and_swapsi_1; break;
-    case DImode: gen = gen_atomic_compare_and_swapdi_1; break;
-    default:
-      gcc_unreachable ();
+      switch (mode)
+	{
+	case QImode: gen = gen_atomic_compare_and_swapt1qi_1; break;
+	case HImode: gen = gen_atomic_compare_and_swapt1hi_1; break;
+	case SImode: gen = gen_atomic_compare_and_swapt1si_1; break;
+	case DImode: gen = gen_atomic_compare_and_swapt1di_1; break;
+	default:
+	  gcc_unreachable ();
+	}
+    }
+  else
+    {
+      switch (mode)
+	{
+	case QImode: gen = gen_atomic_compare_and_swap32qi_1; break;
+	case HImode: gen = gen_atomic_compare_and_swap32hi_1; break;
+	case SImode: gen = gen_atomic_compare_and_swap32si_1; break;
+	case DImode: gen = gen_atomic_compare_and_swap32di_1; break;
+	default:
+	  gcc_unreachable ();
+	}
     }
 
-  bdst = TARGET_THUMB1 ? bval : gen_rtx_REG (CCmode, CC_REGNUM);
+  bdst = TARGET_THUMB1 ? bval : gen_rtx_REG (CC_Zmode, CC_REGNUM);
   emit_insn (gen (bdst, rval, mem, oldval, newval, is_weak, mod_s, mod_f));
 
   if (mode == QImode || mode == HImode)
diff --git a/gcc/config/arm/iterators.md b/gcc/config/arm/iterators.md
index e2e588688eb04c158d1c146bca12d84cfb5ff130..48992879a8eecc66eba913c2b9a7c5989c5c7bc6 100644
--- a/gcc/config/arm/iterators.md
+++ b/gcc/config/arm/iterators.md
@@ -45,6 +45,9 @@
 ;; A list of the 32bit and 64bit integer modes
 (define_mode_iterator SIDI [SI DI])
 
+;; A list of atomic compare and swap success return modes
+(define_mode_iterator CCSI [(CC_Z "TARGET_32BIT") (SI "TARGET_THUMB1")])
+
 ;; A list of modes which the VFP unit can handle
 (define_mode_iterator SDF [(SF "") (DF "TARGET_VFP_DOUBLE")])
 
@@ -411,6 +414,10 @@
 ;; Mode attributes
 ;;----------------------------------------------------------------------------
 
+;; Determine name of atomic compare and swap from success result mode.  This
+;; distinguishes between 16-bit Thumb and 32-bit Thumb/ARM.
+(define_mode_attr arch [(CC_Z "32") (SI "t1")])
+
 ;; Determine element size suffix from vector mode.
 (define_mode_attr MMX_char [(V8QI "b") (V4HI "h") (V2SI "w") (DI "d")])
 
diff --git a/gcc/config/arm/sync.md b/gcc/config/arm/sync.md
index 1f91b7364d5689145a10bbb193d54a0677b2fd36..b4b4f2e6815e7c31c9874c19af31e908107e6a62 100644
--- a/gcc/config/arm/sync.md
+++ b/gcc/config/arm/sync.md
@@ -191,9 +191,9 @@
 
 ;; Constraints of this pattern must be at least as strict as those of the
 ;; cbranchsi operations in thumb1.md and aim to be as permissive.
-(define_insn_and_split "atomic_compare_and_swap<mode>_1"
-  [(set (match_operand 0 "cc_register_operand" "=&c,&l,&l,&l")		;; bool out
-	(unspec_volatile:CC_Z [(const_int 0)] VUNSPEC_ATOMIC_CAS))
+(define_insn_and_split "atomic_compare_and_swap<CCSI:arch><NARROW:mode>_1"
+  [(set (match_operand:CCSI 0 "cc_register_operand" "=&c,&l,&l,&l")	;; bool out
+	(unspec_volatile:CCSI [(const_int 0)] VUNSPEC_ATOMIC_CAS))
    (set (match_operand:SI 1 "s_register_operand" "=&r,&l,&0,&l*h")	;; val out
 	(zero_extend:SI
 	  (match_operand:NARROW 2 "mem_noofs_operand" "+Ua,Ua,Ua,Ua")))	;; memory
@@ -223,9 +223,9 @@
 
 ;; Constraints of this pattern must be at least as strict as those of the
 ;; cbranchsi operations in thumb1.md and aim to be as permissive.
-(define_insn_and_split "atomic_compare_and_swap<mode>_1"
-  [(set (match_operand 0 "cc_register_operand" "=&c,&l,&l,&l")		;; bool out
-	(unspec_volatile:CC_Z [(const_int 0)] VUNSPEC_ATOMIC_CAS))
+(define_insn_and_split "atomic_compare_and_swap<CCSI:arch><SIDI:mode>_1"
+  [(set (match_operand:CCSI 0 "cc_register_operand" "=&c,&l,&l,&l")	;; bool out
+	(unspec_volatile:CCSI [(const_int 0)] VUNSPEC_ATOMIC_CAS))
    (set (match_operand:SIDI 1 "s_register_operand" "=&r,&l,&0,&l*h")	;; val out
 	(match_operand:SIDI 2 "mem_noofs_operand" "+Ua,Ua,Ua,Ua"))	;; memory
    (set (match_dup 2)