Adapt atomic compare and swap to ARMv8-M Baseline

2016-10-26  Thomas Preud'homme  <thomas.preudhomme@arm.com>

    gcc/
    * config/arm/sync.md (atomic_compare_and_swap<mode>_1): Add new ARMv8-M
    Baseline only alternatives to (i) hold store atomic success value in a
    return register rather than a scratch register, (ii) use a low register
    for it and to (iii) ensure the cbranchsi insn generated by the split
    respect the constraints of Thumb-1 cbranchsi4_insn and
    cbranchsi4_scratch.
    * config/arm/thumb1.md (cbranchsi4_insn): Add comment to indicate
    constraints must match those in atomic_compare_and_swap.
    (cbranchsi4_scratch): Likewise.

From-SVN: r241578

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5a79b961a1a71b855b22f65e71e74410a77fe261..12f9c0294758f7b1a6b40d6c29028e42c6b6beaf 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,15 @@
+2016-10-26  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+       * config/arm/sync.md (atomic_compare_and_swap<mode>_1): Add new ARMv8-M
+       Baseline only alternatives to (i) hold store atomic success value in a
+       return register rather than a scratch register, (ii) use a low register
+       for it and to (iii) ensure the cbranchsi insn generated by the split
+       respect the constraints of Thumb-1 cbranchsi4_insn and
+       cbranchsi4_scratch.
+       * config/arm/thumb1.md (cbranchsi4_insn): Add comment to indicate
+       constraints must match those in atomic_compare_and_swap.
+       (cbranchsi4_scratch): Likewise.
+
 2016-10-26  Thomas Preud'homme  <thomas.preudhomme@arm.com>
 
        * config/arm/arm.c (arm_expand_compare_and_swap): Add new bdst local

diff --git a/gcc/config/arm/sync.md b/gcc/config/arm/sync.md
index b4e0713108d9867d7226fad3241e46d1faf3172a..583b0af27d04ee8fba174e034a4c7b20760c38aa 100644 (file)
--- a/gcc/config/arm/sync.md
+++ b/gcc/config/arm/sync.md
@@ -189,21 +189,23 @@
   DONE;
 })
 
+;; 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")          ;; bool out
+  [(set (match_operand 0 "cc_register_operand" "=&c,&l,&l,&l")         ;; bool out
        (unspec_volatile:CC_Z [(const_int 0)] VUNSPEC_ATOMIC_CAS))
-   (set (match_operand:SI 1 "s_register_operand" "=&r")                ;; val out
+   (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")))  ;; memory
+         (match_operand:NARROW 2 "mem_noofs_operand" "+Ua,Ua,Ua,Ua"))) ;; memory
    (set (match_dup 2)
        (unspec_volatile:NARROW
-         [(match_operand:SI 3 "arm_add_operand" "rIL")         ;; expected
-          (match_operand:NARROW 4 "s_register_operand" "r")    ;; desired
+         [(match_operand:SI 3 "arm_add_operand" "rIL,lIL*h,J,*r")      ;; expected
+          (match_operand:NARROW 4 "s_register_operand" "r,r,r,r")      ;; desired
           (match_operand:SI 5 "const_int_operand")             ;; is_weak
           (match_operand:SI 6 "const_int_operand")             ;; mod_s
           (match_operand:SI 7 "const_int_operand")]            ;; mod_f
          VUNSPEC_ATOMIC_CAS))
-   (clobber (match_scratch:SI 8 "=&r"))]
+   (clobber (match_scratch:SI 8 "=&r,X,X,X"))]
   "<sync_predtab>"
   "#"
   "&& reload_completed"
@@ -211,27 +213,30 @@
   {
     arm_split_compare_and_swap (operands);
     DONE;
-  })
+  }
+  [(set_attr "arch" "32,v8mb,v8mb,v8mb")])
 
 (define_mode_attr cas_cmp_operand
   [(SI "arm_add_operand") (DI "cmpdi_operand")])
 (define_mode_attr cas_cmp_str
   [(SI "rIL") (DI "rDi")])
 
+;; 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")          ;; bool out
+  [(set (match_operand 0 "cc_register_operand" "=&c,&l,&l,&l")         ;; bool out
        (unspec_volatile:CC_Z [(const_int 0)] VUNSPEC_ATOMIC_CAS))
-   (set (match_operand:SIDI 1 "s_register_operand" "=&r")      ;; val out
-       (match_operand:SIDI 2 "mem_noofs_operand" "+Ua"))       ;; memory
+   (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)
        (unspec_volatile:SIDI
-         [(match_operand:SIDI 3 "<cas_cmp_operand>" "<cas_cmp_str>") ;; expect
-          (match_operand:SIDI 4 "s_register_operand" "r")      ;; desired
+         [(match_operand:SIDI 3 "<cas_cmp_operand>" "<cas_cmp_str>,lIL*h,J,*r") ;; expect
+          (match_operand:SIDI 4 "s_register_operand" "r,r,r,r")        ;; desired
           (match_operand:SI 5 "const_int_operand")             ;; is_weak
           (match_operand:SI 6 "const_int_operand")             ;; mod_s
           (match_operand:SI 7 "const_int_operand")]            ;; mod_f
          VUNSPEC_ATOMIC_CAS))
-   (clobber (match_scratch:SI 8 "=&r"))]
+   (clobber (match_scratch:SI 8 "=&r,X,X,X"))]
   "<sync_predtab>"
   "#"
   "&& reload_completed"
@@ -239,7 +244,8 @@
   {
     arm_split_compare_and_swap (operands);
     DONE;
-  })
+  }
+  [(set_attr "arch" "32,v8mb,v8mb,v8mb")])
 
 (define_insn_and_split "atomic_exchange<mode>"
   [(set (match_operand:QHSD 0 "s_register_operand" "=&r")      ;; output

diff --git a/gcc/config/arm/thumb1.md b/gcc/config/arm/thumb1.md
index cd98de7dcb40de483a9f93c0674bd216f4b0c56a..67f2878b45fe47abaaf24d97213613d1572dcd91 100644 (file)
--- a/gcc/config/arm/thumb1.md
+++ b/gcc/config/arm/thumb1.md
@@ -1059,6 +1059,9 @@
            (const_string "multiple")))]
 )
 
+;; Changes to the constraints of this pattern must be propagated to those of
+;; atomic compare_and_swap splitters in sync.md.  These must be at least as
+;; strict as the constraints here and aim to be as permissive.
 (define_insn "cbranchsi4_insn"
   [(set (pc) (if_then_else
              (match_operator 0 "arm_comparison_operator"
@@ -1120,6 +1123,9 @@
    (set_attr "type" "multiple")]
 )
 
+;; Changes to the constraints of this pattern must be propagated to those of
+;; atomic compare_and_swap splitters in sync.md.  These must be at least as
+;; strict as the constraints here and aim to be as permissive.
 (define_insn "cbranchsi4_scratch"
   [(set (pc) (if_then_else
              (match_operator 4 "arm_comparison_operator"