[PATCH][ARM] Merge negdi2 patterns

Wilco Dijkstra Wilco.Dijkstra@arm.com
Wed Dec 14 16:37:00 GMT 2016


    

ping



From: Wilco Dijkstra
Sent: 30 November 2016 17:39
To: GCC Patches
Cc: nd; Bernd Edlinger
Subject: [PATCH][ARM] Merge negdi2 patterns
    
The negdi2 patterns for ARM and Thumb-2 are duplicated because Thumb-2
doesn't support RSC with an immediate.  We can however emulate RSC with
zero using a shifted SBC.  If we add this to subsi3_carryin the negdi
patterns can be merged, simplifying things a bit (eg. if changing when to split
for PR77308).  This should generate identical code in all cases.

ChangeLog:
2016-11-30  Wilco Dijkstra  <wdijkstr@arm.com>

        * gcc/config/arm/arm.md (subsi3_carryin): Add Thumb-2 RSC #0.
        (arm_negdi2) Rename to negdi2, allow on Thumb-2.
        * gcc/config/arm/thumb2.md (thumb2_negdi2): Remove pattern.

--
diff --git a/gcc/config/arm/arm.md b/gcc/config/arm/arm.md
index 2035fa5861d876771aef9fb391bcb01b877cf148..eb79d1376e1fb3df1eabddde22aa93ab6fec94ea 100644
--- a/gcc/config/arm/arm.md
+++ b/gcc/config/arm/arm.md
@@ -1128,19 +1128,20 @@
 )
 
 (define_insn "*subsi3_carryin"
-  [(set (match_operand:SI 0 "s_register_operand" "=r,r")
-        (minus:SI (minus:SI (match_operand:SI 1 "reg_or_int_operand" "r,I")
-                            (match_operand:SI 2 "s_register_operand" "r,r"))
+  [(set (match_operand:SI 0 "s_register_operand" "=r,r,r")
+        (minus:SI (minus:SI (match_operand:SI 1 "reg_or_int_operand" "r,I,Pz")
+                            (match_operand:SI 2 "s_register_operand" "r,r,r"))
                   (ltu:SI (reg:CC_C CC_REGNUM) (const_int 0))))]
   "TARGET_32BIT"
   "@
    sbc%?\\t%0, %1, %2
-   rsc%?\\t%0, %2, %1"
+   rsc%?\\t%0, %2, %1
+   sbc%?\\t%0, %2, %2, lsl #1"
   [(set_attr "conds" "use")
-   (set_attr "arch" "*,a")
+   (set_attr "arch" "*,a,t2")
    (set_attr "predicable" "yes")
    (set_attr "predicable_short_it" "no")
-   (set_attr "type" "adc_reg,adc_imm")]
+   (set_attr "type" "adc_reg,adc_imm,alu_shift_imm")]
 )
 
 (define_insn "*subsi3_carryin_const"
@@ -4731,12 +4732,13 @@
 
 ;; The constraints here are to prevent a *partial* overlap (where %Q0 == %R1).
 ;; The first alternative allows the common case of a *full* overlap.
-(define_insn_and_split "*arm_negdi2"
+(define_insn_and_split "*negdi2"
   [(set (match_operand:DI         0 "s_register_operand" "=r,&r")
         (neg:DI (match_operand:DI 1 "s_register_operand"  "0,r")))
    (clobber (reg:CC CC_REGNUM))]
-  "TARGET_ARM"
-  "#"   ; "rsbs\\t%Q0, %Q1, #0\;rsc\\t%R0, %R1, #0"
+  "TARGET_32BIT"
+  "#"   ; rsbs %Q0, %Q1, #0; rsc %R0, %R1, #0          (ARM)
+       ; negs %Q0, %Q1    ; sbc %R0, %R1, %R1, lsl #1 (Thumb-2)
   "&& reload_completed"
   [(parallel [(set (reg:CC CC_REGNUM)
                    (compare:CC (const_int 0) (match_dup 1)))
diff --git a/gcc/config/arm/thumb2.md b/gcc/config/arm/thumb2.md
index affcd832b72b7d358347e7370265be492866bb90..d9c530a48878923683485933c5640ffe80908401 100644
--- a/gcc/config/arm/thumb2.md
+++ b/gcc/config/arm/thumb2.md
@@ -125,32 +125,6 @@
    (set_attr "type" "multiple")]
 )
 
-;; Thumb-2 does not have rsc, so use a clever trick with shifter operands.
-(define_insn_and_split "*thumb2_negdi2"
-  [(set (match_operand:DI         0 "s_register_operand" "=&r,r")
-       (neg:DI (match_operand:DI 1 "s_register_operand"  "?r,0")))
-   (clobber (reg:CC CC_REGNUM))]
-  "TARGET_THUMB2"
-  "#" ; negs\\t%Q0, %Q1\;sbc\\t%R0, %R1, %R1, lsl #1
-  "&& reload_completed"
-  [(parallel [(set (reg:CC CC_REGNUM)
-                  (compare:CC (const_int 0) (match_dup 1)))
-             (set (match_dup 0) (minus:SI (const_int 0) (match_dup 1)))])
-   (set (match_dup 2) (minus:SI (minus:SI (match_dup 3)
-                                          (ashift:SI (match_dup 3)
-                                                     (const_int 1)))
-                                (ltu:SI (reg:CC_C CC_REGNUM) (const_int 0))))]
-  {
-    operands[2] = gen_highpart (SImode, operands[0]);
-    operands[0] = gen_lowpart (SImode, operands[0]);
-    operands[3] = gen_highpart (SImode, operands[1]);
-    operands[1] = gen_lowpart (SImode, operands[1]);
-  }
-  [(set_attr "conds" "clob")
-   (set_attr "length" "8")
-   (set_attr "type" "multiple")]
-)
        


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