re PR target/79170 (memcmp builtin expansion sequence can overflow)

2017-01-27  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>

	PR target/79170
	* gcc.dg/memcmp-1.c: Improved to catch failures seen in PR 79170.

2017-01-27  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>

	PR target/79170
	* config/rs6000/altivec.md (*setb_internal): Rename to setb_signed.
	(setb_unsigned) New pattern for setb with CCUNS.
	* config/rs6000/rs6000.c (expand_block_compare): Use a different
	subfc./subfe sequence to avoid overflow problems.  Generate a
	shorter sequence with cmpld/setb for power9.
	* config/rs6000/rs6000.md (subf<mode>3_carry_dot2): Add a new pattern
	for generating subfc. instruction.
	(cmpstrsi): Add TARGET_POPCNTD predicate as the generate sequence
	now uses this instruction.

From-SVN: r245041

gcc/ChangeLog

+2017-01-30  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>
+
+	PR target/79170
+	* config/rs6000/altivec.md (*setb_internal): Rename to setb_signed.
+	(setb_unsigned) New pattern for setb with CCUNS.
+	* config/rs6000/rs6000.c (expand_block_compare): Use a different
+	subfc./subfe sequence to avoid overflow problems.  Generate a
+	shorter sequence with cmpld/setb for power9.
+	* config/rs6000/rs6000.md (subf<mode>3_carry_dot2): Add a new pattern
+	for generating subfc. instruction.
+	(cmpstrsi): Add TARGET_POPCNTD predicate as the generate sequence
+	now uses this instruction.
+
 2017-01-30  Ian Lance Taylor  <iant@google.com>
 
 	PR debug/79289

gcc/config/rs6000/altivec.md

@@ -3838,7 +3838,7 @@
 ;; Otherwise, set operand 0 to 0.  Note that the result stored into
 ;; register operand 0 is non-zero iff either the LT or GT bits are on
 ;; within condition register operand 1.
-(define_insn "*setb_internal"
+(define_insn "setb_signed"
    [(set (match_operand:SI 0 "gpc_reg_operand" "=r")
 	 (if_then_else:SI (lt (match_operand:CC 1 "cc_reg_operand" "y")
 			      (const_int 0))
@@ -3851,6 +3851,19 @@
   "setb %0,%1"
   [(set_attr "type" "logical")])
 
+(define_insn "setb_unsigned"
+   [(set (match_operand:SI 0 "gpc_reg_operand" "=r")
+	 (if_then_else:SI (ltu (match_operand:CCUNS 1 "cc_reg_operand" "y")
+			      (const_int 0))
+			  (const_int -1)
+			  (if_then_else (gtu (match_dup 1)
+					    (const_int 0))
+					(const_int 1)
+					(const_int 0))))]
+  "TARGET_P9_MISC"
+  "setb %0,%1"
+  [(set_attr "type" "logical")])
+
 ;; Test byte within two ranges.
 ;;
 ;; The bytes of operand 1 are organized as xx:xx:xx:vv, where xx

gcc/config/rs6000/rs6000.md

@@ -2068,6 +2068,35 @@
   "subfic %0,%1,%2"
   [(set_attr "type" "add")])
 
+(define_insn_and_split "subf<mode>3_carry_dot2"
+  [(set (match_operand:CC 3 "cc_reg_operand" "=x,?y")
+	(compare:CC (minus:P (match_operand:P 2 "gpc_reg_operand" "r,r")
+			       (match_operand:P 1 "gpc_reg_operand" "r,r"))
+		    (const_int 0)))
+   (set (match_operand:P 0 "gpc_reg_operand" "=r,r")
+	(minus:P (match_dup 2)
+		   (match_dup 1)))
+   (set (reg:P CA_REGNO)
+	(leu:P (match_dup 1)
+	       (match_dup 2)))]
+  "<MODE>mode == Pmode"
+  "@
+   subfc. %0,%1,%2
+   #"
+  "&& reload_completed && cc_reg_not_cr0_operand (operands[3], CCmode)"
+  [(parallel [(set (match_dup 0)
+                   (minus:P (match_dup 2)
+                            (match_dup 1)))
+              (set (reg:P CA_REGNO)
+                   (leu:P (match_dup 1)
+                          (match_dup 2)))])
+   (set (match_dup 3)
+        (compare:CC (match_dup 0)
+                    (const_int 0)))]
+  ""
+  [(set_attr "type" "add")
+   (set_attr "dot" "yes")
+   (set_attr "length" "4,8")])
 
 (define_insn "subf<mode>3_carry"
   [(set (match_operand:P 0 "gpc_reg_operand" "=r")
@@ -9146,11 +9175,11 @@
                            (match_operand:BLK 2)))
 	      (use (match_operand:SI 3))
 	      (use (match_operand:SI 4))])]
-  ""
+  "TARGET_POPCNTD"
 {
   if (expand_block_compare (operands))
     DONE;
-  else	
+  else
     FAIL;
 })
 

gcc/testsuite/ChangeLog

+2017-01-30  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>
+
+	PR target/79170
+	* gcc.dg/memcmp-1.c: Improved to catch failures seen in PR 79170.
+
 2017-01-30  Martin Sebor  <msebor@redhat.com>
 
 	PR testsuite/79293