compare-elim.c (try_eliminate_compare): Canonicalize operation with embedded…

compare-elim.c (try_eliminate_compare): Canonicalize operation with embedded compare to [(set (reg:CCM) (compare:CCM...

	* compare-elim.c (try_eliminate_compare): Canonicalize
	operation with embedded compare to
	[(set (reg:CCM) (compare:CCM (operation) (immediate)))
	 (set (reg) (operation)].

	* config/i386/i386.c (TARGET_FLAGS_REGNUM): New define.

From-SVN: r247992

gcc/ChangeLog

 2017-05-12  Uros Bizjak  <ubizjak@gmail.com>
 
+	* compare-elim.c (try_eliminate_compare): Canonicalize
+	operation with embedded compare to
+	[(set (reg:CCM) (compare:CCM (operation) (immediate)))
+	 (set (reg) (operation)].
+
+	* config/i386/i386.c (TARGET_FLAGS_REGNUM): New define.
+
+2017-05-12  Uros Bizjak  <ubizjak@gmail.com>
+
 	PR target/80723
 	* config/i386/i386.c (ix86_rtx_cost) [case PLUS]: Ignore the
 	cost of adding a carry flag for ADC instruction.

gcc/compare-elim.c

@@ -45,9 +45,9 @@ along with GCC; see the file COPYING3.  If not see
    (3) If an insn of form (2) can usefully set the flags, there is
        another pattern of the form
 
-	[(set (reg) (operation)
-	 (set (reg:CCM) (compare:CCM (operation) (immediate)))]
-
+	[(set (reg:CCM) (compare:CCM (operation) (immediate)))
+	 (set (reg) (operation)]
+	 
        The mode CCM will be chosen as if by SELECT_CC_MODE.
 
    Note that unlike NOTICE_UPDATE_CC, we do not handle memory operands.
@@ -582,7 +582,7 @@ equivalent_reg_at_start (rtx reg, rtx_insn *end, rtx_insn *start)
 static bool
 try_eliminate_compare (struct comparison *cmp)
 {
-  rtx x, flags, in_a, in_b, cmp_src;
+  rtx flags, in_a, in_b, cmp_src;
 
   /* We must have found an interesting "clobber" preceding the compare.  */
   if (cmp->prev_clobber == NULL)
@@ -628,7 +628,8 @@ try_eliminate_compare (struct comparison *cmp)
      Validate that PREV_CLOBBER itself does in fact refer to IN_A.  Do
      recall that we've already validated the shape of PREV_CLOBBER.  */
   rtx_insn *insn = cmp->prev_clobber;
-  x = XVECEXP (PATTERN (insn), 0, 0);
+
+  rtx x = XVECEXP (PATTERN (insn), 0, 0);
   if (rtx_equal_p (SET_DEST (x), in_a))
     cmp_src = SET_SRC (x);
 
@@ -666,13 +667,24 @@ try_eliminate_compare (struct comparison *cmp)
     flags = gen_rtx_REG (cmp->orig_mode, targetm.flags_regnum);
 
   /* Generate a new comparison for installation in the setter.  */
-  x = copy_rtx (cmp_src);
-  x = gen_rtx_COMPARE (GET_MODE (flags), x, in_b);
-  x = gen_rtx_SET (flags, x);
+  rtx y = copy_rtx (cmp_src);
+  y = gen_rtx_COMPARE (GET_MODE (flags), y, in_b);
+  y = gen_rtx_SET (flags, y);
+
+  /* Canonicalize instruction to:
+     [(set (reg:CCM) (compare:CCM (operation) (immediate)))
+      (set (reg) (operation)]  */
 
+  rtvec v = rtvec_alloc (2);
+  RTVEC_ELT (v, 0) = y;
+  RTVEC_ELT (v, 1) = x;
+  
+  rtx pat = gen_rtx_PARALLEL (VOIDmode, v);
+  
   /* Succeed if the new instruction is valid.  Note that we may have started
      a change group within maybe_select_cc_mode, therefore we must continue. */
-  validate_change (insn, &XVECEXP (PATTERN (insn), 0, 1), x, true);
+  validate_change (insn, &PATTERN (insn), pat, true);
+  
   if (!apply_change_group ())
     return false;
 

gcc/config/i386/i386.c

@@ -51826,6 +51826,8 @@ ix86_run_selftests (void)
 #undef TARGET_ADDRESS_COST
 #define TARGET_ADDRESS_COST ix86_address_cost
 
+#undef TARGET_FLAGS_REGNUM
+#define TARGET_FLAGS_REGNUM FLAGS_REG
 #undef TARGET_FIXED_CONDITION_CODE_REGS
 #define TARGET_FIXED_CONDITION_CODE_REGS ix86_fixed_condition_code_regs
 #undef TARGET_CC_MODES_COMPATIBLE