From 0ea52812a8a6c60c580529d1d3dbe144f8e6fc2f Mon Sep 17 00:00:00 2001
From: Eric Botcazou <ebotcazou@adacore.com>
Date: Mon, 19 Nov 2018 10:25:35 +0000
Subject: compare-elim.c (struct comparison): Add not_in_a field.

	* compare-elim.c (struct comparison): Add not_in_a field.
	(is_not): New static function.
	(strip_not): Likewise.
	(conforming_compare): Handle a NOT in the first operand.
	(can_eliminate_compare): Likewise.
	(find_comparison_dom_walker::before_dom_children): Likewise.
	(try_eliminate_compare): Likewise.
	* config/visium/visium.md (negsi2_insn_set_carry): Turn into...
	(neg<mode>2_insn_set_carry): ...this and add missing NEG operation.

From-SVN: r266268
---
 gcc/compare-elim.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

(limited to 'gcc/compare-elim.c')

diff --git a/gcc/compare-elim.c b/gcc/compare-elim.c
index 8afbe76..f38e576 100644
--- a/gcc/compare-elim.c
+++ b/gcc/compare-elim.c
@@ -123,10 +123,32 @@ struct comparison
 
   /* True if its inputs are still valid at the end of the block.  */
   bool inputs_valid;
+
+  /* Whether IN_A is wrapped in a NOT before being compared.  */
+  bool not_in_a;
 };
   
 static vec<comparison *> all_compares;
 
+/* Return whether X is a NOT unary expression.  */
+
+static bool
+is_not (rtx x)
+{
+  return GET_CODE (x) == NOT;
+}
+
+/* Strip a NOT unary expression around X, if any.  */
+
+static rtx
+strip_not (rtx x)
+{
+  if (is_not (x))
+    return XEXP (x, 0);
+
+  return x;
+}
+
 /* Look for a "conforming" comparison, as defined above.  If valid, return
    the rtx for the COMPARE itself.  */
 
@@ -147,7 +169,7 @@ conforming_compare (rtx_insn *insn)
   if (!REG_P (dest) || REGNO (dest) != targetm.flags_regnum)
     return NULL;
 
-  if (!REG_P (XEXP (src, 0)))
+  if (!REG_P (strip_not (XEXP (src, 0))))
     return NULL;
 
   if (CONSTANT_P (XEXP (src, 1)) || REG_P (XEXP (src, 1)))
@@ -278,10 +300,13 @@ can_eliminate_compare (rtx compare, rtx eh_note, struct comparison *cmp)
     return false;
 
   /* Make sure the compare is redundant with the previous.  */
-  if (!rtx_equal_p (XEXP (compare, 0), cmp->in_a)
+  if (!rtx_equal_p (strip_not (XEXP (compare, 0)), cmp->in_a)
       || !rtx_equal_p (XEXP (compare, 1), cmp->in_b))
     return false;
 
+  if (is_not (XEXP (compare, 0)) != cmp->not_in_a)
+    return false;
+
   /* New mode must be compatible with the previous compare mode.  */
   machine_mode new_mode
     = targetm.cc_modes_compatible (GET_MODE (compare), cmp->orig_mode);
@@ -365,8 +390,9 @@ find_comparison_dom_walker::before_dom_children (basic_block bb)
 	  last_cmp = XCNEW (struct comparison);
 	  last_cmp->insn = insn;
 	  last_cmp->prev_clobber = last_clobber;
-	  last_cmp->in_a = XEXP (src, 0);
+	  last_cmp->in_a = strip_not (XEXP (src, 0));
 	  last_cmp->in_b = XEXP (src, 1);
+	  last_cmp->not_in_a = is_not (XEXP (src, 0));
 	  last_cmp->eh_note = eh_note;
 	  last_cmp->orig_mode = GET_MODE (src);
 	  if (last_cmp->in_b == const0_rtx
@@ -837,7 +863,9 @@ 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.  */
-  rtx y = copy_rtx (cmp_a);
+  rtx y = cmp->not_in_a
+	  ? gen_rtx_NOT (GET_MODE (cmp_a), copy_rtx (cmp_a))
+	  : copy_rtx (cmp_a);
   y = gen_rtx_COMPARE (GET_MODE (flags), y, copy_rtx (cmp_b));
   y = gen_rtx_SET (flags, y);
 
-- 
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