re PR tree-optimization/66726 (missed optimization, factor conversion out of COND_EXPR)

        PR middle-end/66726
        * tree-ssa-phiopt.c (factor_out_conditional_conversion):
        Tune heuristic from PR71016 to allow MIN / MAX.
        * testsuite/gcc.dg/tree-ssa/pr66726-4.c: New testcase.

From-SVN: r272911

gcc/ChangeLog

+2019-07-01  Joern Rennecke  <joern.rennecke@riscy-ip.com>
+
+	PR middle-end/66726
+	* tree-ssa-phiopt.c (factor_out_conditional_conversion):
+	Tune heuristic from PR71016 to allow MIN / MAX.
+	* testsuite/gcc.dg/tree-ssa/pr66726-4.c: New testcase.
+
 2019-07-01  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* config/rs6000/rs6000.md (ieee_128bit_vsx_abs<mode>2): Make this a

gcc/testsuite/gcc.dg/tree-ssa/pr66726-4.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-phiopt1-details" } */
+
+#define SAT(x) (x < 0 ? 0 : (x > 255 ? 255 : x))
+
+void
+foo (unsigned char *p, int i)
+{
+  *p = SAT (i);
+}
+
+/* { dg-final { scan-tree-dump-times "COND_EXPR .*and PHI .*converted to straightline code" 1 "phiopt1" } } */

gcc/tree-ssa-phiopt.c

@@ -504,7 +504,24 @@ factor_out_conditional_conversion (edge e0, edge e1, gphi *phi,
 		  gsi = gsi_for_stmt (arg0_def_stmt);
 		  gsi_prev_nondebug (&gsi);
 		  if (!gsi_end_p (gsi))
-		    return NULL;
+		    {
+		      if (gassign *assign
+			    = dyn_cast <gassign *> (gsi_stmt (gsi)))
+			{
+			  tree lhs = gimple_assign_lhs (assign);
+			  enum tree_code ass_code
+			    = gimple_assign_rhs_code (assign);
+			  if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
+			    return NULL;
+			  if (lhs != gimple_assign_rhs1 (arg0_def_stmt))
+			    return NULL;
+			  gsi_prev_nondebug (&gsi);
+			  if (!gsi_end_p (gsi))
+			    return NULL;
+			}
+		      else
+			return NULL;
+		    }
 		  gsi = gsi_for_stmt (arg0_def_stmt);
 		  gsi_next_nondebug (&gsi);
 		  if (!gsi_end_p (gsi))