re PR tree-optimization/88797 (Unneeded branch added when function is inlined…

re PR tree-optimization/88797 (Unneeded branch added when function is inlined (function runs faster if not inlined))

	PR tree-optimization/88797
	* gimple-ssa-split-paths (is_feasible_trace): Reject cases where the
	PHI feeds a conditional on the RHS of an assignment.

	PR tree-optimization/88797
	* g++.dg/tree-ssa/pr88797.C: New test.

From-SVN: r270775

gcc/ChangeLog

+2019-05-01  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/88797
+	* gimple-ssa-split-paths (is_feasible_trace): Reject cases where the
+	PHI feeds a conditional on the RHS of an assignment.
+
 2019-04-30  Andrew Waterman  <andrew@sifive.com>
 	    Jim Wilson  <jimw@sifive.com>
 

gcc/gimple-ssa-split-paths.c

@@ -264,8 +264,12 @@ is_feasible_trace (basic_block bb)
 	  if (is_gimple_debug (stmt))
 	    continue;
 	  /* If there's a use in the joiner this might be a CSE/DCE
-	     opportunity.  */
-	  if (gimple_bb (stmt) == bb)
+	     opportunity, but not if the use is in a conditional
+	     which makes this a likely if-conversion candidate.  */
+	  if (gimple_bb (stmt) == bb
+	      && (!is_gimple_assign (stmt)
+		  || (TREE_CODE_CLASS (gimple_assign_rhs_code (stmt))
+		      != tcc_comparison)))
 	    {
 	      found_useful_phi = true;
 	      break;

gcc/testsuite/ChangeLog

+2019-05-01  Jeff Law  <law@redhat.com>
+
+	PR tree-optimization/90037
+	* g++.dg/tree-ssa/pr88797.C: New test.
+
 2019-05-01  Nathan Sidwell  <nathan@acm.org>
 
 	* g++.dg/cpp0x/decltype9.C: Adjust expected diagnostics.

gcc/testsuite/g++.dg/tree-ssa/pr88797.C

+/* { dg-do compile } */
+/* { dg-options "-O3 -fdump-tree-split-paths-details" } */
+
+
+void use(unsigned);
+bool f(unsigned x, unsigned y) {
+    return x < 1111 + (y <= 2222);
+}
+void test_f(unsigned x, unsigned y) {
+    for (unsigned i = 0; i < 3333; ++i)
+        use(f(x++, y++));
+}
+
+/* { dg-final { scan-tree-dump-not "Duplicating join block" "split-paths" } } */
+/* { dg-final { scan-tree-dump-times "Block . is a join that does not expose" 1 "split-paths" } } */
+