[PATCH] Fix gcc.dg/uninit-pred-8_b.c fallout on GCC 8 branch (PR89551)

[Richard Biener <rguenther at suse dot de>]

The following backports support for --param logical-op-non-short-circuit
to the GCC 8 branch (but not all the testsuite adjustments) and adjusts
the gcc.dg/uninit-pred-8_b.c as was done on trunk for the PR89497 fix.

Boostrap / regtest running on x86_64-unknown-linux-gnu.

Richard.

2019-03-15  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	2019-03-06  Richard Biener  <rguenther@suse.de>

	PR testsuite/89551
	* gcc.dg/uninit-pred-8_b.c: Force logical-op-non-short-circuit
	the way that makes the testcase PASS.

	2018-11-30  Jakub Jelinek  <jakub@redhat.com>

	PR testsuite/85368
	* params.def (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT): New param.
	* tree-ssa-ifcombine.c (ifcombine_ifandif): If
	--param logical-op-non-short-circuit is present, override
	LOGICAL_OP_NON_SHORT_CIRCUIT value from the param.
	* fold-const.c (fold_range_test, fold_truth_andor): Likewise.

Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c	(revision 269701)
+++ gcc/fold-const.c	(working copy)
@@ -5515,12 +5515,15 @@ fold_range_test (location_t loc, enum tr
   /* On machines where the branch cost is expensive, if this is a
      short-circuited branch and the underlying object on both sides
      is the same, make a non-short-circuit operation.  */
-  else if (LOGICAL_OP_NON_SHORT_CIRCUIT
-	   && !flag_sanitize_coverage
-	   && lhs != 0 && rhs != 0
-	   && (code == TRUTH_ANDIF_EXPR
-	       || code == TRUTH_ORIF_EXPR)
-	   && operand_equal_p (lhs, rhs, 0))
+  bool logical_op_non_short_circuit = LOGICAL_OP_NON_SHORT_CIRCUIT;
+  if (PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT) != -1)
+    logical_op_non_short_circuit
+      = PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT);
+  if (logical_op_non_short_circuit
+      && !flag_sanitize_coverage
+      && lhs != 0 && rhs != 0
+      && (code == TRUTH_ANDIF_EXPR || code == TRUTH_ORIF_EXPR)
+      && operand_equal_p (lhs, rhs, 0))
     {
       /* If simple enough, just rewrite.  Otherwise, make a SAVE_EXPR
 	 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
@@ -8165,7 +8168,11 @@ fold_truth_andor (location_t loc, enum t
   if ((tem = fold_truth_andor_1 (loc, code, type, arg0, arg1)) != 0)
     return tem;
 
-  if (LOGICAL_OP_NON_SHORT_CIRCUIT
+  bool logical_op_non_short_circuit = LOGICAL_OP_NON_SHORT_CIRCUIT;
+  if (PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT) != -1)
+    logical_op_non_short_circuit
+      = PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT);
+  if (logical_op_non_short_circuit
       && !flag_sanitize_coverage
       && (code == TRUTH_AND_EXPR
           || code == TRUTH_ANDIF_EXPR
Index: gcc/params.def
===================================================================
--- gcc/params.def	(revision 269701)
+++ gcc/params.def	(working copy)
@@ -1331,6 +1331,11 @@ DEFPARAM(PARAM_AVOID_FMA_MAX_BITS,
 	 "Maximum number of bits for which we avoid creating FMAs.",
 	 0, 0, 512)
 
+DEFPARAM(PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT,
+	 "logical-op-non-short-circuit",
+	 "True if a non-short-circuit operation is optimal.",
+	 -1, -1, 1)
+
 /*
 
 Local variables:
Index: gcc/testsuite/gcc.dg/uninit-pred-8_b.c
===================================================================
--- gcc/testsuite/gcc.dg/uninit-pred-8_b.c	(revision 269701)
+++ gcc/testsuite/gcc.dg/uninit-pred-8_b.c	(working copy)
@@ -1,6 +1,7 @@
-
 /* { dg-do compile } */
-/* { dg-options "-Wuninitialized -O2" } */
+/* ???  Jump threading makes a mess of the logical-op-non-short-circuit=0 case
+   so force it our way.  */
+/* { dg-options "-Wuninitialized -O2 --param logical-op-non-short-circuit=1" } */
 
 int g;
 void bar();
Index: gcc/tree-ssa-ifcombine.c
===================================================================
--- gcc/tree-ssa-ifcombine.c	(revision 269701)
+++ gcc/tree-ssa-ifcombine.c	(working copy)
@@ -40,6 +40,7 @@ along with GCC; see the file COPYING3.
 #include "gimplify-me.h"
 #include "tree-cfg.h"
 #include "tree-ssa.h"
+#include "params.h"
 
 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
@@ -556,7 +557,11 @@ ifcombine_ifandif (basic_block inner_con
 	{
 	  tree t1, t2;
 	  gimple_stmt_iterator gsi;
-	  if (!LOGICAL_OP_NON_SHORT_CIRCUIT || flag_sanitize_coverage)
+	  bool logical_op_non_short_circuit = LOGICAL_OP_NON_SHORT_CIRCUIT;
+	  if (PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT) != -1)
+	    logical_op_non_short_circuit
+	      = PARAM_VALUE (PARAM_LOGICAL_OP_NON_SHORT_CIRCUIT);
+	  if (!logical_op_non_short_circuit || flag_sanitize_coverage)
 	    return false;
 	  /* Only do this optimization if the inner bb contains only the conditional. */
 	  if (!gsi_one_before_end_p (gsi_start_nondebug_after_labels_bb (inner_cond_bb)))