ifcombine: For short circuit case, allow 2 convert defining statements [PR85605]

r0-126134-g5d2a9da9a7f7c1 added support for circuiting and combing the ifs
into using either AND or OR. But it only allowed the inner condition
basic block having the conditional only. This changes to allow up to 2 defining
statements as long as they are just integer to integer conversions for
either the lhs or rhs of the conditional.

This should allow to use ccmp on aarch64 and x86_64 (APX) slightly more than before.

Boootstrapped and tested on x86_64-linux-gnu.

	PR tree-optimization/85605

gcc/ChangeLog:

	* tree-ssa-ifcombine.cc (can_combine_bbs_with_short_circuit): New function.
	(ifcombine_ifandif): Use can_combine_bbs_with_short_circuit
	instead of checking if iterator is one before the last statement.

gcc/testsuite/ChangeLog:

	* g++.dg/tree-ssa/ifcombine-ccmp-1.C: New test.
	* gcc.dg/tree-ssa/ssa-ifcombine-ccmp-7.c: New test.
	* gcc.dg/tree-ssa/ssa-ifcombine-ccmp-8.c: New test.
	* gcc.dg/tree-ssa/ssa-ifcombine-ccmp-9.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

gcc/testsuite/g++.dg/tree-ssa/ifcombine-ccmp-1.C

@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -fdump-tree-optimized --param logical-op-non-short-circuit=1" } */
+
+/* PR tree-optimization/85605 */
+#include <stdint.h>
+
+template<class T,class T2>
+inline bool cmp(T a, T2 b) {
+  return a<0 ? true : T2(a) < b;
+}
+
+template<class T,class T2>
+inline bool cmp2(T a, T2 b) {
+  return (a<0) | (T2(a) < b);
+}
+
+bool f(int a, int b) {
+    return cmp(int64_t(a), unsigned(b));
+}
+
+bool f2(int a, int b) {
+    return cmp2(int64_t(a), unsigned(b));
+}
+
+
+/* Both of these functions should be optimized to the same, and have an | in them. */
+/* { dg-final { scan-tree-dump-times " \\\| " 2 "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-ccmp-7.c

@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -fdump-tree-optimized --param logical-op-non-short-circuit=1" } */
+
+/* PR tree-optimization/85605 */
+/* Like ssa-ifcombine-ccmp-1.c but with conversion from unsigned to signed in the
+   inner bb which should be able to move too. */
+
+int t (int a, unsigned b)
+{
+  if (a > 0)
+  {
+    signed t = b;
+    if (t > 0)
+      return 0;
+  }
+  return 1;
+}
+/* { dg-final { scan-tree-dump "\&" "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-ccmp-8.c

@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -fdump-tree-optimized --param logical-op-non-short-circuit=1" } */
+
+/* PR tree-optimization/85605 */
+/* Like ssa-ifcombine-ccmp-2.c but with conversion from unsigned to signed in the
+   inner bb which should be able to move too. */
+
+int t (int a, unsigned b)
+{
+  if (a > 0)
+    goto L1;
+  signed t = b;
+  if (t > 0)
+    goto L1;
+  return 0;
+L1:
+  return 1;
+}
+/* { dg-final { scan-tree-dump "\|" "optimized" } } */

gcc/testsuite/gcc.dg/tree-ssa/ssa-ifcombine-ccmp-9.c

@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -g -fdump-tree-optimized --param logical-op-non-short-circuit=1" } */
+
+/* PR tree-optimization/85605 */
+/* Like ssa-ifcombine-ccmp-1.c but with conversion from short to int in the
+   inner bb which should be able to move too. */
+
+int t (int a, short b, int c)
+{
+  if (a > 0)
+  {
+    if (c == b)
+      return 0;
+  }
+  return 1;
+}
+/* { dg-final { scan-tree-dump "\&" "optimized" } } */

gcc/tree-ssa-ifcombine.cc

@@ -776,6 +776,36 @@ ifcombine_replace_cond (gcond *inner_cond, bool inner_inv,
   return true;
 }
 
+/* Returns true if inner_cond_bb contains just the condition or 1/2 statements
+   that define lhs or rhs with an integer conversion. */
+
+static bool
+can_combine_bbs_with_short_circuit (basic_block inner_cond_bb, tree lhs, tree rhs)
+{
+  gimple_stmt_iterator gsi;
+  gsi = gsi_start_nondebug_after_labels_bb (inner_cond_bb);
+  /* If only the condition, this should be allowed. */
+  if (gsi_one_before_end_p (gsi))
+    return true;
+  /* Can have up to 2 statements defining each of lhs/rhs. */
+  for (int i = 0; i < 2; i++)
+    {
+      gimple *stmt = gsi_stmt (gsi);
+      if (!is_gimple_assign (stmt)
+	  || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt)))
+	return false;
+      /* The defining statement needs to match either the lhs or rhs of
+	 the condition. */
+      if (lhs != gimple_assign_lhs (stmt)
+	  && rhs != gimple_assign_lhs (stmt))
+	return false;
+      gsi_next_nondebug (&gsi);
+      if (gsi_one_before_end_p (gsi))
+	return true;
+    }
+  return false;
+}
+
 /* If-convert on a and pattern with a common else block.  The inner
    if is specified by its INNER_COND_BB, the outer by OUTER_COND_BB.
    inner_inv, outer_inv indicate whether the conditions are inverted.
@@ -951,8 +981,11 @@ ifcombine_ifandif (basic_block inner_cond_bb, bool inner_inv,
 	      = param_logical_op_non_short_circuit;
 	  if (!logical_op_non_short_circuit || sanitize_coverage_p ())
 	    return false;
-	  /* Only do this optimization if the inner bb contains only the conditional. */
+	  /* 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)))
+	     or there is one or 2 statements which are nop conversion for the comparison. */
+	  if (!can_combine_bbs_with_short_circuit (inner_cond_bb,
+						   gimple_cond_lhs (inner_cond),
+						   gimple_cond_rhs (inner_cond)))
 	    return false;
 	  t1 = fold_build2_loc (gimple_location (inner_cond),
 				inner_cond_code,