[PATCH] Enhance phiopt to handle BIT_AND_EXPR

["Zhenqiang Chen" <zhenqiang.chen@arm.com>]

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Hi,

The patch enhances phiopt to handle cases like:

  if (a == 0 && (...))
    return 0;
  return a;

Boot strap and no make check regression on X86-64 and ARM.

Is it OK for trunk?

Thanks!
-Zhenqiang

ChangeLog:
2013-09-30  Zhenqiang Chen  <zhenqiang.chen@linaro.org>

	* tree-ssa-phiopt.c (operand_equal_for_phi_arg_p_1): New.
	(value_replacement): Move a check to operand_equal_for_phi_arg_p_1.

testsuite/ChangeLog:
2013-09-30  Zhenqiang Chen  <zhenqiang.chen@linaro.org>

	* gcc.dg/tree-ssa/phi-opt-11.c: New test case.

[-- Attachment #2: phiopt.patch --]
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diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index 39d04ab..4752fe5 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -725,6 +725,80 @@ jump_function_from_stmt (tree *arg, gimple stmt)
   return false;
 }
 
+static int
+operand_equal_for_phi_arg_p_1 (const_tree arg0, const_tree arg1,
+			       enum tree_code *code, gimple cond)
+{
+  gimple def;
+  tree rhs, lhs;
+
+  if ((operand_equal_for_phi_arg_p (arg0, gimple_cond_lhs (cond))
+       && operand_equal_for_phi_arg_p (arg1, gimple_cond_rhs (cond)))
+      || (operand_equal_for_phi_arg_p (arg1, gimple_cond_lhs (cond))
+	  && operand_equal_for_phi_arg_p (arg0, gimple_cond_rhs (cond))))
+    return 1;
+
+  /* It handles case like
+
+     if (a == 0 && b > c)
+       return 0;
+     return a;
+
+     In gimple, the COND is like
+
+     t1 = a == 0
+     t2 = b > c
+     t3 = t1 & t2
+     if (t3 != 0)
+  */
+  lhs = gimple_cond_lhs (cond);
+  rhs = gimple_cond_rhs (cond);
+  if (*code != NE_EXPR || !integer_zerop (rhs)
+      || TREE_CODE (lhs) != SSA_NAME)
+    return 0;
+
+  def = SSA_NAME_DEF_STMT (lhs);
+  if (!is_gimple_assign (def) || gimple_assign_rhs_code (def) != BIT_AND_EXPR)
+    return 0;
+
+  if (TREE_CODE (gimple_assign_rhs1 (def)) == SSA_NAME)
+    {
+      gimple def1 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (def));
+      if (is_gimple_assign (def1) && gimple_assign_rhs_code (def1) == EQ_EXPR)
+	{
+	  tree op0 = gimple_assign_rhs1 (def1);
+	  tree op1 = gimple_assign_rhs2 (def1);
+	  if ((operand_equal_for_phi_arg_p (arg0, op0)
+	       && operand_equal_for_phi_arg_p (arg1, op1))
+	      || (operand_equal_for_phi_arg_p (arg0, op1)
+               && operand_equal_for_phi_arg_p (arg1, op0)))
+	    {
+	      *code = gimple_assign_rhs_code (def1);
+	      return 1;
+	    }
+	}
+    }
+  if (TREE_CODE (gimple_assign_rhs2 (def)) == SSA_NAME)
+    {
+      gimple def2 = SSA_NAME_DEF_STMT (gimple_assign_rhs2 (def));
+      if (is_gimple_assign (def2) && gimple_assign_rhs_code (def2) == EQ_EXPR)
+	{
+	  tree op0 = gimple_assign_rhs1 (def2);
+	  tree op1 = gimple_assign_rhs2 (def2);
+	  if ((operand_equal_for_phi_arg_p (arg0, op0)
+	       && operand_equal_for_phi_arg_p (arg1, op1))
+	      || (operand_equal_for_phi_arg_p (arg0, op1)
+               && operand_equal_for_phi_arg_p (arg1, op0)))
+	    {
+	      *code = gimple_assign_rhs_code (def2);
+	      return 1;
+	    }
+	}
+    }
+
+  return 0;
+}
+
 /*  The function value_replacement does the main work of doing the value
     replacement.  Return non-zero if the replacement is done.  Otherwise return
     0.  If we remove the middle basic block, return 2.
@@ -794,10 +868,7 @@ value_replacement (basic_block cond_bb, basic_block middle_bb,
      We now need to verify that the two arguments in the PHI node match
      the two arguments to the equality comparison.  */
 
-  if ((operand_equal_for_phi_arg_p (arg0, gimple_cond_lhs (cond))
-       && operand_equal_for_phi_arg_p (arg1, gimple_cond_rhs (cond)))
-      || (operand_equal_for_phi_arg_p (arg1, gimple_cond_lhs (cond))
-	  && operand_equal_for_phi_arg_p (arg0, gimple_cond_rhs (cond))))
+  if (operand_equal_for_phi_arg_p_1 (arg0, arg1, &code, cond))
     {
       edge e;
       tree arg;
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-11.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-11.c
new file mode 100644
index 0000000..ced1fc2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-11.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+int f(int a, int b, int c)
+{
+  if (a == 0 && b > c)
+   return 0;
+ return a;
+}
+
+/* { dg-final { scan-tree-dump-times "if" 0 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */