Allow COND_EXPR and VEC_COND_EXPR condtions to trap

Right now gimplifier does not allow VEC_COND_EXPR's condition to trap
and introduces a temporary if this could happen, for example, generating

  _5 = _4 > { 2.0e+0, 2.0e+0, 2.0e+0, 2.0e+0 };
  _6 = VEC_COND_EXPR <_5, { -1, -1, -1, -1 }, { 0, 0, 0, 0 }>;

from GENERIC

  VEC_COND_EXPR < (*b > { 2.0e+0, 2.0e+0, 2.0e+0, 2.0e+0 }) ,
                  { -1, -1, -1, -1 } ,
		  { 0, 0, 0, 0 } >

This is not necessary and makes the resulting GIMPLE harder to analyze.
Change the gimplifier so as to allow COND_EXPR and VEC_COND_EXPR
conditions to trap.

This patch takes special care to avoid introducing trapping comparisons
in GIMPLE_COND.  They are not allowed, because they would require 3
outgoing edges (then, else and EH), which is awkward to say the least.
Therefore, computations of such conditions should live in their own basic
blocks.

gcc/ChangeLog:

2019-10-07  Ilya Leoshkevich  <iii@linux.ibm.com>

	PR target/77918
	* gimple-expr.c (gimple_cond_get_ops_from_tree): Assert that the
	caller passes a non-trapping condition.
	(is_gimple_condexpr): Allow trapping conditions.
	(is_gimple_condexpr_1): New helper function.
	(is_gimple_condexpr_for_cond): New function, acts like old
	is_gimple_condexpr.
	* gimple-expr.h (is_gimple_condexpr_for_cond): New function.
	* gimple.c (gimple_could_trap_p_1): Handle COND_EXPR and
	VEC_COND_EXPR. Fix an issue with statements like i = (fp < 1.).
	* gimplify.c (gimplify_cond_expr): Use
	is_gimple_condexpr_for_cond.
	(gimplify_expr): Allow is_gimple_condexpr_for_cond.
	* tree-eh.c (operation_could_trap_p): Assert on COND_EXPR and
	VEC_COND_EXPR.
	(tree_could_trap_p): Handle COND_EXPR and VEC_COND_EXPR.
	* tree-ssa-forwprop.c (forward_propagate_into_gimple_cond): Use
	is_gimple_condexpr_for_cond, remove pointless tmp check
	(forward_propagate_into_cond): Remove pointless tmp check.

From-SVN: r276659

7 files changed, 72 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2702146ef4b..922ca5d0bd9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,25 @@
+2019-10-07  Ilya Leoshkevich  <iii@linux.ibm.com>
+
+	PR target/77918
+	* gimple-expr.c (gimple_cond_get_ops_from_tree): Assert that the
+	caller passes a non-trapping condition.
+	(is_gimple_condexpr): Allow trapping conditions.
+	(is_gimple_condexpr_1): New helper function.
+	(is_gimple_condexpr_for_cond): New function, acts like old
+	is_gimple_condexpr.
+	* gimple-expr.h (is_gimple_condexpr_for_cond): New function.
+	* gimple.c (gimple_could_trap_p_1): Handle COND_EXPR and
+	VEC_COND_EXPR. Fix an issue with statements like i = (fp < 1.).
+	* gimplify.c (gimplify_cond_expr): Use
+	is_gimple_condexpr_for_cond.
+	(gimplify_expr): Allow is_gimple_condexpr_for_cond.
+	* tree-eh.c (operation_could_trap_p): Assert on COND_EXPR and
+	VEC_COND_EXPR.
+	(tree_could_trap_p): Handle COND_EXPR and VEC_COND_EXPR.
+	* tree-ssa-forwprop.c (forward_propagate_into_gimple_cond): Use
+	is_gimple_condexpr_for_cond, remove pointless tmp check
+	(forward_propagate_into_cond): Remove pointless tmp check.
+
 2019-10-07 Vladislav Ivanishin  <vlad@ispras.ru>
 
 	* gimple-iterator.h (gsi_next_nonvirtual_phi): Change the semantics to
diff --git a/gcc/gimple-expr.c b/gcc/gimple-expr.c
index 4082828e198..1738af186d7 100644
--- a/gcc/gimple-expr.c
+++ b/gcc/gimple-expr.c
@@ -574,6 +574,7 @@ gimple_cond_get_ops_from_tree (tree cond, enum tree_code *code_p,
 	      || TREE_CODE (cond) == TRUTH_NOT_EXPR
 	      || is_gimple_min_invariant (cond)
 	      || SSA_VAR_P (cond));
+  gcc_checking_assert (!tree_could_throw_p (cond));
 
   extract_ops_from_tree (cond, code_p, lhs_p, rhs_p);
 
@@ -605,17 +606,33 @@ is_gimple_lvalue (tree t)
 	  || TREE_CODE (t) == BIT_FIELD_REF);
 }
 
-/*  Return true if T is a GIMPLE condition.  */
+/* Helper for is_gimple_condexpr and is_gimple_condexpr_for_cond.  */
 
-bool
-is_gimple_condexpr (tree t)
+static bool
+is_gimple_condexpr_1 (tree t, bool allow_traps)
 {
   return (is_gimple_val (t) || (COMPARISON_CLASS_P (t)
-				&& !tree_could_throw_p (t)
+				&& (allow_traps || !tree_could_throw_p (t))
 				&& is_gimple_val (TREE_OPERAND (t, 0))
 				&& is_gimple_val (TREE_OPERAND (t, 1))));
 }
 
+/* Return true if T is a GIMPLE condition.  */
+
+bool
+is_gimple_condexpr (tree t)
+{
+  return is_gimple_condexpr_1 (t, true);
+}
+
+/* Like is_gimple_condexpr, but does not allow T to trap.  */
+
+bool
+is_gimple_condexpr_for_cond (tree t)
+{
+  return is_gimple_condexpr_1 (t, false);
+}
+
 /* Return true if T is a gimple address.  */
 
 bool
diff --git a/gcc/gimple-expr.h b/gcc/gimple-expr.h
index 1ad1432bd17..0925aeb0f57 100644
--- a/gcc/gimple-expr.h
+++ b/gcc/gimple-expr.h
@@ -41,6 +41,7 @@ extern void gimple_cond_get_ops_from_tree (tree, enum tree_code *, tree *,
 					   tree *);
 extern bool is_gimple_lvalue (tree);
 extern bool is_gimple_condexpr (tree);
+extern bool is_gimple_condexpr_for_cond (tree);
 extern bool is_gimple_address (const_tree);
 extern bool is_gimple_invariant_address (const_tree);
 extern bool is_gimple_ip_invariant_address (const_tree);
diff --git a/gcc/gimple.c b/gcc/gimple.c
index 8e828a5f169..a874c29454c 100644
--- a/gcc/gimple.c
+++ b/gcc/gimple.c
@@ -2149,10 +2149,22 @@ gimple_could_trap_p_1 (gimple *s, bool include_mem, bool include_stores)
       return false;
 
     case GIMPLE_ASSIGN:
-      t = gimple_expr_type (s);
       op = gimple_assign_rhs_code (s);
+
+      /* For COND_EXPR and VEC_COND_EXPR only the condition may trap.  */
+      if (op == COND_EXPR || op == VEC_COND_EXPR)
+	return tree_could_trap_p (gimple_assign_rhs1 (s));
+
+      /* For comparisons we need to check rhs operand types instead of rhs type
+         (which is BOOLEAN_TYPE).  */
+      if (TREE_CODE_CLASS (op) == tcc_comparison)
+	t = TREE_TYPE (gimple_assign_rhs1 (s));
+      else
+	t = gimple_expr_type (s);
+
       if (get_gimple_rhs_class (op) == GIMPLE_BINARY_RHS)
 	div = gimple_assign_rhs2 (s);
+
       return (operation_could_trap_p (op, FLOAT_TYPE_P (t),
 				      (INTEGRAL_TYPE_P (t)
 				       && TYPE_OVERFLOW_TRAPS (t)),
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 88d6571976f..836706961f3 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -4142,8 +4142,8 @@ gimplify_cond_expr (tree *expr_p, gimple_seq *pre_p, fallback_t fallback)
   /* Now do the normal gimplification.  */
 
   /* Gimplify condition.  */
-  ret = gimplify_expr (&TREE_OPERAND (expr, 0), pre_p, NULL, is_gimple_condexpr,
-		       fb_rvalue);
+  ret = gimplify_expr (&TREE_OPERAND (expr, 0), pre_p, NULL,
+		       is_gimple_condexpr_for_cond, fb_rvalue);
   if (ret == GS_ERROR)
     return GS_ERROR;
   gcc_assert (TREE_OPERAND (expr, 0) != NULL_TREE);
@@ -12976,6 +12976,7 @@ gimplify_expr (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
   else if (gimple_test_f == is_gimple_val
            || gimple_test_f == is_gimple_call_addr
            || gimple_test_f == is_gimple_condexpr
+	   || gimple_test_f == is_gimple_condexpr_for_cond
            || gimple_test_f == is_gimple_mem_rhs
            || gimple_test_f == is_gimple_mem_rhs_or_call
            || gimple_test_f == is_gimple_reg_rhs
diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 1aba7333631..7a028735d4e 100644
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2523,6 +2523,10 @@ operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv,
   bool honor_snans = fp_operation && flag_signaling_nans != 0;
   bool handled;
 
+  /* This function cannot tell whether or not COND_EXPR and VEC_COND_EXPR could
+     trap, because that depends on the respective condition op.  */
+  gcc_assert (op != COND_EXPR && op != VEC_COND_EXPR);
+
   if (TREE_CODE_CLASS (op) != tcc_comparison
       && TREE_CODE_CLASS (op) != tcc_unary
       && TREE_CODE_CLASS (op) != tcc_binary)
@@ -2610,6 +2614,10 @@ tree_could_trap_p (tree expr)
   if (!expr)
     return false;
 
+  /* For COND_EXPR and VEC_COND_EXPR only the condition may trap.  */
+  if (TREE_CODE (expr) == COND_EXPR || TREE_CODE (expr) == VEC_COND_EXPR)
+    expr = TREE_OPERAND (expr, 0);
+
   code = TREE_CODE (expr);
   t = TREE_TYPE (expr);
 
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index a1e22c93631..fe55ca958b4 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -527,9 +527,10 @@ forward_propagate_into_gimple_cond (gcond *stmt)
   tmp = forward_propagate_into_comparison_1 (stmt, code,
 					     boolean_type_node,
 					     rhs1, rhs2);
-  if (tmp)
+  if (tmp
+      && is_gimple_condexpr_for_cond (tmp))
     {
-      if (dump_file && tmp)
+      if (dump_file)
 	{
 	  fprintf (dump_file, "  Replaced '");
 	  print_gimple_expr (dump_file, stmt, 0);
@@ -607,7 +608,7 @@ forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
   if (tmp
       && is_gimple_condexpr (tmp))
     {
-      if (dump_file && tmp)
+      if (dump_file)
 	{
 	  fprintf (dump_file, "  Replaced '");
 	  print_generic_expr (dump_file, cond);