[gcc r12-7048] Disable new 1/X optimization with -fnon-call-exceptions

[gcc r12-7048] Disable new 1/X optimization with -fnon-call-exceptions

[Eric Botcazou]

https://gcc.gnu.org/g:bd14cdceb9c6f4800e25a9fbca635a1d4c06fd32

commit r12-7048-gbd14cdceb9c6f4800e25a9fbca635a1d4c06fd32
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Fri Feb 4 12:03:49 2022 +0100

    Disable new 1/X optimization with -fnon-call-exceptions
    
    The trapping behavior of the operation needs to be preserved when the
    -fnon-call-exceptions switch is in effect.  This also adds the same
    guards to similar optimizations.
    
    gcc/
            PR tree-optimization/104356
            * match.pd (X / bool_range_Y is X): Add guard.
            (X / X is one): Likewise.
            (X / abs (X) is X < 0 ? -1 : 1): Likewise.
            (X / -X is -1): Likewise.
            (1 / X -> X == 1): Likewise.

Diff:
---
 gcc/match.pd | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/gcc/match.pd b/gcc/match.pd
index b942cb2930a..10ff867e854 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -401,27 +401,35 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  /* X / bool_range_Y is X.  */ 
  (simplify
   (div @0 SSA_NAME@1)
-  (if (INTEGRAL_TYPE_P (type) && ssa_name_has_boolean_range (@1))
+  (if (INTEGRAL_TYPE_P (type)
+       && ssa_name_has_boolean_range (@1)
+       && !flag_non_call_exceptions)
    @0))
  /* X / X is one.  */
  (simplify
   (div @0 @0)
   /* But not for 0 / 0 so that we can get the proper warnings and errors.
      And not for _Fract types where we can't build 1.  */
-  (if (!integer_zerop (@0) && !ALL_FRACT_MODE_P (TYPE_MODE (type)))
+  (if (!ALL_FRACT_MODE_P (TYPE_MODE (type))
+       && !integer_zerop (@0)
+       && (!flag_non_call_exceptions || tree_expr_nonzero_p (@0)))
    { build_one_cst (type); }))
  /* X / abs (X) is X < 0 ? -1 : 1.  */
  (simplify
    (div:C @0 (abs @0))
    (if (INTEGRAL_TYPE_P (type)
-	&& TYPE_OVERFLOW_UNDEFINED (type))
+	&& TYPE_OVERFLOW_UNDEFINED (type)
+	&& !integer_zerop (@0)
+	&& (!flag_non_call_exceptions || tree_expr_nonzero_p (@0)))
     (cond (lt @0 { build_zero_cst (type); })
           { build_minus_one_cst (type); } { build_one_cst (type); })))
  /* X / -X is -1.  */
  (simplify
    (div:C @0 (negate @0))
    (if ((INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
-	&& TYPE_OVERFLOW_UNDEFINED (type))
+	&& TYPE_OVERFLOW_UNDEFINED (type)
+	&& !integer_zerop (@0)
+	&& (!flag_non_call_exceptions || tree_expr_nonzero_p (@0)))
     { build_minus_one_cst (type); })))
 
 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
@@ -443,8 +451,9 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (simplify
  (trunc_div integer_onep@0 @1)
  (if (INTEGRAL_TYPE_P (type)
+      && TYPE_PRECISION (type) > 1
       && !integer_zerop (@1)
-      && TYPE_PRECISION (type) > 1)
+      && (!flag_non_call_exceptions || tree_expr_nonzero_p (@1)))
   (if (TYPE_UNSIGNED (type))
    (convert (eq:boolean_type_node @1 { build_one_cst (type); }))
    (with { tree utype = unsigned_type_for (type); }