With -fno-fp-int-builtin-inexact, trunc is not allowed to raise
FE_INEXACT and it should produce an integral result (if the input is not
NaN or Inf). Thus FE_INEXACT should not be raised.
But (int)x may raise FE_INEXACT when x is a non-integer, non-NaN, and
non-Inf value. C23 recommends to do so in a footnote.
Thus we should not simplify (int)trunc(x) to (int)x if
-fno-fp-int-builtin-inexact is in-effect.
gcc/ChangeLog:
PR middle-end/107723
* convert.cc (convert_to_integer_1) [case BUILT_IN_TRUNC]: Break
early if !flag_fp_int_builtin_inexact and flag_trapping_math.
gcc/testsuite/ChangeLog:
PR middle-end/107723
* gcc.dg/torture/builtin-fp-int-inexact-trunc.c: New test.
CASE_FLT_FN (BUILT_IN_TRUNC):
CASE_FLT_FN_FLOATN_NX (BUILT_IN_TRUNC):
if (call_expr_nargs (s_expr) != 1
- || !SCALAR_FLOAT_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (s_expr, 0))))
+ || !SCALAR_FLOAT_TYPE_P (TREE_TYPE (CALL_EXPR_ARG (s_expr, 0)))
+ || (!flag_fp_int_builtin_inexact && flag_trapping_math))
break;
return convert_to_integer_1 (type, CALL_EXPR_ARG (s_expr, 0),
dofold);
--- /dev/null
+/* Test -fno-fp-int-builtin-inexact. */
+/* { dg-do compile } */
+/* { dg-options "-fno-fp-int-builtin-inexact -fdump-tree-original" } */
+
+long
+x (double y)
+{
+ return __builtin_trunc (y);
+}
+
+/* Optimization should not discard the __builtin_trunc call. */
+/* { dg-final { scan-tree-dump "__builtin_trunc" "original" } } */