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.
gcc/ChangeLog:
PR middle-end/107723
* convert.cc (convert_to_integer_1) [case BUILT_IN_TRUNC]: Break
early if !flag_fp_int_builtin_inexact.
gcc/testsuite/ChangeLog:
PR middle-end/107723
* gcc.dg/torture/builtin-fp-int-inexact-trunc.c: New test.
---
Bootstrapped and regtested on x86_64-linux-gnu. Ok for trunk?
gcc/convert.cc | 3 ++-
.../gcc.dg/torture/builtin-fp-int-inexact-trunc.c | 12 ++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/builtin-fp-int-inexact-trunc.c
diff --git a/gcc/convert.cc b/gcc/convert.cc
index 46c8bcb31f8..31f63ea783b 100644
--- a/gcc/convert.cc
+++ b/gcc/convert.cc
@@ -591,7 +591,8 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
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)
break;
return convert_to_integer_1 (type, CALL_EXPR_ARG (s_expr, 0),
dofold);
diff --git a/gcc/testsuite/gcc.dg/torture/builtin-fp-int-inexact-trunc.c
b/gcc/testsuite/gcc.dg/torture/builtin-fp-int-inexact-trunc.c
new file mode 100644
index 00000000000..09731183621
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/builtin-fp-int-inexact-trunc.c
@@ -0,0 +1,12 @@
+/* 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" } } */
--
2.43.0
