On ARM soft-float, the float to double conversion doesn't convert a sNaN
to qNaN as the IEEE Std 754 standard mandates:
"Under default exception handling, any operation signaling an invalid
operation exception and for which a floating-point result is to be
delivered shall deliver a quiet NaN."
Given the soft float ARM code ignores exceptions and always provides a
result, a float to double conversion of a signaling NaN should return a
quiet NaN. Fix this in extendsfdf2.
gcc/ChangeLog:
PR target/59833
* config/arm/ieee754-df.S (extendsfdf2): Convert sNaN to qNaN.
gcc/testsuite/ChangeLog:
* gcc.dg/pr59833.c: New testcase.
---
gcc/testsuite/gcc.dg/pr59833.c | 18 ++++++++++++++++++
libgcc/config/arm/ieee754-df.S | 10 +++++++---
2 files changed, 25 insertions(+), 3 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr59833.c
diff --git a/gcc/testsuite/gcc.dg/pr59833.c b/gcc/testsuite/gcc.dg/pr59833.c
new file mode 100644
index 0000000..e0e4ed5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr59833.c
@@ -0,0 +1,18 @@
+/* { dg-do run { target { *-*-linux* *-*-gnu* } } } */
+/* { dg-options "-O0 -lm" } */
+/* { dg-require-effective-target issignaling } */
+
+#define _GNU_SOURCE
+#include <math.h>
+
+int main (void)
+{
+ float sNaN = __builtin_nansf ("");
+ double x = (double) sNaN;
+ if (issignaling(x))
+ {
+ __builtin_abort();
+ }
+
+ return 0;
+}
diff --git a/libgcc/config/arm/ieee754-df.S b/libgcc/config/arm/ieee754-df.S
index a2aac70..1ecaa9d 100644
--- a/libgcc/config/arm/ieee754-df.S
+++ b/libgcc/config/arm/ieee754-df.S
@@ -507,11 +507,15 @@ ARM_FUNC_ALIAS aeabi_f2d extendsfdf2
eorne xh, xh, #0x38000000 @ fixup exponent otherwise.
RETc(ne) @ and return it.
- teq r2, #0 @ if actually 0
- do_it ne, e
- teqne r3, #0xff000000 @ or INF or NAN
+ bics r2, r2, #0xff000000 @ isolate mantissa
+ do_it eq @ if 0, that is ZERO or INF,
RETc(eq) @ we are done already.
+ teq r3, #0xff000000 @ check for NAN
+ do_it eq, t
+ orreq xh, xh, #0x00080000 @ change to quiet NAN
+ RETc(eq) @ and return it.
+
@ value was denormalized. We can normalize it now.
do_push {r4, r5, lr}
.cfi_adjust_cfa_offset 12 @ CFA is now sp + previousOffset + 12
--
Aurelien Jarno GPG: 4096R/1DDD8C9B
aurel...@aurel32.net http://www.aurel32.net
