[gcc r13-8816] AVR: target/115317 - Make isinf(-Inf) return -1.

[Georg-Johann Lay]

https://gcc.gnu.org/g:b45d7281c1b4eb2cf61280b9f7064229b7ca7581

commit r13-8816-gb45d7281c1b4eb2cf61280b9f7064229b7ca7581
Author: Georg-Johann Lay <avr@gjlay.de>
Date:   Sat Jun 1 12:46:31 2024 +0200

    AVR: target/115317 - Make isinf(-Inf) return -1.
    
            PR target/115317
    libgcc/config/avr/libf7/
            * libf7-asm.sx (__isinf): Map -Inf to -1.
    
    gcc/testsuite/
            * gcc.target/avr/torture/pr115317-isinf.c: New test.
    
    (cherry picked from commit f12454278dc725fec3520a5d870e967d79292ee6)

Diff:
---
 .../gcc.target/avr/torture/pr115317-isinf.c        | 55 ++++++++++++++++++++++
 libgcc/config/avr/libf7/libf7-asm.sx               | 19 +++++---
 2 files changed, 67 insertions(+), 7 deletions(-)

diff --git a/gcc/testsuite/gcc.target/avr/torture/pr115317-isinf.c b/gcc/testsuite/gcc.target/avr/torture/pr115317-isinf.c
new file mode 100644
index 00000000000..10f7b553fb9
--- /dev/null
+++ b/gcc/testsuite/gcc.target/avr/torture/pr115317-isinf.c
@@ -0,0 +1,55 @@
+/* { dg-do run { target { ! avr_tiny } } } */
+
+extern int isinff (float);
+extern int isinf (double);
+extern int isinfl (long double);
+
+int tst_isinf (float x, int val)
+{
+  double y;
+  long double z;
+
+  __asm ("" : "+r"(x));
+  if (isinff (x) != val)
+    __builtin_exit (__LINE__);
+
+  y = x;
+  __asm ("" : "+r"(y));
+  if (isinf (y) != val)
+  __builtin_exit (__LINE__);
+
+  z = x;
+  __asm ("" : "+r"(z));
+  if (isinfl (z) != val)
+  __builtin_exit (__LINE__);
+}
+
+static float make_f (__UINT32_TYPE__ i)
+{
+  float f;
+  __builtin_memcpy (&f, &i, 4);
+  return f;
+}
+
+int main (void)
+{
+  tst_isinf (__builtin_huge_valf(), 1);
+  tst_isinf (-__builtin_huge_valf(), -1);
+  tst_isinf (__builtin_nanf(""), 0);
+  tst_isinf (0.0f, 0);
+  tst_isinf (-0.0f, 0);
+  tst_isinf (1.0f, 0);
+  tst_isinf (-1.0f, 0);
+  tst_isinf (make_f (0x7f800000), 1);
+  tst_isinf (make_f (0xff800000), -1);
+  tst_isinf (make_f (0x7f7fffff), 0);
+  tst_isinf (make_f (0xff7fffff), 0);
+  tst_isinf (make_f (0x7f800001), 0);
+  tst_isinf (make_f (0xff800001), 0);
+  tst_isinf (make_f (0x00800000), 0);
+  tst_isinf (make_f (0x80800000), 0);
+  tst_isinf (make_f (0x00400000), 0);
+  tst_isinf (make_f (0x80400000), 0);
+  
+  return 0;
+}
diff --git a/libgcc/config/avr/libf7/libf7-asm.sx b/libgcc/config/avr/libf7/libf7-asm.sx
index df315d35c73..84790d2f52d 100644
--- a/libgcc/config/avr/libf7/libf7-asm.sx
+++ b/libgcc/config/avr/libf7/libf7-asm.sx
@@ -1639,19 +1639,24 @@ _ENDF __copysign
 
 
 #ifdef F7MOD_D_isinf_
+;;; +Inf  ->  +1
+;;; -Inf  ->  -1
 _DEFUN __isinf
     DALIAS isinf
     LALIAS isinfl
+    ;; Save sign for later
+    push    R25
     F7call  class_D
+    pop     TMP
+    ldi     R24,    0
+    ldi     R25,    0
     ;; Inf: T = Z = 1.
-    brtc 0f
+    brtc 0f                     ; ordinary number
+    brne 0f                     ; Nan
     ldi     R24,    1
-    breq 1f
-0:
-    clr     R24
-1:
-    clr     R25
-    ret
+    sbrc    TMP,    7
+    sbiw    R24,    2
+0:  ret
 _ENDF __isinf
 #endif /* F7MOD_D_isinf_ */