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authorPeter Maydell <peter.maydell@linaro.org>2025-02-24 11:15:17 +0000
committerPeter Maydell <peter.maydell@linaro.org>2025-02-25 15:32:57 +0000
commit44eb32a9835fe2feb19503e93476eee602daee0b (patch)
tree6615fb3fc6eef6579ccb25afed9df78d149620d0 /include/fpu/softfloat.h
parent9ea6d1f141426a7da91f1c7ba3d693472f0550a4 (diff)
downloadfocaccia-qemu-44eb32a9835fe2feb19503e93476eee602daee0b.tar.gz
focaccia-qemu-44eb32a9835fe2feb19503e93476eee602daee0b.zip
fpu: Make targets specify whether floatx80 Inf can have Int bit clear
In Intel terminology, a floatx80 Infinity with the explicit integer
bit clear is a "pseudo-infinity"; for x86 these are not valid
infinity values.  m68k is looser and does not care whether the
Integer bit is set or clear in an infinity.

Move this setting to runtime rather than using an ifdef in
floatx80_is_infinity().

Since this was the last use of the floatx80_infinity global constant,
we remove it and its definition here.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250224111524.1101196-6-peter.maydell@linaro.org
Message-id: 20250217125055.160887-5-peter.maydell@linaro.org
Diffstat (limited to 'include/fpu/softfloat.h')
-rw-r--r--include/fpu/softfloat.h18
1 files changed, 11 insertions, 7 deletions
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index 3c83d703ba..07259c5930 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -960,7 +960,6 @@ float128 floatx80_to_float128(floatx80, float_status *status);
 /*----------------------------------------------------------------------------
 | The pattern for an extended double-precision inf.
 *----------------------------------------------------------------------------*/
-extern const floatx80 floatx80_infinity;
 floatx80 floatx80_default_inf(bool zSign, float_status *status);
 
 /*----------------------------------------------------------------------------
@@ -998,12 +997,17 @@ static inline floatx80 floatx80_chs(floatx80 a)
 
 static inline bool floatx80_is_infinity(floatx80 a, float_status *status)
 {
-#if defined(TARGET_M68K)
-    return (a.high & 0x7fff) == floatx80_infinity.high && !(a.low << 1);
-#else
-    return (a.high & 0x7fff) == floatx80_infinity.high &&
-                       a.low == floatx80_infinity.low;
-#endif
+    /*
+     * It's target-specific whether the Integer bit is permitted
+     * to be 0 in a valid Infinity value. (x86 says no, m68k says yes).
+     */
+    bool intbit = a.low >> 63;
+
+    if (!intbit &&
+        !(status->floatx80_behaviour & floatx80_pseudo_inf_valid)) {
+        return false;
+    }
+    return (a.high & 0x7fff) == 0x7fff && !(a.low << 1);
 }
 
 static inline bool floatx80_is_neg(floatx80 a)