glsl: Add isinf() and isnan() builtins.

The implementations are as follows:

isinf(x) = (abs(x) == +infinity)
isnan(x) = (x != x)

Note: the latter formula is not necessarily obvious.  It works because
NaN is the only floating point number that does not equal itself.

Fixes piglit tests "isinf-and-isnan fs_basic" and "isinf-and-isnan
vs_basic".

1 files changed, 17 insertions, 0 deletions

diff --git a/src/glsl/builtins/ir/isnan.ir b/src/glsl/builtins/ir/isnan.ir
new file mode 100644
index 00000000000..b67349f2a5c
--- /dev/null
+++ b/src/glsl/builtins/ir/isnan.ir
@@ -0,0 +1,17 @@
+((function isnan
+   (signature bool
+     (parameters
+       (declare (in) float x))
+     ((return (expression bool != (var_ref x) (var_ref x)))))
+   (signature bvec2
+     (parameters
+       (declare (in) vec2 x))
+     ((return (expression bvec2 != (var_ref x) (var_ref x)))))
+   (signature bvec3
+     (parameters
+       (declare (in) vec3 x))
+     ((return (expression bvec3 != (var_ref x) (var_ref x)))))
+   (signature bvec4
+     (parameters
+       (declare (in) vec4 x))
+     ((return (expression bvec4 != (var_ref x) (var_ref x)))))))