powerpc: Add optimized ilogb* for POWER9

The instructions xsxexpdp and xsxexpqp introduced on POWER9 extract
the exponent from a double-precision and quad-precision floating-point
respectively, thus they can be used to improve ilogb, ilogbf and ilogbf128.

2 files changed, 34 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/le/fpu/w_ilogb_template.c b/sysdeps/powerpc/powerpc64/le/fpu/w_ilogb_template.c
new file mode 100644
index 0000000000..b5c1c0aa9d
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/fpu/w_ilogb_template.c
@@ -0,0 +1,30 @@
+#include <math.h>
+#include <errno.h>
+#include <limits.h>
+#include <math_private.h>
+#include <fenv.h>
+
+#if _GL_HAS_BUILTIN_ILOGB
+int
+M_DECL_FUNC (__ilogb) (FLOAT x)
+{
+  int r;
+  /* Check for exceptional cases.  */
+  if (! M_SUF(__builtin_test_dc_ilogb) (x, 0x7f))
+    r = M_SUF (__builtin_ilogb) (x);
+  else
+    /* Fallback to the generic ilogb if x is NaN, Inf or subnormal.  */
+    r = M_SUF (__ieee754_ilogb) (x);
+  if (__builtin_expect (r == FP_ILOGB0, 0)
+      || __builtin_expect (r == FP_ILOGBNAN, 0)
+      || __builtin_expect (r == INT_MAX, 0))
+    {
+      __set_errno (EDOM);
+      __feraiseexcept (FE_INVALID);
+    }
+  return r;
+}
+declare_mgen_alias (__ilogb, ilogb)
+#else
+#include <math/w_ilogb_template.c>
+#endif
diff --git a/sysdeps/powerpc/powerpc64/le/fpu/w_ilogbl.c b/sysdeps/powerpc/powerpc64/le/fpu/w_ilogbl.c
new file mode 100644
index 0000000000..205f154f00
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/fpu/w_ilogbl.c
@@ -0,0 +1,4 @@
+/* Skip the optimization for long double as ibm128 does not provide an
+   optimized builtin. */
+#include <math-type-macros-ldouble.h>
+#include <math/w_ilogb_template.c>