math: add double precision error handling functions

src/internal/libm.h

@@ -222,5 +222,10 @@ hidden float __math_uflowf(uint32_t);
 hidden float __math_oflowf(uint32_t);
 hidden float __math_divzerof(uint32_t);
 hidden float __math_invalidf(float);
+hidden double __math_xflow(uint32_t, double);
+hidden double __math_uflow(uint32_t);
+hidden double __math_oflow(uint32_t);
+hidden double __math_divzero(uint32_t);
+hidden double __math_invalid(double);
 
 #endif

src/math/__math_divzero.c

@@ -0,0 +1,6 @@
+#include "libm.h"
+
+double __math_divzero(uint32_t sign)
+{
+	return fp_barrier(sign ? -1.0 : 1.0) / 0.0;
+}

src/math/__math_invalid.c

@@ -0,0 +1,6 @@
+#include "libm.h"
+
+double __math_invalid(double x)
+{
+	return (x - x) / (x - x);
+}

src/math/__math_oflow.c

@@ -0,0 +1,6 @@
+#include "libm.h"
+
+double __math_oflow(uint32_t sign)
+{
+	return __math_xflow(sign, 0x1p769);
+}

src/math/__math_uflow.c

@@ -0,0 +1,6 @@
+#include "libm.h"
+
+double __math_uflow(uint32_t sign)
+{
+	return __math_xflow(sign, 0x1p-767);
+}

src/math/__math_xflow.c

@@ -0,0 +1,6 @@
+#include "libm.h"
+
+double __math_xflow(uint32_t sign, double y)
+{
+	return eval_as_double(fp_barrier(sign ? -y : y) * y);
+}