commit 9ef6ca4235b7a66aefa432295c02b4df64a53f2e
author Szabolcs Nagy <nsz@port70.net> Sun Oct 22 13:51:35 2017 +0000
committer Rich Felker <dalias@aerifal.cx> Wed Apr 17 13:08:42 2019 -0400
tree 21c1f5ef1a000735d15242cf4e0c4bde50b56ae7
parent fe54544f055959bb7406758881d0fb85920b3f0e

math: add single precision error handling functions

These are supposed to be used in tail call positions when handling
special cases in new code. (fp exceptions may be raised "naturally"
by the common code path if special casing is more effort.)

This implements the error handling apis used in
https://github.com/ARM-software/optimized-routines
without errno setting.

src/internal/libm.h

diff --git a/src/internal/libm.h b/src/internal/libm.h
index 09fcfde..a52a0b8 100644
--- a/src/internal/libm.h
+++ b/src/internal/libm.h
@@ -216,4 +216,11 @@
 hidden double __lgamma_r(double, int *);
 hidden float __lgammaf_r(float, int *);
 
+/* error handling functions */
+hidden float __math_xflowf(uint32_t, float);
+hidden float __math_uflowf(uint32_t);
+hidden float __math_oflowf(uint32_t);
+hidden float __math_divzerof(uint32_t);
+hidden float __math_invalidf(float);
+
 #endif

src/math/__math_divzerof.c

diff --git a/src/math/__math_divzerof.c b/src/math/__math_divzerof.c
new file mode 100644
index 0000000..ce046f3
--- /dev/null
+++ b/src/math/__math_divzerof.c
@@ -0,0 +1,6 @@
+#include "libm.h"
+
+float __math_divzerof(uint32_t sign)
+{
+	return fp_barrierf(sign ? -1.0f : 1.0f) / 0.0f;
+}

src/math/__math_invalidf.c

diff --git a/src/math/__math_invalidf.c b/src/math/__math_invalidf.c
new file mode 100644
index 0000000..357d4b1
--- /dev/null
+++ b/src/math/__math_invalidf.c
@@ -0,0 +1,6 @@
+#include "libm.h"
+
+float __math_invalidf(float x)
+{
+	return (x - x) / (x - x);
+}

src/math/__math_oflowf.c

diff --git a/src/math/__math_oflowf.c b/src/math/__math_oflowf.c
new file mode 100644
index 0000000..fa7d062
--- /dev/null
+++ b/src/math/__math_oflowf.c
@@ -0,0 +1,6 @@
+#include "libm.h"
+
+float __math_oflowf(uint32_t sign)
+{
+	return __math_xflowf(sign, 0x1p97f);
+}

src/math/__math_uflowf.c

diff --git a/src/math/__math_uflowf.c b/src/math/__math_uflowf.c
new file mode 100644
index 0000000..94d50f2
--- /dev/null
+++ b/src/math/__math_uflowf.c
@@ -0,0 +1,6 @@
+#include "libm.h"
+
+float __math_uflowf(uint32_t sign)
+{
+	return __math_xflowf(sign, 0x1p-95f);
+}

src/math/__math_xflowf.c

diff --git a/src/math/__math_xflowf.c b/src/math/__math_xflowf.c
new file mode 100644
index 0000000..f2c8478
--- /dev/null
+++ b/src/math/__math_xflowf.c
@@ -0,0 +1,6 @@
+#include "libm.h"
+
+float __math_xflowf(uint32_t sign, float y)
+{
+	return eval_as_float(fp_barrierf(sign ? -y : y) * y);
+}