From d2eb71e398e4cc8e794fd7904bd4e186498078ad Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <raymond.hettinger@gmail.com>
Date: Sun, 26 Aug 2018 14:04:00 -0700
Subject: [PATCH 1/2] Add fast path for exact floats.

Saves function call overhead and lets inner-loop be performed
in registers with no spills/reloads.
---
 Modules/mathmodule.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 2d483afff54d1b..1082c44860fda5 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -2183,9 +2183,13 @@ math_hypot(PyObject *self, PyObject *args)
     }
     for (i=0 ; i<n ; i++) {
         item = PyTuple_GET_ITEM(args, i);
-        x = PyFloat_AsDouble(item);
-        if (x == -1.0 && PyErr_Occurred()) {
-            goto error_exit;
+        if (PyFloat_CheckExact(item)) {
+            x = PyFloat_AS_DOUBLE(item);
+        } else {
+            x = PyFloat_AsDouble(item);
+            if (x == -1.0 && PyErr_Occurred()) {
+                goto error_exit;
+            }
         }
         x = fabs(x);
         coordinates[i] = x;

From f1cffbc73d69e3b1f6bc26051b964d133233a970 Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <raymond.hettinger@gmail.com>
Date: Sun, 26 Aug 2018 16:27:35 -0700
Subject: [PATCH 2/2] Extend the exact float fastpath to math_dist().

---
 Modules/mathmodule.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/Modules/mathmodule.c b/Modules/mathmodule.c
index 1082c44860fda5..62d327998fd183 100644
--- a/Modules/mathmodule.c
+++ b/Modules/mathmodule.c
@@ -2134,14 +2134,22 @@ math_dist_impl(PyObject *module, PyObject *p, PyObject *q)
     }
     for (i=0 ; i<n ; i++) {
         item = PyTuple_GET_ITEM(p, i);
-        px = PyFloat_AsDouble(item);
-        if (px == -1.0 && PyErr_Occurred()) {
-            goto error_exit;
+        if (PyFloat_CheckExact(item)) {
+            px = PyFloat_AS_DOUBLE(item);
+        } else {
+            px = PyFloat_AsDouble(item);
+            if (px == -1.0 && PyErr_Occurred()) {
+                goto error_exit;
+            }
         }
         item = PyTuple_GET_ITEM(q, i);
-        qx = PyFloat_AsDouble(item);
-        if (qx == -1.0 && PyErr_Occurred()) {
-            goto error_exit;
+        if (PyFloat_CheckExact(item)) {
+            qx = PyFloat_AS_DOUBLE(item);
+        } else {
+            qx = PyFloat_AsDouble(item);
+            if (qx == -1.0 && PyErr_Occurred()) {
+                goto error_exit;
+            }
         }
         x = fabs(px - qx);
         diffs[i] = x;