Branchless Programming: Difference between revisions

← Older edit

@@ Line 43: / Line 43: @@
 </syntaxhighlight>
-==Multiplications==
+==Booleans==
+Multiplications by booleans can be used instead of switch statements.
 Rather than doing
-<pre>
+<syntaxhighlight lang="cpp">
-if age > 10:
+if (age > 10) {
-   x = x + 10
+   x += 10;
-else:
+} else {
-   x = x - 10
+   x -= 10;
-</pre>
+}
+</syntaxhighlight>
 you can do
-<pre>
+<syntaxhighlight lang="cpp">
-y = 2 * (age > 10) - 1
+x = x + (20 * (age > 10) - 10);
-x = x + 10 * y
 // or
-y = age > 10
+y = age > 10;
-x = x + 10 * y - 10 * (1-y)
+x = x + 10 * y - 10 * !y;
-</pre>
+</syntaxhighlight>
-These are micro optimizations but they are sometimes useful for speeding up GPU shaders.
+Similarly, instead of doing
+<syntaxhighlight lang="cpp">
+if (age > 10) {
+  x++;
+}
+</syntaxhighlight>
+you can just write <code>x += age>10;</code>.
+These are micro optimizations but they could be useful for speeding up GPU shaders in some cases.
+In high-level programming languages such as Python, these tricks can actually slow down your code<ref name="branchless-slower-python">https://stackoverflow.com/questions/72118249/why-are-the-branchless-and-built-in-functions-slower-in-python</ref>.
 ==Resources==
 * [https://francescocirillo.com/pages/anti-if-campaign Anti If Campaign]
+* [https://code.joejag.com/2016/anti-if-the-missing-patterns.html Anti-If: The missing patterns]
+==References==
+<references />