From b6772ac2ea6b635129803566e576c050c38ea576 Mon Sep 17 00:00:00 2001
From: "Justin C. Miller" <justin@devjustinian.com>
Date: Wed, 17 Feb 2021 00:22:22 -0800
Subject: [PATCH] [kernel] Fix #DF when building with -O3

I had failed to specify in inline asm that an input variable was the
same as the output variable.
---
 src/kernel/frame_allocator.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/kernel/frame_allocator.cpp b/src/kernel/frame_allocator.cpp
index 169859f..327a47b 100644
--- a/src/kernel/frame_allocator.cpp
+++ b/src/kernel/frame_allocator.cpp
@@ -25,7 +25,7 @@ frame_allocator::frame_allocator(kernel::args::frame_block *frames, size_t count
 inline unsigned
 bsf(uint64_t v)
 {
-	asm ("tzcntq %q0, %q1" : "=r"(v) : "r"(v) : "cc");
+	asm ("tzcntq %q0, %q1" : "=r"(v) : "0"(v) : "cc");
 	return v;
 }