From 3034f5d2c49d80c9a054a6520225a9c27da37d7e Mon Sep 17 00:00:00 2001
From: Fabian Greffrath <fabian@greffrath.com>
Date: Mon, 3 Mar 2025 06:59:09 +0100
Subject: [PATCH 1/2] declare lo and hi in div64_32() as volatile

Fixes #2219
---
 src/m_fixed.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/m_fixed.h b/src/m_fixed.h
index bb6f24815..7859e3e2b 100644
--- a/src/m_fixed.h
+++ b/src/m_fixed.h
@@ -38,8 +38,8 @@
       {
           return a / b;
       }
-      int32_t lo = a;
-      int32_t hi = a >> 32;
+      volatile int32_t lo = a;
+      volatile int32_t hi = a >> 32;
       asm("idivl %[divisor]" : "+a" (lo), "+d" (hi) : [divisor] "r" (b));
       return lo;
   }

From 1b0b2f759916e6d73f66fa4a93833f017df7f288 Mon Sep 17 00:00:00 2001
From: Fabian Greffrath <fabian@greffrath.com>
Date: Tue, 4 Mar 2025 10:02:57 +0100
Subject: [PATCH 2/2] remove ASM div64_32() implementation

* Prone to miscompilation
* Only helps with very old PCs
* Really only helps with voxel rendering
---
 src/m_fixed.h | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/src/m_fixed.h b/src/m_fixed.h
index 7859e3e2b..86a0468c0 100644
--- a/src/m_fixed.h
+++ b/src/m_fixed.h
@@ -30,20 +30,6 @@
 
   #define div64_32(a, b) _div64((a), (b), NULL)
 
-#elif defined(__GNUC__) && defined(__x86_64__)
-
-  inline static int32_t div64_32(int64_t a, int32_t b)
-  {
-      if (__builtin_constant_p(b))
-      {
-          return a / b;
-      }
-      volatile int32_t lo = a;
-      volatile int32_t hi = a >> 32;
-      asm("idivl %[divisor]" : "+a" (lo), "+d" (hi) : [divisor] "r" (b));
-      return lo;
-  }
-
 #else
 
   #define div64_32(a, b) ((fixed_t)((a) / (b)))