From 4ee246ed0e02c61f0b33251d86ea74a4a0380a47 Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Thu, 10 Aug 2023 20:53:40 +0300
Subject: [PATCH] drc: fix reg alloc for div

libretro/pcsx_rearmed#745
---
 libpcsxcore/new_dynarec/new_dynarec.c | 30 +++++++++------------------
 1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/libpcsxcore/new_dynarec/new_dynarec.c b/libpcsxcore/new_dynarec/new_dynarec.c
index 37bdc3e7..d7c24365 100644
--- a/libpcsxcore/new_dynarec/new_dynarec.c
+++ b/libpcsxcore/new_dynarec/new_dynarec.c
@@ -2114,28 +2114,18 @@ static void multdiv_alloc(struct regstat *current,int i)
   clear_const(current,dops[i].rs2);
   alloc_cc(current,i); // for stalls
   dirty_reg(current,CCREG);
-  if(dops[i].rs1&&dops[i].rs2)
+  current->u &= ~(1ull << HIREG);
+  current->u &= ~(1ull << LOREG);
+  alloc_reg(current, i, HIREG);
+  alloc_reg(current, i, LOREG);
+  dirty_reg(current, HIREG);
+  dirty_reg(current, LOREG);
+  if ((dops[i].opcode2 & 0x3e) == 0x1a || (dops[i].rs1 && dops[i].rs2)) // div(u)
   {
-      current->u&=~(1LL<<HIREG);
-      current->u&=~(1LL<<LOREG);
-      alloc_reg(current,i,HIREG);
-      alloc_reg(current,i,LOREG);
-      alloc_reg(current,i,dops[i].rs1);
-      alloc_reg(current,i,dops[i].rs2);
-      dirty_reg(current,HIREG);
-      dirty_reg(current,LOREG);
-  }
-  else
-  {
-    // Multiply by zero is zero.
-    // MIPS does not have a divide by zero exception.
-    alloc_reg(current,i,HIREG);
-    alloc_reg(current,i,LOREG);
-    dirty_reg(current,HIREG);
-    dirty_reg(current,LOREG);
-    if (dops[i].rs1 && ((dops[i].opcode2 & 0x3e) == 0x1a)) // div(u) 0
-      alloc_reg(current, i, dops[i].rs1);
+    alloc_reg(current, i, dops[i].rs1);
+    alloc_reg(current, i, dops[i].rs2);
   }
+  // else multiply by zero is zero
 }
 #endif
 
-- 
2.39.2