Files
bmdhacks 3d15e04c6c Fix: VU sticky bits accumulate where the flags are produced, not at flush
VU_STAT_UPDATE assigned the bare ZSUO cause nibble to statusflag, throwing
the sticky field away, and _vuFMACflush re-derived the stickies from that
cause nibble on every pipeline entry it retired. That is idempotent right
up until an FSSET clears the sticky field: the stale cause then
regenerates the bit FSSET just cleared.

Traced on VUSTICKY_MICRO_FSSET_ASSIGNS_NOT_ORS. The FSSET merge itself is
correct -- it produces VI=801 -- and the bit comes back one entry later:

  [FSSET]      imm=800 sf 001 -> 801
  [FLUSH] pipe[2] flagreg=10000 entry.sf=801 VI=041 -> VI=801 (FSSET arm)
  [ADD]   pipe[3] lower VIwrite=8 snap.sf=801
  [FLUSH] pipe[3] flagreg=8     entry.sf=801 VI=801 -> VI=841 (FMAC arm)

pipe[3] is not an FMAC at all; flagreg=8 is a lower op writing integer
register VI[3]. It took the non-FSSET arm only because every retired entry
rewrites STATUS, and (sf & 0xF) << 6 turned the long-dead Z cause back
into sticky Z.

So the sticky OR moves to VU_STAT_UPDATE, where the flags are produced,
and both flush sites take the sticky field from the snapshot instead of
re-deriving it. statusflag is seeded from the whole STATUS register in
vu0ExecMicro, so carrying the sticky field in it is the documented intent
-- VU_STAT_UPDATE's original comment claimed exactly this preservation
while the code did the opposite.

Both halves are load-bearing: reverting VU_STAT_UPDATE alone fails the
Vu0AluUpper suite, reverting the flush arms alone leaves the FSSET rows
diverging.

Graduates VUSTICKY_MICRO_FSSET_CLEARS and
VUSTICKY_MICRO_FSSET_ASSIGNS_NOT_ORS from kMicroDivergences, which no
longer holds any interp-only row.

Idea by pstef.
2026-08-02 17:03:02 -07:00

109 lines
2.6 KiB
C++

// SPDX-FileCopyrightText: 2002-2026 PCSX2 Dev Team
// SPDX-License-Identifier: GPL-3.0+
#include "Common.h"
#include <cmath>
#include <float.h>
#include "VUmicro.h"
/*****************************************/
/* NEW FLAGS */ //By asadr. Thnkx F|RES :p
/*****************************************/
static __ri u32 VU_MAC_UPDATE( int shift, VURegs * VU, float f )
{
u32 v = *(u32*)&f;
int exp = (v >> 23) & 0xff;
u32 s = v & 0x80000000;
if (s)
VU->macflag |= 0x0010<<shift;
else
VU->macflag &= ~(0x0010<<shift);
if( f == 0 )
{
VU->macflag = (VU->macflag & ~(0x1100<<shift)) | (0x0001<<shift);
return v;
}
switch(exp)
{
case 0:
VU->macflag = (VU->macflag&~(0x1000<<shift)) | (0x0101<<shift);
return s;
case 255:
VU->macflag = (VU->macflag&~(0x0101<<shift)) | (0x1000<<shift);
if (CHECK_VU_OVERFLOW((VU == &VU1) ? 1 : 0))
return s | 0x7f7fffff; /* max allowed */
else
return v;
default:
VU->macflag = (VU->macflag & ~(0x1101<<shift));
return v;
}
}
__fi u32 VU_MACx_UPDATE(VURegs * VU, float x)
{
return VU_MAC_UPDATE(3, VU, x);
}
__fi u32 VU_MACy_UPDATE(VURegs * VU, float y)
{
return VU_MAC_UPDATE(2, VU, y);
}
__fi u32 VU_MACz_UPDATE(VURegs * VU, float z)
{
return VU_MAC_UPDATE(1, VU, z);
}
__fi u32 VU_MACw_UPDATE(VURegs * VU, float w)
{
return VU_MAC_UPDATE(0, VU, w);
}
__fi void VU_MACx_CLEAR(VURegs * VU)
{
VU->macflag&= ~(0x1111<<3);
}
__fi void VU_MACy_CLEAR(VURegs * VU)
{
VU->macflag&= ~(0x1111<<2);
}
__fi void VU_MACz_CLEAR(VURegs * VU)
{
VU->macflag&= ~(0x1111<<1);
}
__fi void VU_MACw_CLEAR(VURegs * VU)
{
VU->macflag&= ~(0x1111<<0);
}
__ri void VU_STAT_UPDATE(VURegs * VU) {
int newflag = 0 ;
if (VU->macflag & 0x000F) newflag = 0x1;
if (VU->macflag & 0x00F0) newflag |= 0x2;
if (VU->macflag & 0x0F00) newflag |= 0x4;
if (VU->macflag & 0xF000) newflag |= 0x8;
// Replace the ZSUO cause nibble and OR the matching sticky bits in, keeping
// the sticky field this op did not touch. The sticky OR has to happen HERE,
// at the point the flags are produced -- statusflag is seeded from the whole
// STATUS register (vu0ExecMicro), not from a bare cause nibble.
//
// Assigning `newflag` outright instead left the sticky field to be
// re-derived from the cause nibble by whoever consumed statusflag later.
// That is idempotent right up until an FSSET clears the sticky field, at
// which point the stale cause regenerates the bit FSSET just cleared.
//
// The D/I pair is deliberately not carried here: it belongs to the div unit,
// which maintains it in statusflag independently (VU_STICKY_DI).
VU->statusflag = (VU->statusflag & 0xFC0) | newflag | (newflag << 6);
}