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pointless micro-optimizations #2127

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pointless micro-optimizations #2127

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e52b259
use bitshifts instead of mult for texture lookup
Jaklyy Apr 16, 2024
5b8bd44
very very minor optimization?
Jaklyy Aug 6, 2024
56638c8
Merge branch 'tex-lookup-optimze' into sdfgh
Jaklyy Aug 6, 2024
f6b73de
use bit manip instead of loops for ldm/stm
Jaklyy Aug 8, 2024
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143 changes: 66 additions & 77 deletions src/ARMInterpreter_LoadStore.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -400,11 +400,7 @@ void A_LDM(ARM* cpu)

if (!(cpu->CurInstr & (1<<23)))
{
for (int i = 0; i < 16; i++)
{
if (cpu->CurInstr & (1<<i))
base -= 4;
}
base -= 4 * __builtin_popcount(cpu->CurInstr & 0xFFFF);

if (cpu->CurInstr & (1<<21))
{
Expand All @@ -418,16 +414,17 @@ void A_LDM(ARM* cpu)
if ((cpu->CurInstr & (1<<22)) && !(cpu->CurInstr & (1<<15)))
cpu->UpdateMode(cpu->CPSR, (cpu->CPSR&~0x1F)|0x10, true);

for (int i = 0; i < 15; i++)
u16 reglist = cpu->CurInstr & 0x7FFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (preinc) base += 4;
if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
if (!preinc) base += 4;
}
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (preinc) base += 4;
if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
if (!preinc) base += 4;
}

if (cpu->CurInstr & (1<<15))
Expand Down Expand Up @@ -479,11 +476,7 @@ void A_STM(ARM* cpu)

if (!(cpu->CurInstr & (1<<23)))
{
for (u32 i = 0; i < 16; i++)
{
if (cpu->CurInstr & (1<<i))
base -= 4;
}
base -= 4 * __builtin_popcount(cpu->CurInstr & 0xFFFF);

if (cpu->CurInstr & (1<<21))
cpu->R[baseid] = base;
Expand All @@ -503,26 +496,27 @@ void A_STM(ARM* cpu)
cpu->UpdateMode(cpu->CPSR, (cpu->CPSR&~0x1F)|0x10, true);
}

for (u32 i = 0; i < 16; i++)
u16 reglist = cpu->CurInstr & 0xFFFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (preinc) base += 4;
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (i == baseid && !isbanked)
{
if ((cpu->Num == 0) || (!(cpu->CurInstr & ((1<<i)-1))))
first ? cpu->DataWrite32(base, oldbase) : cpu->DataWrite32S(base, oldbase);
else
first ? cpu->DataWrite32(base, base) : cpu->DataWrite32S(base, base); // checkme
}
if (preinc) base += 4;

if (i == baseid && !isbanked)
{
if ((cpu->Num == 0) || (!(cpu->CurInstr & ((1<<i)-1))))
first ? cpu->DataWrite32(base, oldbase) : cpu->DataWrite32S(base, oldbase);
else
first ? cpu->DataWrite32(base, cpu->R[i]) : cpu->DataWrite32S(base, cpu->R[i]);
first ? cpu->DataWrite32(base, base) : cpu->DataWrite32S(base, base); // checkme
}
else
first ? cpu->DataWrite32(base, cpu->R[i]) : cpu->DataWrite32S(base, cpu->R[i]);

first = false;
first = false;

if (!preinc) base += 4;
}
if (!preinc) base += 4;
}

if (cpu->CurInstr & (1<<22))
Expand Down Expand Up @@ -700,31 +694,23 @@ void T_LDR_SPREL(ARM* cpu)

void T_PUSH(ARM* cpu)
{
int nregs = 0;
bool first = true;

for (int i = 0; i < 8; i++)
{
if (cpu->CurInstr & (1<<i))
nregs++;
}

if (cpu->CurInstr & (1<<8))
nregs++;

u32 base = cpu->R[13];
base -= (nregs<<2);
base -= 4 * __builtin_popcount(cpu->CurInstr & 0x1FF);

cpu->R[13] = base;

for (int i = 0; i < 8; i++)
u8 reglist = cpu->CurInstr & 0xFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (first) cpu->DataWrite32 (base, cpu->R[i]);
else cpu->DataWrite32S(base, cpu->R[i]);
first = false;
base += 4;
}
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (first) cpu->DataWrite32 (base, cpu->R[i]);
else cpu->DataWrite32S(base, cpu->R[i]);
first = false;
base += 4;
}

if (cpu->CurInstr & (1<<8))
Expand All @@ -741,15 +727,16 @@ void T_POP(ARM* cpu)
u32 base = cpu->R[13];
bool first = true;

for (int i = 0; i < 8; i++)
u8 reglist = cpu->CurInstr & 0xFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
base += 4;
}
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
base += 4;
}

if (cpu->CurInstr & (1<<8))
Expand All @@ -771,15 +758,16 @@ void T_STMIA(ARM* cpu)
u32 base = cpu->R[(cpu->CurInstr >> 8) & 0x7];
bool first = true;

for (int i = 0; i < 8; i++)
u8 reglist = cpu->CurInstr & 0xFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (first) cpu->DataWrite32 (base, cpu->R[i]);
else cpu->DataWrite32S(base, cpu->R[i]);
first = false;
base += 4;
}
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (first) cpu->DataWrite32 (base, cpu->R[i]);
else cpu->DataWrite32S(base, cpu->R[i]);
first = false;
base += 4;
}

// TODO: check "Rb included in Rlist" case
Expand All @@ -792,15 +780,16 @@ void T_LDMIA(ARM* cpu)
u32 base = cpu->R[(cpu->CurInstr >> 8) & 0x7];
bool first = true;

for (int i = 0; i < 8; i++)
u8 reglist = cpu->CurInstr & 0xFF;
while (reglist)
{
if (cpu->CurInstr & (1<<i))
{
if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
base += 4;
}
int i = __builtin_ctz(reglist);
reglist ^= 1<<i;

if (first) cpu->DataRead32 (base, &cpu->R[i]);
else cpu->DataRead32S(base, &cpu->R[i]);
first = false;
base += 4;
}

if (!(cpu->CurInstr & (1<<((cpu->CurInstr >> 8) & 0x7))))
Expand Down
16 changes: 9 additions & 7 deletions src/GPU3D_Soft.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -143,6 +143,8 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s
u32 vramaddr = (texparam & 0xFFFF) << 3;

s32 width = 8 << ((texparam >> 20) & 0x7);
// since width is always a multple of 8 (thus a multiple of 2) we can replace all multiplications by width with a bitshift
s32 widthshift = 3 + ((texparam >> 20) & 0x7);
s32 height = 8 << ((texparam >> 23) & 0x7);

s >>= 4;
Expand Down Expand Up @@ -192,7 +194,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s
{
case 1: // A3I5
{
vramaddr += ((t * width) + s);
vramaddr += ((t << widthshift) + s);
u8 pixel = ReadVRAM_Texture<u8>(vramaddr, gpu);

texpal <<= 4;
Expand All @@ -203,7 +205,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 2: // 4-color
{
vramaddr += (((t * width) + s) >> 2);
vramaddr += (((t << widthshift) + s) >> 2);
u8 pixel = ReadVRAM_Texture<u8>(vramaddr, gpu);
pixel >>= ((s & 0x3) << 1);
pixel &= 0x3;
Expand All @@ -216,7 +218,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 3: // 16-color
{
vramaddr += (((t * width) + s) >> 1);
vramaddr += (((t << widthshift) + s) >> 1);
u8 pixel = ReadVRAM_Texture<u8>(vramaddr, gpu);
if (s & 0x1) pixel >>= 4;
else pixel &= 0xF;
Expand All @@ -229,7 +231,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 4: // 256-color
{
vramaddr += ((t * width) + s);
vramaddr += ((t << widthshift) + s);
u8 pixel = ReadVRAM_Texture<u8>(vramaddr, gpu);

texpal <<= 4;
Expand All @@ -240,7 +242,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 5: // compressed
{
vramaddr += ((t & 0x3FC) * (width>>2)) + (s & 0x3FC);
vramaddr += ((t & 0x3FC) << (widthshift-2)) + (s & 0x3FC);
vramaddr += (t & 0x3);
vramaddr &= 0x7FFFF; // address used for all calcs wraps around after slot 3

Expand Down Expand Up @@ -352,7 +354,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 6: // A5I3
{
vramaddr += ((t * width) + s);
vramaddr += ((t << widthshift) + s);
u8 pixel = ReadVRAM_Texture<u8>(vramaddr, gpu);

texpal <<= 4;
Expand All @@ -363,7 +365,7 @@ void SoftRenderer::TextureLookup(const GPU& gpu, u32 texparam, u32 texpal, s16 s

case 7: // direct color
{
vramaddr += (((t * width) + s) << 1);
vramaddr += (((t << widthshift) + s) << 1);
*color = ReadVRAM_Texture<u16>(vramaddr, gpu);
*alpha = (*color & 0x8000) ? 31 : 0;
}
Expand Down
14 changes: 7 additions & 7 deletions src/GPU3D_Soft.h
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Original file line number Diff line number Diff line change
Expand Up @@ -101,15 +101,15 @@

if ((w0 & 0x1) && !(w1 & 0x1))
{
this->w0n = w0 - 1;
this->w0d = w0 + 1;
this->w1d = w1;
this->w0n = w0 - 1 >> 1;

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '-'; '-' will be evaluated first [-Wshift-op-parentheses]
this->w0d = w0 + 1 >> 1;

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]

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operator '>>' has lower precedence than '+'; '+' will be evaluated first [-Wshift-op-parentheses]
this->w1d = w1 >> 1;
}
else
{
this->w0n = w0 & 0xFFFE;
this->w0d = w0 & 0xFFFE;
this->w1d = w1 & 0xFFFE;
this->w0n = w0 >> 1;
this->w0d = w0 >> 1;
this->w1d = w1 >> 1;
}

this->shift = 9;
Expand Down Expand Up @@ -138,7 +138,7 @@
// this seems to be a proper division on hardware :/
// I haven't been able to find cases that produce imperfect output
if (den == 0) yfactor = 0;
else yfactor = (s32)(num / den);
else yfactor = ((u32)num / den);
}
}

Expand Down
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