Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

gcc's version of inline assembly for the maths helpers #51

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

gcc's version of inline assembly for the maths helpers #51

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
120 changes: 116 additions & 4 deletions WaveSabreCore/src/Helpers.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,12 @@
#define _USE_MATH_DEFINES
#include <math.h>

#if (defined(_MSC_VER) && defined(_M_IX86)) || (defined(__GNUC__) && (defined(__x86_64__) || defined(__i386__)))
#define ASM_MATH_AVAILABLE (1)
#else
#define ASM_MATH_AVAILABLE (0)
#endif

#if defined(_MSC_VER) && defined(_M_IX86)
// TODO: make assembly equivalent for x64 (use intrinsic ?)
static __declspec(naked) double __vectorcall fpuExp2(double x)
Expand Down Expand Up @@ -34,7 +40,53 @@ static __declspec(naked) double __vectorcall fpuExp2(double x)
ret
}
}
#elif defined(__GNUC__)
#if defined(__x86_64__) || defined(__i386__)
__attribute__((__naked__,__noinline__)) static double fpuExp2(double x)
{
// i386 Linux ABI: pass thru the stack, return in st(0)
// x86_64 SysV ABI: pass/return thru xmm0/1
asm volatile(
#ifdef __x86_64__
"subq $8, %%rsp\n"
#else
"movsd 4(%%esp), %%xmm0\n"
"subl $8, %%esp\n"
#endif

#ifdef __x86_64__
"movsd %%xmm0, (%%rsp)\n"
"fldl (%%rsp)\n"
#else
"movsd %%xmm0, (%%esp)\n"
"fldl (%%esp)\n"
#endif

"fld %%st(0)\n"
"frndint\n"
"fsub %%st(0), %%st(1)\n"
"fxch %%st(1)\n"
"fchs\n"
"f2xm1\n"
"fld1\n"
"faddp %%st(0), %%st(1)\n"
"fscale\n"
"fstp %%st(1)\n"

#ifdef __x86_64__
"fstpl (%%rsp)\n"
"movsd (%%rsp), %%xmm0\n"
"addq $8, %%esp\n"
#else
"addl $8, %%esp\n"
#endif
"ret\n"
);
}
#endif // GCC arch
#endif // compiler

#if defined(_MSC_VER) && defined(_M_IX86)
static __declspec(naked) float __vectorcall fpuExp2F(float x)
{
__asm
Expand Down Expand Up @@ -63,7 +115,53 @@ static __declspec(naked) float __vectorcall fpuExp2F(float x)
ret
}
}
#elif defined(__GNUC__)
#if defined(__x86_64__) || defined(__i386__)
__attribute__((__naked__,__noinline__)) static float fpuExp2F(float x)
{
// i386 Linux ABI: pass thru the stack, return in st(0)
// x86_64 SysV ABI: pass/return thru xmm0/1
asm volatile(
#ifdef __x86_64__
"subq $8, %%rsp\n"
#else
"movss 4(%%esp), %%xmm0\n"
"subl $8, %%esp\n"
#endif

#ifdef __x86_64__
"movss %%xmm0, (%%rsp)\n"
"fldl (%%rsp)\n"
#else
"movss %%xmm0, (%%esp)\n"
"fldl (%%esp)\n"
#endif

"fld %%st(0)\n"
"frndint\n"
"fsub %%st(0), %%st(1)\n"
"fxch %%st(1)\n"
"fchs\n"
"f2xm1\n"
"fld1\n"
"faddp %%st(0), %%st(1)\n"
"fscale\n"
"fstp %%st(1)\n"

#ifdef __x86_64__
"fstpl (%%rsp)\n"
"movss (%%rsp), %%xmm0\n"
"addq $8, %%esp\n"
#else
"addl $8, %%esp\n"
#endif
PoroCYon marked this conversation as resolved.
Show resolved Hide resolved
"ret\n"
);
}
#endif // GCC arch
#endif // compiler

#if defined(_MSC_VER) && defined(_M_IX86)
static __declspec(naked) double __vectorcall fpuCos(double x)
{
__asm
Expand All @@ -81,7 +179,21 @@ static __declspec(naked) double __vectorcall fpuCos(double x)
ret
}
}
#endif // defined(_MSC_VER) && defined(_M_IX86)
#elif defined(__GNUC__)
#if defined(__x86_64__) || defined(__i386__)
__attribute__((__always_inline__)) inline static double fpuCos(double x)
{
// not writing the *entire* function body in assembly actually helps
// gcc and clang with inlining and LTO
// ... except trying this with fpuExp2/F somehow got botched, so those I
// wrote as pure assembly
asm volatile("fcos\n":"+t"(x)::);
return x;
}
#else
#define fpuCos(x) __builtin_cos(x)
#endif // GCC arch
#endif // compiler

namespace WaveSabreCore
{
Expand All @@ -100,7 +212,7 @@ namespace WaveSabreCore
for (int i = 0; i < fastCosTabSize + 1; i++)
{
double phase = double(i) * ((M_PI * 2) / fastCosTabSize);
#if defined(_MSC_VER) && defined(_M_IX86)
#if ASM_MATH_AVAILABLE
fastCosTab[i] = fpuCos(phase);
#else
fastCosTab[i] = cos(phase);
Expand All @@ -115,7 +227,7 @@ namespace WaveSabreCore

double Helpers::Exp2(double x)
{
#if defined(_MSC_VER) && defined(_M_IX86)
#if ASM_MATH_AVAILABLE
return fpuExp2(x);
#else
return pow(2.0, x);
Expand All @@ -124,7 +236,7 @@ namespace WaveSabreCore

float Helpers::Exp2F(float x)
{
#if defined(_MSC_VER) && defined(_M_IX86)
#if ASM_MATH_AVAILABLE
return fpuExp2F(x);
#else
return powf(2.0f, x);
Expand Down