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llvmpipe: add sse code for fixed position calculation 

This is quite a few less instructions, albeit still do the 2 64bit muls
with scalar c code (they'd need way more shuffles, plus fixup for the signed
mul so it totally doesn't seem worth it - x86 can do 32x32->64bit signed
scalar muls natively just fine after all (even on 32bit).

(This still doesn't have a very measurable performance impact in reality,
although profiler seems to say time spent in setup indeed has gone down by
10% or so overall. Maybe good for a 3% or so improvement in openarena.)

Reviewed-by: Brian Paul <brianp@vmware.com>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
This commit is contained in:
Roland Scheidegger 2016-01-02 04:59:16 +01:00
parent 9422999e40
commit 0298f5aca7
1 changed files with 50 additions and 8 deletions
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58
src/gallium/drivers/llvmpipe/lp_setup_tri.c
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@ -68,11 +68,11 @@ fixed_to_float(int a)
struct fixed_position {
int32_t x[4];
int32_t y[4];
int64_t area;
int32_t dx01;
int32_t dy01;
int32_t dx20;
int32_t dy20;
int64_t area;
};
@ -966,29 +966,71 @@ static void retry_triangle_ccw( struct lp_setup_context *setup,
/**
* Calculate fixed position data for a triangle
* It is unfortunate we need to do that here (as we need area
* calculated in fixed point), as there's quite some code duplication
* to what is done in the jit setup prog.
*/
static inline void
calc_fixed_position( struct lp_setup_context *setup,
struct fixed_position* position,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4])
calc_fixed_position(struct lp_setup_context *setup,
struct fixed_position* position,
const float (*v0)[4],
const float (*v1)[4],
const float (*v2)[4])
{
/*
* The rounding may not be quite the same with PIPE_ARCH_SSE
* (util_iround right now only does nearest/even on x87,
* otherwise nearest/away-from-zero).
* Both should be acceptable, I think.
*/
#if defined(PIPE_ARCH_SSE)
__m128d v0r, v1r, v2r;
__m128 vxy0xy2, vxy1xy0;
__m128i vxy0xy2i, vxy1xy0i;
__m128i dxdy0120, x0x2y0y2, x1x0y1y0, x0120, y0120;
__m128 pix_offset = _mm_set1_ps(setup->pixel_offset);
__m128 fixed_one = _mm_set1_ps((float)FIXED_ONE);
v0r = _mm_load_sd((const double *)v0[0]);
v1r = _mm_load_sd((const double *)v1[0]);
v2r = _mm_load_sd((const double *)v2[0]);
vxy0xy2 = (__m128)_mm_unpacklo_pd(v0r, v2r);
vxy1xy0 = (__m128)_mm_unpacklo_pd(v1r, v0r);
vxy0xy2 = _mm_sub_ps(vxy0xy2, pix_offset);
vxy1xy0 = _mm_sub_ps(vxy1xy0, pix_offset);
vxy0xy2 = _mm_mul_ps(vxy0xy2, fixed_one);
vxy1xy0 = _mm_mul_ps(vxy1xy0, fixed_one);
vxy0xy2i = _mm_cvtps_epi32(vxy0xy2);
vxy1xy0i = _mm_cvtps_epi32(vxy1xy0);
dxdy0120 = _mm_sub_epi32(vxy0xy2i, vxy1xy0i);
_mm_store_si128((__m128i *)&position->dx01, dxdy0120);
/*
* For the mul, would need some more shuffles, plus emulation
* for the signed mul (without sse41), so don't bother.
*/
x0x2y0y2 = _mm_shuffle_epi32(vxy0xy2i, _MM_SHUFFLE(3,1,2,0));
x1x0y1y0 = _mm_shuffle_epi32(vxy1xy0i, _MM_SHUFFLE(3,1,2,0));
x0120 = _mm_unpacklo_epi32(x0x2y0y2, x1x0y1y0);
y0120 = _mm_unpackhi_epi32(x0x2y0y2, x1x0y1y0);
_mm_store_si128((__m128i *)&position->x[0], x0120);
_mm_store_si128((__m128i *)&position->y[0], y0120);
#else
position->x[0] = subpixel_snap(v0[0][0] - setup->pixel_offset);
position->x[1] = subpixel_snap(v1[0][0] - setup->pixel_offset);
position->x[2] = subpixel_snap(v2[0][0] - setup->pixel_offset);
position->x[3] = 0;
position->x[3] = 0; // should be unused
position->y[0] = subpixel_snap(v0[0][1] - setup->pixel_offset);
position->y[1] = subpixel_snap(v1[0][1] - setup->pixel_offset);
position->y[2] = subpixel_snap(v2[0][1] - setup->pixel_offset);
position->y[3] = 0;
position->y[3] = 0; // should be unused
position->dx01 = position->x[0] - position->x[1];
position->dy01 = position->y[0] - position->y[1];
position->dx20 = position->x[2] - position->x[0];
position->dy20 = position->y[2] - position->y[0];
#endif
position->area = IMUL64(position->dx01, position->dy20) -
IMUL64(position->dx20, position->dy01);