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Optimize SkVM selects.

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The expression `!x ? y : z` can be optimized to `x ? z : y`, saving a
bit-not. SkVM now supports this optimization.

Change-Id: I06a0d2a716947de1021ba66b054b92e25568c641
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/524226
Reviewed-by: Arman Uguray <armansito@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
This commit is contained in:
John Stiles 2022-03-24 16:35:32 -04:00 committed by SkCQ
parent 059d34594e
commit ae5984082b
2 changed files with 25 additions and 23 deletions
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12
src/core/SkVM.cpp
View File

@ -1163,10 +1163,14 @@ namespace skvm {
I32 Builder::select(I32 x, I32 y, I32 z) {
if (y.id == z.id) { return y; }
if (int X,Y,Z; this->allImm(x.id,&X, y.id,&Y, z.id,&Z)) { return splat(X?Y:Z); }
if (this->isImm(x.id,~0)) { return y; } // true ? y : z == y
if (this->isImm(x.id, 0)) { return z; } // false ? y : z == z
if (this->isImm(y.id, 0)) { return bit_clear(z,x); } // x ? 0 : z == ~x&z
if (this->isImm(z.id, 0)) { return bit_and (y,x); } // x ? y : 0 == x&y
if (this->isImm(x.id,~0)) { return y; } // (true ? y : z) == y
if (this->isImm(x.id, 0)) { return z; } // (false ? y : z) == z
if (this->isImm(y.id, 0)) { return bit_clear(z,x); } // (x ? 0 : z) == ~x&z
if (this->isImm(z.id, 0)) { return bit_and (y,x); } // (x ? y : 0) == x&y
if (Val notX = this->holdsBitNot(x.id); notX != NA) { // (!x ? y : z) == (x ? z : y)
x.id = notX;
std::swap(y, z);
}
return {this, this->push(Op::select, x.id, y.id, z.id)};
}

36
tests/sksl/runtime/ConversionConstructors.skvm
View File

@ -1,24 +1,22 @@
8 registers, 22 instructions:
7 registers, 20 instructions:
0 r0 = uniform32 ptr0 4
1 r1 = uniform32 ptr0 8
2 r2 = uniform32 ptr0 C
3 r3 = splat 0 (0)
4 r4 = splat FFFFFFFF (nan)
5 r5 = neq_f32 r0 r3
6 r6 = splat 3F800000 (1)
7 r6 = bit_and r2 r6
8 r7 = to_f32 r1
9 r7 = select r5 r6 r7
10 r3 = eq_i32 r1 r3
11 r4 = bit_xor r3 r4
12 r3 = splat 1 (1.4012985e-45)
13 r3 = bit_and r2 r3
14 r0 = trunc r0
15 r0 = select r4 r3 r0
16 r0 = to_f32 r0
17 r0 = mul_f32 r7 r0
4 r4 = neq_f32 r0 r3
5 r5 = splat 3F800000 (1)
6 r5 = bit_and r2 r5
7 r6 = to_f32 r1
8 r6 = select r4 r5 r6
9 r3 = eq_i32 r1 r3
10 r1 = splat 1 (1.4012985e-45)
11 r1 = bit_and r2 r1
12 r0 = trunc r0
13 r1 = select r3 r0 r1
14 r1 = to_f32 r1
15 r1 = mul_f32 r6 r1
loop:
18 store32 ptr1 r0
19 store32 ptr2 r0
20 store32 ptr3 r0
21 store32 ptr4 r0
16 store32 ptr1 r1
17 store32 ptr2 r1
18 store32 ptr3 r1
19 store32 ptr4 r1