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tgsi/lowering: improved lowering for LRP

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Provide an improved lowering for LRP, which can be implemented in two
MAD instructions with a bit of rearranging of the equation, rather
than the literal implementation of two multiplies, an add and a
subtract.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robclark@freedesktop.org>
This commit is contained in:
Russell King 2016-04-13 18:42:42 -04:00 • committed by Rob Clark
parent 67da7dd98a
commit fadfaa82c6
1 changed files with 20 additions and 35 deletions
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55
src/gallium/auxiliary/tgsi/tgsi_lowering.c
View file

@ -388,14 +388,15 @@ transform_scs(struct tgsi_transform_context *tctx,
* dst.z = src0.z \times src1.z + (1.0 - src0.z) \times src2.z
* dst.w = src0.w \times src1.w + (1.0 - src0.w) \times src2.w
*
* ; needs: 2 tmp, imm{1.0}
* MUL tmpA, src0, src1
* SUB tmpB, imm{1.0}, src0
* MUL tmpB, tmpB, src2
* ADD dst, tmpA, tmpB
* This becomes: src0 \times src1 + src2 - src0 \times src2, which
* can then become: src0 \times src1 - (src0 \times src2 - src2)
*
* ; needs: 1 tmp
* MAD tmpA, src0, src2, -src2
* MAD dst, src0, src1, -tmpA
*/
#define LRP_GROW (NINST(2) + NINST(2) + NINST(2) + NINST(2) - OINST(3))
#define LRP_TMP 2
#define LRP_GROW (NINST(3) + NINST(3) - OINST(3))
#define LRP_TMP 1
static void
transform_lrp(struct tgsi_transform_context *tctx,
struct tgsi_full_instruction *inst)
@ -408,44 +409,28 @@ transform_lrp(struct tgsi_transform_context *tctx,
struct tgsi_full_instruction new_inst;
if (dst->Register.WriteMask & TGSI_WRITEMASK_XYZW) {
/* MUL tmpA, src0, src1 */
/* MAD tmpA, src0, src2, -src2 */
new_inst = tgsi_default_full_instruction();
new_inst.Instruction.Opcode = TGSI_OPCODE_MUL;
new_inst.Instruction.Opcode = TGSI_OPCODE_MAD;
new_inst.Instruction.NumDstRegs = 1;
reg_dst(&new_inst.Dst[0], &ctx->tmp[A].dst, TGSI_WRITEMASK_XYZW);
new_inst.Instruction.NumSrcRegs = 2;
new_inst.Instruction.NumSrcRegs = 3;
reg_src(&new_inst.Src[0], src0, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[1], src1, SWIZ(X, Y, Z, W));
tctx->emit_instruction(tctx, &new_inst);
/* SUB tmpB, imm{1.0}, src0 */
new_inst = tgsi_default_full_instruction();
new_inst.Instruction.Opcode = TGSI_OPCODE_SUB;
new_inst.Instruction.NumDstRegs = 1;
reg_dst(&new_inst.Dst[0], &ctx->tmp[B].dst, TGSI_WRITEMASK_XYZW);
new_inst.Instruction.NumSrcRegs = 2;
reg_src(&new_inst.Src[0], &ctx->imm, SWIZ(Y, Y, Y, Y));
reg_src(&new_inst.Src[1], src0, SWIZ(X, Y, Z, W));
tctx->emit_instruction(tctx, &new_inst);
/* MUL tmpB, tmpB, src2 */
new_inst = tgsi_default_full_instruction();
new_inst.Instruction.Opcode = TGSI_OPCODE_MUL;
new_inst.Instruction.NumDstRegs = 1;
reg_dst(&new_inst.Dst[0], &ctx->tmp[B].dst, TGSI_WRITEMASK_XYZW);
new_inst.Instruction.NumSrcRegs = 2;
reg_src(&new_inst.Src[0], &ctx->tmp[B].src, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[1], src2, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[2], src2, SWIZ(X, Y, Z, W));
new_inst.Src[2].Register.Negate = !new_inst.Src[2].Register.Negate;
tctx->emit_instruction(tctx, &new_inst);
/* ADD dst, tmpA, tmpB */
/* MAD dst, src0, src1, -tmpA */
new_inst = tgsi_default_full_instruction();
new_inst.Instruction.Opcode = TGSI_OPCODE_ADD;
new_inst.Instruction.Opcode = TGSI_OPCODE_MAD;
new_inst.Instruction.NumDstRegs = 1;
reg_dst(&new_inst.Dst[0], dst, TGSI_WRITEMASK_XYZW);
new_inst.Instruction.NumSrcRegs = 2;
reg_src(&new_inst.Src[0], &ctx->tmp[A].src, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[1], &ctx->tmp[B].src, SWIZ(X, Y, Z, W));
new_inst.Instruction.NumSrcRegs = 3;
reg_src(&new_inst.Src[0], src0, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[1], src1, SWIZ(X, Y, Z, W));
reg_src(&new_inst.Src[2], &ctx->tmp[A].src, SWIZ(X, Y, Z, W));
new_inst.Src[2].Register.Negate = true;
tctx->emit_instruction(tctx, &new_inst);
}
}