freedreno/ir3: use nopN encoding when possible

Use the (nopN) encoding for slightly denser shaders.. this lets us fold
nop instructions into the previous alu instruction in certain cases.

Shouldn't change the # of cycles a shader takes to execute, but reduces
the size.  (ex: glmark2 refract goes from 168 to 116 instructions)

Currently only enabled for a6xx, but I think we could enable this for
a5xx and possibly a4xx.

Signed-off-by: Rob Clark <[email protected]>

3 files changed, 35 insertions, 6 deletions

diff --git a/src/freedreno/ir3/ir3.c b/src/freedreno/ir3/ir3.c
index a4de1d3ab49..ed14c343faa 100644
--- a/src/freedreno/ir3/ir3.c
+++ b/src/freedreno/ir3/ir3.c
@@ -211,6 +211,18 @@ static int emit_cat2(struct ir3_instruction *instr, void *ptr,
 
 	iassert((instr->regs_count == 2) || (instr->regs_count == 3));
 
+	if (instr->nop) {
+		iassert(!instr->repeat);
+		iassert(instr->nop <= 3);
+
+		cat2->src1_r = instr->nop & 0x1;
+		cat2->src2_r = (instr->nop >> 1) & 0x1;
+	} else {
+		cat2->src1_r = !!(src1->flags & IR3_REG_R);
+		if (src2)
+			cat2->src2_r = !!(src2->flags & IR3_REG_R);
+	}
+
 	if (src1->flags & IR3_REG_RELATIV) {
 		iassert(src1->array.offset < (1 << 10));
 		cat2->rel1.src1      = reg(src1, info, instr->repeat,
@@ -232,7 +244,6 @@ static int emit_cat2(struct ir3_instruction *instr, void *ptr,
 	cat2->src1_im  = !!(src1->flags & IR3_REG_IMMED);
 	cat2->src1_neg = !!(src1->flags & (IR3_REG_FNEG | IR3_REG_SNEG | IR3_REG_BNOT));
 	cat2->src1_abs = !!(src1->flags & (IR3_REG_FABS | IR3_REG_SABS));
-	cat2->src1_r   = !!(src1->flags & IR3_REG_R);
 
 	if (src2) {
 		iassert((src2->flags & IR3_REG_IMMED) ||
@@ -260,7 +271,6 @@ static int emit_cat2(struct ir3_instruction *instr, void *ptr,
 		cat2->src2_im  = !!(src2->flags & IR3_REG_IMMED);
 		cat2->src2_neg = !!(src2->flags & (IR3_REG_FNEG | IR3_REG_SNEG | IR3_REG_BNOT));
 		cat2->src2_abs = !!(src2->flags & (IR3_REG_FABS | IR3_REG_SABS));
-		cat2->src2_r   = !!(src2->flags & IR3_REG_R);
 	}
 
 	cat2->dst      = reg(dst, info, instr->repeat,
@@ -312,6 +322,17 @@ static int emit_cat3(struct ir3_instruction *instr, void *ptr,
 	iassert(!((src2->flags ^ src_flags) & IR3_REG_HALF));
 	iassert(!((src3->flags ^ src_flags) & IR3_REG_HALF));
 
+	if (instr->nop) {
+		iassert(!instr->repeat);
+		iassert(instr->nop <= 3);
+
+		cat3->src1_r = instr->nop & 0x1;
+		cat3->src2_r = (instr->nop >> 1) & 0x1;
+	} else {
+		cat3->src1_r = !!(src1->flags & IR3_REG_R);
+		cat3->src2_r = !!(src2->flags & IR3_REG_R);
+	}
+
 	if (src1->flags & IR3_REG_RELATIV) {
 		iassert(src1->array.offset < (1 << 10));
 		cat3->rel1.src1      = reg(src1, info, instr->repeat,
@@ -331,14 +352,11 @@ static int emit_cat3(struct ir3_instruction *instr, void *ptr,
 	}
 
 	cat3->src1_neg = !!(src1->flags & (IR3_REG_FNEG | IR3_REG_SNEG | IR3_REG_BNOT));
-	cat3->src1_r   = !!(src1->flags & IR3_REG_R);
 
 	cat3->src2     = reg(src2, info, instr->repeat,
 			IR3_REG_CONST | IR3_REG_R | IR3_REG_HALF | absneg);
 	cat3->src2_c   = !!(src2->flags & IR3_REG_CONST);
 	cat3->src2_neg = !!(src2->flags & (IR3_REG_FNEG | IR3_REG_SNEG | IR3_REG_BNOT));
-	cat3->src2_r   = !!(src2->flags & IR3_REG_R);
-
 
 	if (src3->flags & IR3_REG_RELATIV) {
 		iassert(src3->array.offset < (1 << 10));
diff --git a/src/freedreno/ir3/ir3.h b/src/freedreno/ir3/ir3.h
index 36d645f0b50..27a52c54ad4 100644
--- a/src/freedreno/ir3/ir3.h
+++ b/src/freedreno/ir3/ir3.h
@@ -212,7 +212,8 @@ struct ir3_instruction {
 		IR3_INSTR_MARK  = 0x1000,
 		IR3_INSTR_UNUSED= 0x2000,
 	} flags;
-	int repeat;
+	uint8_t repeat;
+	uint8_t nop;
 #ifdef DEBUG
 	unsigned regs_max;
 #endif
diff --git a/src/freedreno/ir3/ir3_legalize.c b/src/freedreno/ir3/ir3_legalize.c
index 00f0c9c9b8d..b14a789efb2 100644
--- a/src/freedreno/ir3/ir3_legalize.c
+++ b/src/freedreno/ir3/ir3_legalize.c
@@ -200,6 +200,16 @@ legalize_block(struct ir3_legalize_ctx *ctx, struct ir3_block *block)
 				last->flags |= n->flags;
 				continue;
 			}
+
+			/* NOTE: I think the nopN encoding works for a5xx and
+			 * probably a4xx, but not a3xx.  So far only tested on
+			 * a6xx.
+			 */
+			if ((ctx->compiler->gpu_id >= 600) && !n->flags && (last->nop < 3) &&
+					((opc_cat(last->opc) == 2) || (opc_cat(last->opc) == 3))) {
+				last->nop++;
+				continue;
+			}
 		}
 
 		list_addtail(&n->node, &block->instr_list);