Mesa (master): freedreno/ir3: add 'high' register class

Rob Clark robclark at kemper.freedesktop.org
Mon Apr 17 18:01:20 UTC 2017


Module: Mesa
Branch: master
Commit: 15fe9b2347931f474d751dde04cc30f91e6c2d26
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=15fe9b2347931f474d751dde04cc30f91e6c2d26

Author: Rob Clark <robdclark at gmail.com>
Date:   Wed Apr 12 09:45:16 2017 -0400

freedreno/ir3: add 'high' register class

For compute shaders, we need to be able to allocate some "high"
registers (r48.x to r55.w).  (Possibly these are global to all threads
in a warp?)  Add a new register class to handle this.

Signed-off-by: Rob Clark <robdclark at gmail.com>

---

 src/gallium/drivers/freedreno/ir3/ir3.c    |   2 +-
 src/gallium/drivers/freedreno/ir3/ir3.h    |  32 +++---
 src/gallium/drivers/freedreno/ir3/ir3_ra.c | 164 +++++++++++++++++++----------
 3 files changed, 131 insertions(+), 67 deletions(-)

diff --git a/src/gallium/drivers/freedreno/ir3/ir3.c b/src/gallium/drivers/freedreno/ir3/ir3.c
index c5a030282d..ff2c342c35 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3.c
+++ b/src/gallium/drivers/freedreno/ir3/ir3.c
@@ -106,7 +106,7 @@ static uint32_t reg(struct ir3_register *reg, struct ir3_info *info,
 			info->max_const = MAX2(info->max_const, max);
 		} else if (val.num == 63) {
 			/* ignore writes to dummy register r63.x */
-		} else if ((max != REG_A0) && (max != REG_P0)) {
+		} else if (max < 48) {
 			if (reg->flags & IR3_REG_HALF) {
 				info->max_half_reg = MAX2(info->max_half_reg, max);
 			} else {
diff --git a/src/gallium/drivers/freedreno/ir3/ir3.h b/src/gallium/drivers/freedreno/ir3/ir3.h
index 480b27ce5d..bbe903d9d1 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3.h
+++ b/src/gallium/drivers/freedreno/ir3/ir3.h
@@ -58,8 +58,14 @@ struct ir3_register {
 		IR3_REG_CONST  = 0x001,
 		IR3_REG_IMMED  = 0x002,
 		IR3_REG_HALF   = 0x004,
-		IR3_REG_RELATIV= 0x008,
-		IR3_REG_R      = 0x010,
+		/* high registers are used for some things in compute shaders,
+		 * for example.  Seems to be for things that are global to all
+		 * threads in a wave, so possibly these are global/shared by
+		 * all the threads in the wave?
+		 */
+		IR3_REG_HIGH   = 0x008,
+		IR3_REG_RELATIV= 0x010,
+		IR3_REG_R      = 0x020,
 		/* Most instructions, it seems, can do float abs/neg but not
 		 * integer.  The CP pass needs to know what is intended (int or
 		 * float) in order to do the right thing.  For this reason the
@@ -68,23 +74,23 @@ struct ir3_register {
 		 * bitwise not, so split that out into a new flag to make it
 		 * more clear.
 		 */
-		IR3_REG_FNEG   = 0x020,
-		IR3_REG_FABS   = 0x040,
-		IR3_REG_SNEG   = 0x080,
-		IR3_REG_SABS   = 0x100,
-		IR3_REG_BNOT   = 0x200,
-		IR3_REG_EVEN   = 0x400,
-		IR3_REG_POS_INF= 0x800,
+		IR3_REG_FNEG   = 0x040,
+		IR3_REG_FABS   = 0x080,
+		IR3_REG_SNEG   = 0x100,
+		IR3_REG_SABS   = 0x200,
+		IR3_REG_BNOT   = 0x400,
+		IR3_REG_EVEN   = 0x800,
+		IR3_REG_POS_INF= 0x1000,
 		/* (ei) flag, end-input?  Set on last bary, presumably to signal
 		 * that the shader needs no more input:
 		 */
-		IR3_REG_EI     = 0x1000,
+		IR3_REG_EI     = 0x2000,
 		/* meta-flags, for intermediate stages of IR, ie.
 		 * before register assignment is done:
 		 */
-		IR3_REG_SSA    = 0x2000,   /* 'instr' is ptr to assigning instr */
-		IR3_REG_ARRAY  = 0x4000,
-		IR3_REG_PHI_SRC= 0x8000,   /* phi src, regs[0]->instr points to phi */
+		IR3_REG_SSA    = 0x4000,   /* 'instr' is ptr to assigning instr */
+		IR3_REG_ARRAY  = 0x8000,
+		IR3_REG_PHI_SRC= 0x10000,  /* phi src, regs[0]->instr points to phi */
 
 	} flags;
 	union {
diff --git a/src/gallium/drivers/freedreno/ir3/ir3_ra.c b/src/gallium/drivers/freedreno/ir3/ir3_ra.c
index f70c779525..26c1508fbd 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3_ra.c
+++ b/src/gallium/drivers/freedreno/ir3/ir3_ra.c
@@ -95,25 +95,78 @@ static const unsigned half_class_sizes[] = {
 	1, 2, 3, 4,
 };
 #define half_class_count  ARRAY_SIZE(half_class_sizes)
-#define total_class_count (class_count + half_class_count)
+
+/* seems to just be used for compute shaders?  Seems like vec1 and vec3
+ * are sufficient (for now?)
+ */
+static const unsigned high_class_sizes[] = {
+	1, 3,
+};
+#define high_class_count ARRAY_SIZE(high_class_sizes)
+
+#define total_class_count (class_count + half_class_count + high_class_count)
 
 /* Below a0.x are normal regs.  RA doesn't need to assign a0.x/p0.x. */
-#define NUM_REGS             (4 * 48)
+#define NUM_REGS             (4 * 48)  /* r0 to r47 */
+#define NUM_HIGH_REGS        (4 * 8)   /* r48 to r55 */
+#define FIRST_HIGH_REG       (4 * 48)
 /* Number of virtual regs in a given class: */
 #define CLASS_REGS(i)        (NUM_REGS - (class_sizes[i] - 1))
 #define HALF_CLASS_REGS(i)   (NUM_REGS - (half_class_sizes[i] - 1))
+#define HIGH_CLASS_REGS(i)   (NUM_HIGH_REGS - (high_class_sizes[i] - 1))
+
+#define HALF_OFFSET          (class_count)
+#define HIGH_OFFSET          (class_count + half_class_count)
 
 /* register-set, created one time, used for all shaders: */
 struct ir3_ra_reg_set {
 	struct ra_regs *regs;
 	unsigned int classes[class_count];
 	unsigned int half_classes[half_class_count];
+	unsigned int high_classes[high_class_count];
 	/* maps flat virtual register space to base gpr: */
 	uint16_t *ra_reg_to_gpr;
 	/* maps cls,gpr to flat virtual register space: */
 	uint16_t **gpr_to_ra_reg;
 };
 
+static void
+build_q_values(unsigned int **q_values, unsigned off,
+		const unsigned *sizes, unsigned count)
+{
+	for (unsigned i = 0; i < count; i++) {
+		q_values[i + off] = rzalloc_array(q_values, unsigned, total_class_count);
+
+		/* From register_allocate.c:
+		 *
+		 * q(B,C) (indexed by C, B is this register class) in
+		 * Runeson/Nyström paper.  This is "how many registers of B could
+		 * the worst choice register from C conflict with".
+		 *
+		 * If we just let the register allocation algorithm compute these
+		 * values, is extremely expensive.  However, since all of our
+		 * registers are laid out, we can very easily compute them
+		 * ourselves.  View the register from C as fixed starting at GRF n
+		 * somewhere in the middle, and the register from B as sliding back
+		 * and forth.  Then the first register to conflict from B is the
+		 * one starting at n - class_size[B] + 1 and the last register to
+		 * conflict will start at n + class_size[B] - 1.  Therefore, the
+		 * number of conflicts from B is class_size[B] + class_size[C] - 1.
+		 *
+		 *   +-+-+-+-+-+-+     +-+-+-+-+-+-+
+		 * B | | | | | |n| --> | | | | | | |
+		 *   +-+-+-+-+-+-+     +-+-+-+-+-+-+
+		 *             +-+-+-+-+-+
+		 * C           |n| | | | |
+		 *             +-+-+-+-+-+
+		 *
+		 * (Idea copied from brw_fs_reg_allocate.cpp)
+		 */
+		for (unsigned j = 0; j < count; j++)
+			q_values[i + off][j + off] = sizes[i] + sizes[j] - 1;
+	}
+}
+
 /* One-time setup of RA register-set, which describes all the possible
  * "virtual" registers and their interferences.  Ie. double register
  * occupies (and conflicts with) two single registers, and so forth.
@@ -135,7 +188,7 @@ struct ir3_ra_reg_set *
 ir3_ra_alloc_reg_set(void *memctx)
 {
 	struct ir3_ra_reg_set *set = rzalloc(memctx, struct ir3_ra_reg_set);
-	unsigned ra_reg_count, reg, first_half_reg;
+	unsigned ra_reg_count, reg, first_half_reg, first_high_reg, base;
 	unsigned int **q_values;
 
 	/* calculate # of regs across all classes: */
@@ -144,50 +197,15 @@ ir3_ra_alloc_reg_set(void *memctx)
 		ra_reg_count += CLASS_REGS(i);
 	for (unsigned i = 0; i < half_class_count; i++)
 		ra_reg_count += HALF_CLASS_REGS(i);
+	for (unsigned i = 0; i < high_class_count; i++)
+		ra_reg_count += HIGH_CLASS_REGS(i);
 
 	/* allocate and populate q_values: */
 	q_values = ralloc_array(set, unsigned *, total_class_count);
-	for (unsigned i = 0; i < class_count; i++) {
-		q_values[i] = rzalloc_array(q_values, unsigned, total_class_count);
 
-		/* From register_allocate.c:
-		 *
-		 * q(B,C) (indexed by C, B is this register class) in
-		 * Runeson/Nyström paper.  This is "how many registers of B could
-		 * the worst choice register from C conflict with".
-		 *
-		 * If we just let the register allocation algorithm compute these
-		 * values, is extremely expensive.  However, since all of our
-		 * registers are laid out, we can very easily compute them
-		 * ourselves.  View the register from C as fixed starting at GRF n
-		 * somewhere in the middle, and the register from B as sliding back
-		 * and forth.  Then the first register to conflict from B is the
-		 * one starting at n - class_size[B] + 1 and the last register to
-		 * conflict will start at n + class_size[B] - 1.  Therefore, the
-		 * number of conflicts from B is class_size[B] + class_size[C] - 1.
-		 *
-		 *   +-+-+-+-+-+-+     +-+-+-+-+-+-+
-		 * B | | | | | |n| --> | | | | | | |
-		 *   +-+-+-+-+-+-+     +-+-+-+-+-+-+
-		 *             +-+-+-+-+-+
-		 * C           |n| | | | |
-		 *             +-+-+-+-+-+
-		 *
-		 * (Idea copied from brw_fs_reg_allocate.cpp)
-		 */
-		for (unsigned j = 0; j < class_count; j++)
-			q_values[i][j] = class_sizes[i] + class_sizes[j] - 1;
-	}
-
-	for (unsigned i = class_count; i < total_class_count; i++) {
-		q_values[i] = ralloc_array(q_values, unsigned, total_class_count);
-
-		/* see comment above: */
-		for (unsigned j = class_count; j < total_class_count; j++) {
-			q_values[i][j] = half_class_sizes[i - class_count] +
-					half_class_sizes[j - class_count] - 1;
-		}
-	}
+	build_q_values(q_values, 0, class_sizes, class_count);
+	build_q_values(q_values, HALF_OFFSET, half_class_sizes, half_class_count);
+	build_q_values(q_values, HIGH_OFFSET, high_class_sizes, high_class_count);
 
 	/* allocate the reg-set.. */
 	set->regs = ra_alloc_reg_set(set, ra_reg_count, true);
@@ -215,18 +233,19 @@ ir3_ra_alloc_reg_set(void *memctx)
 	}
 
 	first_half_reg = reg;
+	base = HALF_OFFSET;
 
 	for (unsigned i = 0; i < half_class_count; i++) {
 		set->half_classes[i] = ra_alloc_reg_class(set->regs);
 
-		set->gpr_to_ra_reg[class_count + i] =
-				ralloc_array(set, uint16_t, CLASS_REGS(i));
+		set->gpr_to_ra_reg[base + i] =
+				ralloc_array(set, uint16_t, HALF_CLASS_REGS(i));
 
 		for (unsigned j = 0; j < HALF_CLASS_REGS(i); j++) {
 			ra_class_add_reg(set->regs, set->half_classes[i], reg);
 
 			set->ra_reg_to_gpr[reg] = j;
-			set->gpr_to_ra_reg[class_count + i][j] = reg;
+			set->gpr_to_ra_reg[base + i][j] = reg;
 
 			for (unsigned br = j; br < j + half_class_sizes[i]; br++)
 				ra_add_transitive_reg_conflict(set->regs, br + first_half_reg, reg);
@@ -235,6 +254,29 @@ ir3_ra_alloc_reg_set(void *memctx)
 		}
 	}
 
+	first_high_reg = reg;
+	base = HIGH_OFFSET;
+
+	for (unsigned i = 0; i < high_class_count; i++) {
+		set->high_classes[i] = ra_alloc_reg_class(set->regs);
+
+		set->gpr_to_ra_reg[base + i] =
+				ralloc_array(set, uint16_t, HIGH_CLASS_REGS(i));
+
+		for (unsigned j = 0; j < HIGH_CLASS_REGS(i); j++) {
+			ra_class_add_reg(set->regs, set->high_classes[i], reg);
+
+			set->ra_reg_to_gpr[reg] = j;
+			set->gpr_to_ra_reg[base + i][j] = reg;
+
+			for (unsigned br = j; br < j + high_class_sizes[i]; br++)
+				ra_add_transitive_reg_conflict(set->regs, br + first_high_reg, reg);
+
+			reg++;
+		}
+	}
+
+
 	ra_set_finalize(set->regs, q_values);
 
 	ralloc_free(q_values);
@@ -287,13 +329,23 @@ is_half(struct ir3_instruction *instr)
 	return !!(instr->regs[0]->flags & IR3_REG_HALF);
 }
 
+static bool
+is_high(struct ir3_instruction *instr)
+{
+	return !!(instr->regs[0]->flags & IR3_REG_HIGH);
+}
+
 static int
-size_to_class(unsigned sz, bool half)
+size_to_class(unsigned sz, bool half, bool high)
 {
-	if (half) {
+	if (high) {
+		for (unsigned i = 0; i < high_class_count; i++)
+			if (high_class_sizes[i] >= sz)
+				return i + HIGH_OFFSET;
+	} else if (half) {
 		for (unsigned i = 0; i < half_class_count; i++)
 			if (half_class_sizes[i] >= sz)
-				return i + class_count;
+				return i + HALF_OFFSET;
 	} else {
 		for (unsigned i = 0; i < class_count; i++)
 			if (class_sizes[i] >= sz)
@@ -497,7 +549,7 @@ ra_block_find_definers(struct ir3_ra_ctx *ctx, struct ir3_block *block)
 			id->defn = instr;
 		} else {
 			id->defn = get_definer(ctx, instr, &id->sz, &id->off);
-			id->cls = size_to_class(id->sz, is_half(id->defn));
+			id->cls = size_to_class(id->sz, is_half(id->defn), is_high(id->defn));
 		}
 	}
 }
@@ -710,9 +762,12 @@ ra_block_compute_live_ranges(struct ir3_ra_ctx *ctx, struct ir3_block *block)
 
 				def(name, id->defn);
 
-				if (is_half(id->defn)) {
+				if (is_high(id->defn)) {
 					ra_set_node_class(ctx->g, name,
-							ctx->set->half_classes[id->cls - class_count]);
+							ctx->set->high_classes[id->cls - HIGH_OFFSET]);
+				} else if (is_half(id->defn)) {
+					ra_set_node_class(ctx->g, name,
+							ctx->set->half_classes[id->cls - HALF_OFFSET]);
 				} else {
 					ra_set_node_class(ctx->g, name,
 							ctx->set->classes[id->cls]);
@@ -981,6 +1036,9 @@ reg_assign(struct ir3_ra_ctx *ctx, struct ir3_register *reg,
 
 		debug_assert(!(reg->flags & IR3_REG_RELATIV));
 
+		if (is_high(id->defn))
+			num += FIRST_HIGH_REG;
+
 		reg->num = num;
 		reg->flags &= ~(IR3_REG_SSA | IR3_REG_PHI_SRC);
 
@@ -1029,7 +1087,7 @@ ra_alloc(struct ir3_ra_ctx *ctx)
 		unsigned i = 0, j;
 		if (ctx->frag_face && (i < ir->ninputs) && ir->inputs[i]) {
 			struct ir3_instruction *instr = ir->inputs[i];
-			int cls = size_to_class(1, true);
+			int cls = size_to_class(1, true, false);
 			unsigned name = __ra_name(ctx, cls, instr);
 			unsigned reg = ctx->set->gpr_to_ra_reg[cls][0];
 




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