From: Rob Clark <robdclark@gmail.com>
Date: Sun, 21 Jan 2018 17:31:51 +0000 (-0500)
Subject: freedreno/ir3: don't lower fsat
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=942341bcd0128fb9d9caf68b33f603855e2f6d69;p=mesa.git

freedreno/ir3: don't lower fsat

Instead, if possible fold (sat) flag into src, otherwise use:

  (sat)max.f rD, rS, rS

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

diff --git a/src/gallium/drivers/freedreno/ir3/ir3.h b/src/gallium/drivers/freedreno/ir3/ir3.h
index 210df20b812..84235cc1cd2 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3.h
+++ b/src/gallium/drivers/freedreno/ir3/ir3.h
@@ -616,6 +616,8 @@ static inline bool is_same_type_mov(struct ir3_instruction *instr)
 		break;
 	case OPC_ABSNEG_F:
 	case OPC_ABSNEG_S:
+		if (instr->flags & IR3_INSTR_SAT)
+			return false;
 		break;
 	default:
 		return false;
diff --git a/src/gallium/drivers/freedreno/ir3/ir3_compiler_nir.c b/src/gallium/drivers/freedreno/ir3/ir3_compiler_nir.c
index 009dcb30fa5..72e0f4fe288 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3_compiler_nir.c
+++ b/src/gallium/drivers/freedreno/ir3/ir3_compiler_nir.c
@@ -964,6 +964,27 @@ emit_alu(struct ir3_context *ctx, nir_alu_instr *alu)
 	case nir_op_fmin:
 		dst[0] = ir3_MIN_F(b, src[0], 0, src[1], 0);
 		break;
+	case nir_op_fsat:
+		/* if there is just a single use of the src, and it supports
+		 * (sat) bit, we can just fold the (sat) flag back to the
+		 * src instruction and create a mov.  This is easier for cp
+		 * to eliminate.
+		 *
+		 * TODO probably opc_cat==4 is ok too
+		 */
+		if (alu->src[0].src.is_ssa &&
+				(list_length(&alu->src[0].src.ssa->uses) == 1) &&
+				((opc_cat(src[0]->opc) == 2) || (opc_cat(src[0]->opc) == 3))) {
+			src[0]->flags |= IR3_INSTR_SAT;
+			dst[0] = ir3_MOV(b, src[0], TYPE_U32);
+		} else {
+			/* otherwise generate a max.f that saturates.. blob does
+			 * similar (generating a cat2 mov using max.f)
+			 */
+			dst[0] = ir3_MAX_F(b, src[0], 0, src[0], 0);
+			dst[0]->flags |= IR3_INSTR_SAT;
+		}
+		break;
 	case nir_op_fmul:
 		dst[0] = ir3_MUL_F(b, src[0], 0, src[1], 0);
 		break;
diff --git a/src/gallium/drivers/freedreno/ir3/ir3_nir.c b/src/gallium/drivers/freedreno/ir3/ir3_nir.c
index 2393306e19c..81a46be914e 100644
--- a/src/gallium/drivers/freedreno/ir3/ir3_nir.c
+++ b/src/gallium/drivers/freedreno/ir3/ir3_nir.c
@@ -37,7 +37,6 @@
 
 static const nir_shader_compiler_options options = {
 		.lower_fpow = true,
-		.lower_fsat = true,
 		.lower_scmp = true,
 		.lower_flrp32 = true,
 		.lower_flrp64 = true,