freedreno/ir3: Use output type size to set OUTPUT_REG_HALF_PRECISION

Previously the A5XX_SP_FS_OUTPUT_REG_HALF_PRECISION was set depending
on whether half_precision was set in the shader key. With support for
mediump precision, it is possible to have different outputs use
different precisions. That means we can’t have a global shader state
to specify it. Instead it now tries to copy the half-float-ness
from the nir_variable for the output into the ir3_shader_variant. This
is then used to decide whether to set half-precision for each output.

The a6xx version is copied from the a5xx code but it has not been
tested.

v2. [Hyunjun Ko (zzoon@igalia.com)] There's the half flag recently
added, which represents precision based on IR3_REG_HALF. Now use this
flag to avoid duplication.

Signed-off-by: Rob Clark <robdclark@chromium.org>

src/gallium/drivers/freedreno/a5xx/fd5_program.c

@@ -606,8 +606,7 @@ fd5_program_emit(struct fd_context *ctx, struct fd_ringbuffer *ring,
 	OUT_PKT4(ring, REG_A5XX_SP_FS_OUTPUT_REG(0), 8);
 	for (i = 0; i < 8; i++) {
 		OUT_RING(ring, A5XX_SP_FS_OUTPUT_REG_REGID(color_regid[i]) |
-				COND(emit->key.half_precision,
-					A5XX_SP_FS_OUTPUT_REG_HALF_PRECISION));
+				COND(s[FS].v->outputs[i].half, A5XX_SP_FS_OUTPUT_REG_HALF_PRECISION));
 	}
 
 

src/gallium/drivers/freedreno/a6xx/fd6_program.c

@@ -626,11 +626,8 @@ setup_stateobj(struct fd_ringbuffer *ring, struct fd6_program_state *state,
 
 	OUT_PKT4(ring, REG_A6XX_SP_FS_OUTPUT_REG(0), 8);
 	for (i = 0; i < 8; i++) {
-		// TODO we could have a mix of half and full precision outputs,
-		// we really need to figure out half-precision from IR3_REG_HALF
 		OUT_RING(ring, A6XX_SP_FS_OUTPUT_REG_REGID(color_regid[i]) |
-				COND(false,
-					A6XX_SP_FS_OUTPUT_REG_HALF_PRECISION));
+				COND(s[FS].v->outputs[i].half, A6XX_SP_FS_OUTPUT_REG_HALF_PRECISION));
 	}
 
 	OUT_PKT4(ring, REG_A6XX_VPC_PACK, 1);