[Mesa-dev] [PATCH 1/2] radeonsi: don't enable scratch just for SGPR spills

[Marek Olšák]

From: Marek Olšák <marek.olsak at amd.com>

Diff from shader-db:
  Scratch: 3221504 -> 17408 (-99.46 %) bytes per wave
---
 src/gallium/drivers/radeonsi/si_shader.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 6e8eefb..d392807 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -5825,6 +5825,18 @@ void si_shader_binary_read_config(struct radeon_shader_binary *binary,
 	unsigned i;
 	const unsigned char *config =
 		radeon_shader_binary_config_start(binary, symbol_offset);
+	bool really_needs_scratch = false;
+
+	/* LLVM adds SGPR spills to the scratch size.
+	 * Find out if we really need the scratch buffer.
+	 */
+	for (i = 0; i < binary->reloc_count; i++) {
+		const struct radeon_shader_reloc *reloc = &binary->relocs[i];
+
+		if (!strcmp(scratch_rsrc_dword0_symbol, reloc->name) ||
+		    !strcmp(scratch_rsrc_dword1_symbol, reloc->name))
+			really_needs_scratch = true;
+	}
 
 	/* XXX: We may be able to emit some of these values directly rather than
 	 * extracting fields to be emitted later.
@@ -5859,8 +5871,9 @@ void si_shader_binary_read_config(struct radeon_shader_binary *binary,
 		case R_0286E8_SPI_TMPRING_SIZE:
 		case R_00B860_COMPUTE_TMPRING_SIZE:
 			/* WAVESIZE is in units of 256 dwords. */
-			conf->scratch_bytes_per_wave =
-				G_00B860_WAVESIZE(value) * 256 * 4 * 1;
+			if (really_needs_scratch)
+				conf->scratch_bytes_per_wave =
+					G_00B860_WAVESIZE(value) * 256 * 4;
 			break;
 		default:
 			{
-- 
2.7.4