radeonsi: don't fetch 8 dwords for samplerBuffer and imageBuffer

The compiler doesn't shrink s_load_dwordx8, so we always wasted 4 SGPRs.
Also, the extraction of the descriptor created some really ugly asm code
with lots of VALU bitwise ops and v_readfirstlane.

Totals from *affected* shaders:
SGPRS: 13880 -> 13253 (-4.52 %)
VGPRS: 15200 -> 15088 (-0.74 %)
Code Size: 499864 -> 459816 (-8.01 %) bytes
Max Waves: 1554 -> 1564 (0.64 %)

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index e434f3af4a4e6e39157cdf428438fdb3ce4ad31c..1e3be620e31c93bb341698e04744a59c67c3a319 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -3114,7 +3114,7 @@ static LLVMValueRef get_buffer_size(
        LLVMBuilderRef builder = gallivm->builder;
        LLVMValueRef size =
                LLVMBuildExtractElement(builder, descriptor,
-                                       lp_build_const_int32(gallivm, 6), "");
+                                       lp_build_const_int32(gallivm, 2), "");
 
        if (ctx->screen->b.chip_class >= VI) {
                /* On VI, the descriptor contains the size in bytes,
@@ -3123,7 +3123,7 @@ static LLVMValueRef get_buffer_size(
                 */
                LLVMValueRef stride =
                        LLVMBuildExtractElement(builder, descriptor,
-                                               lp_build_const_int32(gallivm, 5), "");
+                                               lp_build_const_int32(gallivm, 1), "");
                stride = LLVMBuildLShr(builder, stride,
                                       lp_build_const_int32(gallivm, 16), "");
                stride = LLVMBuildAnd(builder, stride,
@@ -3278,6 +3278,12 @@ static LLVMValueRef force_dcc_off(struct si_shader_context *ctx,
        }
 }
 
+static LLVMTypeRef const_array(LLVMTypeRef elem_type, int num_elements)
+{
+       return LLVMPointerType(LLVMArrayType(elem_type, num_elements),
+                              CONST_ADDR_SPACE);
+}
+
 /**
  * Load the resource descriptor for \p image.
  */
@@ -3319,6 +3325,19 @@ image_fetch_rsrc(
                                                   SI_NUM_IMAGES);
        }
 
+       if (target == TGSI_TEXTURE_BUFFER) {
+               LLVMBuilderRef builder = ctx->gallivm.builder;
+
+               rsrc_ptr = LLVMBuildPointerCast(builder, rsrc_ptr,
+                                               const_array(ctx->v4i32, 0), "");
+               index = LLVMBuildMul(builder, index,
+                                    LLVMConstInt(ctx->i32, 2, 0), "");
+               index = LLVMBuildAdd(builder, index,
+                                    LLVMConstInt(ctx->i32, 1, 0), "");
+               *rsrc = build_indexed_load_const(ctx, rsrc_ptr, index);
+               return;
+       }
+
        tmp = build_indexed_load_const(ctx, rsrc_ptr, index);
        if (dcc_off)
                tmp = force_dcc_off(ctx, tmp);
@@ -3393,25 +3412,6 @@ static void image_append_args(
        emit_data->args[emit_data->arg_count++] = da;
 }
 
-/**
- * Given a 256 bit resource, extract the top half (which stores the buffer
- * resource in the case of textures and images).
- */
-static LLVMValueRef extract_rsrc_top_half(
-               struct si_shader_context *ctx,
-               LLVMValueRef rsrc)
-{
-       struct gallivm_state *gallivm = &ctx->gallivm;
-       struct lp_build_tgsi_context *bld_base = &ctx->soa.bld_base;
-       LLVMTypeRef v2i128 = LLVMVectorType(ctx->i128, 2);
-
-       rsrc = LLVMBuildBitCast(gallivm->builder, rsrc, v2i128, "");
-       rsrc = LLVMBuildExtractElement(gallivm->builder, rsrc, bld_base->uint_bld.one, "");
-       rsrc = LLVMBuildBitCast(gallivm->builder, rsrc, ctx->v4i32, "");
-
-       return rsrc;
-}
-
 /**
  * Append the resource and indexing arguments for buffer intrinsics.
  *
@@ -3473,7 +3473,6 @@ static void load_fetch_args(
                coords = image_fetch_coords(bld_base, inst, 1);
 
                if (target == TGSI_TEXTURE_BUFFER) {
-                       rsrc = extract_rsrc_top_half(ctx, rsrc);
                        buffer_append_args(ctx, emit_data, rsrc, coords,
                                        bld_base->uint_bld.zero, false);
                } else {
@@ -3681,8 +3680,6 @@ static void store_fetch_args(
 
                if (target == TGSI_TEXTURE_BUFFER) {
                        image_fetch_rsrc(bld_base, &memory, true, target, &rsrc);
-
-                       rsrc = extract_rsrc_top_half(ctx, rsrc);
                        buffer_append_args(ctx, emit_data, rsrc, coords,
                                        bld_base->uint_bld.zero, false);
                } else {
@@ -3885,7 +3882,6 @@ static void atomic_fetch_args(
                coords = image_fetch_coords(bld_base, inst, 1);
 
                if (target == TGSI_TEXTURE_BUFFER) {
-                       rsrc = extract_rsrc_top_half(ctx, rsrc);
                        buffer_append_args(ctx, emit_data, rsrc, coords,
                                           bld_base->uint_bld.zero, true);
                } else {
@@ -4129,16 +4125,11 @@ static const struct lp_build_tgsi_action tex_action;
 
 enum desc_type {
        DESC_IMAGE,
+       DESC_BUFFER,
        DESC_FMASK,
-       DESC_SAMPLER
+       DESC_SAMPLER,
 };
 
-static LLVMTypeRef const_array(LLVMTypeRef elem_type, int num_elements)
-{
-       return LLVMPointerType(LLVMArrayType(elem_type, num_elements),
-                              CONST_ADDR_SPACE);
-}
-
 /**
  * Load an image view, fmask view. or sampler state descriptor.
  */
@@ -4154,6 +4145,13 @@ static LLVMValueRef load_sampler_desc_custom(struct si_shader_context *ctx,
                /* The image is at [0:7]. */
                index = LLVMBuildMul(builder, index, LLVMConstInt(ctx->i32, 2, 0), "");
                break;
+       case DESC_BUFFER:
+               /* The buffer is in [4:7]. */
+               index = LLVMBuildMul(builder, index, LLVMConstInt(ctx->i32, 4, 0), "");
+               index = LLVMBuildAdd(builder, index, LLVMConstInt(ctx->i32, 1, 0), "");
+               list = LLVMBuildPointerCast(builder, list,
+                                           const_array(ctx->v4i32, 0), "");
+               break;
        case DESC_FMASK:
                /* The FMASK is at [8:15]. */
                index = LLVMBuildMul(builder, index, LLVMConstInt(ctx->i32, 2, 0), "");
@@ -4235,21 +4233,25 @@ static void tex_fetch_ptrs(
                index = LLVMConstInt(ctx->i32, sampler_index, 0);
        }
 
-       *res_ptr = load_sampler_desc(ctx, index, DESC_IMAGE);
+       if (target == TGSI_TEXTURE_BUFFER)
+               *res_ptr = load_sampler_desc(ctx, index, DESC_BUFFER);
+       else
+               *res_ptr = load_sampler_desc(ctx, index, DESC_IMAGE);
+
+       if (samp_ptr)
+               *samp_ptr = NULL;
+       if (fmask_ptr)
+               *fmask_ptr = NULL;
 
        if (target == TGSI_TEXTURE_2D_MSAA ||
            target == TGSI_TEXTURE_2D_ARRAY_MSAA) {
-               if (samp_ptr)
-                       *samp_ptr = NULL;
                if (fmask_ptr)
                        *fmask_ptr = load_sampler_desc(ctx, index, DESC_FMASK);
-       } else {
+       } else if (target != TGSI_TEXTURE_BUFFER) {
                if (samp_ptr) {
                        *samp_ptr = load_sampler_desc(ctx, index, DESC_SAMPLER);
                        *samp_ptr = sici_fix_sampler_aniso(ctx, *res_ptr, *samp_ptr);
                }
-               if (fmask_ptr)
-                       *fmask_ptr = NULL;
        }
 }
 
@@ -4258,8 +4260,6 @@ static void txq_fetch_args(
        struct lp_build_emit_data *emit_data)
 {
        struct si_shader_context *ctx = si_shader_context(bld_base);
-       struct gallivm_state *gallivm = bld_base->base.gallivm;
-       LLVMBuilderRef builder = gallivm->builder;
        const struct tgsi_full_instruction *inst = emit_data->inst;
        unsigned target = inst->Texture.Texture;
        LLVMValueRef res_ptr;
@@ -4269,8 +4269,7 @@ static void txq_fetch_args(
 
        if (target == TGSI_TEXTURE_BUFFER) {
                /* Read the size from the buffer descriptor directly. */
-               LLVMValueRef res = LLVMBuildBitCast(builder, res_ptr, ctx->v8i32, "");
-               emit_data->args[0] = get_buffer_size(bld_base, res);
+               emit_data->args[0] = get_buffer_size(bld_base, res_ptr);
                return;
        }
 
@@ -4338,16 +4337,9 @@ static void tex_fetch_args(
        tex_fetch_ptrs(bld_base, emit_data, &res_ptr, &samp_ptr, &fmask_ptr);
 
        if (target == TGSI_TEXTURE_BUFFER) {
-               LLVMTypeRef v2i128 = LLVMVectorType(ctx->i128, 2);
-
-               /* Bitcast and truncate v8i32 to v16i8. */
-               LLVMValueRef res = res_ptr;
-               res = LLVMBuildBitCast(gallivm->builder, res, v2i128, "");
-               res = LLVMBuildExtractElement(gallivm->builder, res, bld_base->uint_bld.one, "");
-               res = LLVMBuildBitCast(gallivm->builder, res, ctx->v16i8, "");
-
                emit_data->dst_type = ctx->v4f32;
-               emit_data->args[0] = res;
+               emit_data->args[0] = LLVMBuildBitCast(gallivm->builder, res_ptr,
+                                                     ctx->v16i8, "");
                emit_data->args[1] = bld_base->uint_bld.zero;
                emit_data->args[2] = lp_build_emit_fetch(bld_base, emit_data->inst, 0, TGSI_CHAN_X);
                emit_data->arg_count = 3;