radeonsi: mark descriptor loads as using dynamically uniform indices

This tells LLVM to always use SMEM loads for descriptors. It fixes a
regression in piglit's arb_shader_storage_buffer_object/execution/indirect.shader_test
that was caused by LLVM r268259 (but the proper fix is really here in Mesa).

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index 1d6dc78..49c498d 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -94,7 +94,9 @@ struct si_shader_context
 
        LLVMTargetMachineRef tm;
 
+       unsigned uniform_md_kind;
        LLVMValueRef const_md;
+       LLVMValueRef empty_md;
        LLVMValueRef const_buffers[SI_NUM_CONST_BUFFERS];
        LLVMValueRef lds;
        LLVMValueRef *constants[SI_NUM_CONST_BUFFERS];
@@ -373,9 +375,12 @@ static void build_indexed_store(struct si_shader_context *ctx,
  *
  * \param base_ptr  Where the array starts.
  * \param index     The element index into the array.
+ * \param uniform   Whether the base_ptr and index can be assumed to be
+ *                  dynamically uniform
  */
 static LLVMValueRef build_indexed_load(struct si_shader_context *ctx,
-                                      LLVMValueRef base_ptr, LLVMValueRef index)
+                                      LLVMValueRef base_ptr, LLVMValueRef index,
+                                      bool uniform)
 {
        struct lp_build_tgsi_context *bld_base = &ctx->radeon_bld.soa.bld_base;
        struct gallivm_state *gallivm = bld_base->base.gallivm;
@@ -385,18 +390,20 @@ static LLVMValueRef build_indexed_load(struct si_shader_context *ctx,
        indices[1] = index;
 
        pointer = LLVMBuildGEP(gallivm->builder, base_ptr, indices, 2, "");
+       if (uniform)
+               LLVMSetMetadata(pointer, ctx->uniform_md_kind, ctx->empty_md);
        return LLVMBuildLoad(gallivm->builder, pointer, "");
 }
 
 /**
  * Do a load from &base_ptr[index], but also add a flag that it's loading
- * a constant.
+ * a constant from a dynamically uniform index.
  */
 static LLVMValueRef build_indexed_load_const(
        struct si_shader_context *ctx,
        LLVMValueRef base_ptr, LLVMValueRef index)
 {
-       LLVMValueRef result = build_indexed_load(ctx, base_ptr, index);
+       LLVMValueRef result = build_indexed_load(ctx, base_ptr, index, true);
        LLVMSetMetadata(result, 1, ctx->const_md);
        return result;
 }
@@ -679,12 +686,12 @@ static LLVMValueRef lds_load(struct lp_build_tgsi_context *bld_base,
        dw_addr = lp_build_add(&bld_base->uint_bld, dw_addr,
                            lp_build_const_int32(gallivm, swizzle));
 
-       value = build_indexed_load(ctx, ctx->lds, dw_addr);
+       value = build_indexed_load(ctx, ctx->lds, dw_addr, false);
        if (type == TGSI_TYPE_DOUBLE) {
                LLVMValueRef value2;
                dw_addr = lp_build_add(&bld_base->uint_bld, dw_addr,
                                       lp_build_const_int32(gallivm, swizzle + 1));
-               value2 = build_indexed_load(ctx, ctx->lds, dw_addr);
+               value2 = build_indexed_load(ctx, ctx->lds, dw_addr, false);
                return radeon_llvm_emit_fetch_double(bld_base, value, value2);
        }
 
@@ -4885,6 +4892,11 @@ static void create_meta_data(struct si_shader_context *ctx)
        args[2] = lp_build_const_int32(gallivm, 1);
 
        ctx->const_md = LLVMMDNodeInContext(gallivm->context, args, 3);
+
+       ctx->uniform_md_kind = LLVMGetMDKindIDInContext(gallivm->context,
+                                                       "amdgpu.uniform", 14);
+
+       ctx->empty_md = LLVMMDNodeInContext(gallivm->context, NULL, 0);
 }
 
 static void declare_streamout_params(struct si_shader_context *ctx,