radv/ac: use tex_lz if we can.

Looking at some Talos shaders vs radeonsi, I noticed they use
tex_lz in a few places, so we should be able to as well.

Reviewed-by: Bas Nieuwenhuizen <basni@google.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/src/amd/common/ac_nir_to_llvm.c b/src/amd/common/ac_nir_to_llvm.c
index 6062d3af543ba421b7b18b6f7da1ef07cab4d16d..514c9e9ca35b8141c3325f67afd9cf39cb876e11 100644 (file)
--- a/src/amd/common/ac_nir_to_llvm.c
+++ b/src/amd/common/ac_nir_to_llvm.c
@@ -2049,6 +2049,7 @@ static LLVMValueRef radv_lower_gather4_integer(struct nir_to_llvm_context *ctx,
 
 static LLVMValueRef build_tex_intrinsic(struct nir_to_llvm_context *ctx,
                                        nir_tex_instr *instr,
+                                       bool lod_is_zero,
                                        struct ac_image_args *args)
 {
        if (instr->sampler_dim == GLSL_SAMPLER_DIM_BUF) {
@@ -2074,7 +2075,10 @@ static LLVMValueRef build_tex_intrinsic(struct nir_to_llvm_context *ctx,
                args->bias = true;
                break;
        case nir_texop_txl:
-               args->lod = true;
+               if (lod_is_zero)
+                       args->level_zero = true;
+               else
+                       args->lod = true;
                break;
        case nir_texop_txs:
        case nir_texop_query_levels:
@@ -4203,7 +4207,7 @@ static void visit_tex(struct nir_to_llvm_context *ctx, nir_tex_instr *instr)
        LLVMValueRef derivs[6];
        unsigned chan, count = 0;
        unsigned const_src = 0, num_deriv_comp = 0;
-
+       bool lod_is_zero = false;
        tex_fetch_ptrs(ctx, instr, &res_ptr, &samp_ptr, &fmask_ptr);
 
        for (unsigned i = 0; i < instr->num_srcs; i++) {
@@ -4223,9 +4227,14 @@ static void visit_tex(struct nir_to_llvm_context *ctx, nir_tex_instr *instr)
                case nir_tex_src_bias:
                        bias = get_src(ctx, instr->src[i].src);
                        break;
-               case nir_tex_src_lod:
+               case nir_tex_src_lod: {
+                       nir_const_value *val = nir_src_as_const_value(instr->src[i].src);
+
+                       if (val && val->i32[0] == 0)
+                               lod_is_zero = true;
                        lod = get_src(ctx, instr->src[i].src);
                        break;
+               }
                case nir_tex_src_ms_index:
                        sample_index = get_src(ctx, instr->src[i].src);
                        break;
@@ -4370,7 +4379,8 @@ static void visit_tex(struct nir_to_llvm_context *ctx, nir_tex_instr *instr)
        }
 
        /* Pack LOD */
-       if ((instr->op == nir_texop_txl || instr->op == nir_texop_txf) && lod) {
+       if (lod && ((instr->op == nir_texop_txl && !lod_is_zero) ||
+                   instr->op == nir_texop_txf)) {
                address[count++] = lod;
        } else if (instr->op == nir_texop_txf_ms && sample_index) {
                address[count++] = sample_index;
@@ -4401,7 +4411,7 @@ static void visit_tex(struct nir_to_llvm_context *ctx, nir_tex_instr *instr)
                                   fmask_ptr, NULL,
                                   txf_address, txf_count, 0xf);
 
-               result = build_tex_intrinsic(ctx, instr, &txf_args);
+               result = build_tex_intrinsic(ctx, instr, false, &txf_args);
 
                result = LLVMBuildExtractElement(ctx->builder, result, ctx->i32zero, "");
                result = emit_int_cmp(ctx, LLVMIntEQ, result, ctx->i32zero);
@@ -4446,7 +4456,7 @@ static void visit_tex(struct nir_to_llvm_context *ctx, nir_tex_instr *instr)
        set_tex_fetch_args(ctx, &args, instr, instr->op,
                           res_ptr, samp_ptr, address, count, dmask);
 
-       result = build_tex_intrinsic(ctx, instr, &args);
+       result = build_tex_intrinsic(ctx, instr, lod_is_zero, &args);
 
        if (instr->op == nir_texop_query_levels)
                result = LLVMBuildExtractElement(ctx->builder, result, LLVMConstInt(ctx->i32, 3, false), "");