ac/nir: split 8-bit load/store to global memory on GFX6

Due to possible alignment issues, make sure to split loads/stores
of 8-bit vectors.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4339>

diff --git a/src/amd/llvm/ac_nir_to_llvm.c b/src/amd/llvm/ac_nir_to_llvm.c
index d1c333ac73d252004c6a54a003cf9ce3394f77e5..be1c599fbb1825387cb47cfc4237f8c2fa17ee0d 100644 (file)
--- a/src/amd/llvm/ac_nir_to_llvm.c
+++ b/src/amd/llvm/ac_nir_to_llvm.c
@@ -2328,14 +2328,20 @@ static LLVMValueRef visit_load_var(struct ac_nir_context *ctx,
                break;
        case nir_var_mem_global:  {
                LLVMValueRef address = get_src(ctx, instr->src[0]);
+               LLVMTypeRef result_type = get_def_type(ctx, &instr->dest.ssa);
                unsigned explicit_stride = glsl_get_explicit_stride(deref->type);
                unsigned natural_stride = type_scalar_size_bytes(deref->type);
                unsigned stride = explicit_stride ? explicit_stride : natural_stride;
+               int elem_size_bytes = ac_get_elem_bits(&ctx->ac, result_type) / 8;
+               bool split_loads = ctx->ac.chip_class == GFX6 &&
+                                  elem_size_bytes == 1;
 
-               LLVMTypeRef result_type = get_def_type(ctx, &instr->dest.ssa);
-               if (stride != natural_stride) {
-                       LLVMTypeRef ptr_type =  LLVMPointerType(LLVMGetElementType(result_type),
-                                                               LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
+               if (stride != natural_stride || split_loads) {
+                       if (LLVMGetTypeKind(result_type) == LLVMVectorTypeKind)
+                               result_type = LLVMGetElementType(result_type);
+
+                       LLVMTypeRef ptr_type = LLVMPointerType(result_type,
+                                                              LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
                        address = LLVMBuildBitCast(ctx->ac.builder, address, ptr_type , "");
 
                        for (unsigned i = 0; i < instr->dest.ssa.num_components; ++i) {
@@ -2489,23 +2495,30 @@ visit_store_var(struct ac_nir_context *ctx,
                unsigned explicit_stride = glsl_get_explicit_stride(deref->type);
                unsigned natural_stride = type_scalar_size_bytes(deref->type);
                unsigned stride = explicit_stride ? explicit_stride : natural_stride;
+               int elem_size_bytes = ac_get_elem_bits(&ctx->ac, LLVMTypeOf(val)) / 8;
+               bool split_stores = ctx->ac.chip_class == GFX6 &&
+                                   elem_size_bytes == 1;
 
                LLVMTypeRef ptr_type =  LLVMPointerType(LLVMTypeOf(val),
                                                        LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
                address = LLVMBuildBitCast(ctx->ac.builder, address, ptr_type , "");
 
                if (writemask == (1u << ac_get_llvm_num_components(val)) - 1 &&
-                   stride == natural_stride) {
-                       LLVMTypeRef ptr_type =  LLVMPointerType(LLVMTypeOf(val),
-                                                               LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
+                   stride == natural_stride && !split_stores) {
+                       LLVMTypeRef ptr_type = LLVMPointerType(LLVMTypeOf(val),
+                                                              LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
                        address = LLVMBuildBitCast(ctx->ac.builder, address, ptr_type , "");
 
                        val = LLVMBuildBitCast(ctx->ac.builder, val,
                                               LLVMGetElementType(LLVMTypeOf(address)), "");
                        LLVMBuildStore(ctx->ac.builder, val, address);
                } else {
-                       LLVMTypeRef ptr_type =  LLVMPointerType(LLVMGetElementType(LLVMTypeOf(val)),
-                                                               LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
+                       LLVMTypeRef val_type = LLVMTypeOf(val);
+                       if (LLVMGetTypeKind(LLVMTypeOf(val)) == LLVMVectorTypeKind)
+                               val_type = LLVMGetElementType(val_type);
+
+                       LLVMTypeRef ptr_type = LLVMPointerType(val_type,
+                                                              LLVMGetPointerAddressSpace(LLVMTypeOf(address)));
                        address = LLVMBuildBitCast(ctx->ac.builder, address, ptr_type , "");
                        for (unsigned chan = 0; chan < 4; chan++) {
                                if (!(writemask & (1 << chan)))