[Mesa-dev] [PATCH 04/14] radeonsi: Add buffer load functions.

[Bas Nieuwenhuizen]

On Tue, May 10, 2016 at 6:13 PM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> On 10.05.2016 05:52, Bas Nieuwenhuizen wrote:
>>
>> Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
>> ---
>>   src/gallium/drivers/radeonsi/si_shader.c | 81
>> ++++++++++++++++++++++++++++++++
>>   1 file changed, 81 insertions(+)
>>
>> diff --git a/src/gallium/drivers/radeonsi/si_shader.c
>> b/src/gallium/drivers/radeonsi/si_shader.c
>> index 5897149..d3df4d6 100644
>> --- a/src/gallium/drivers/radeonsi/si_shader.c
>> +++ b/src/gallium/drivers/radeonsi/si_shader.c
>> @@ -733,6 +733,87 @@ static void build_tbuffer_store_dwords(struct
>> si_shader_context *ctx,
>>                             V_008F0C_BUF_NUM_FORMAT_UINT, 1, 0, 1, 1, 0);
>>   }
>>
>> +static LLVMValueRef build_buffer_load(struct si_shader_context *ctx,
>> +                               LLVMValueRef rsrc,
>> +                               int num_channels,
>> +                               LLVMValueRef vindex,
>> +                               LLVMValueRef voffset,
>> +                               LLVMValueRef soffset,
>> +                               unsigned inst_offset,
>> +                               unsigned glc,
>> +                               unsigned slc)
>> +{
>> +       struct gallivm_state *gallivm = &ctx->radeon_bld.gallivm;
>> +       LLVMValueRef args[] = {
>> +               LLVMBuildBitCast(gallivm->builder, rsrc, ctx->v16i8, ""),
>> +               voffset ? voffset : vindex,
>> +               soffset,
>> +               LLVMConstInt(ctx->i32, inst_offset, 0),
>> +               LLVMConstInt(ctx->i32, voffset ? 1 : 0, 0), // offen
>> +               LLVMConstInt(ctx->i32, vindex ? 1 : 0, 0), //idxen
>> +               LLVMConstInt(ctx->i32, glc, 0),
>> +               LLVMConstInt(ctx->i32, slc, 0),
>> +               LLVMConstInt(ctx->i32, 0, 0), // TFE
>> +       };
>> +
>> +       unsigned func = CLAMP(num_channels, 1, 3) - 1;
>> +       LLVMTypeRef types[] = {ctx->i32, LLVMVectorType(ctx->i32, 2),
>> ctx->v4i32};
>> +       const char *type_names[] = {"i32", "v2i32", "v4i32"};
>> +       const char *arg_type = "i32";
>> +
>> +       if (voffset && vindex) {
>> +               LLVMValueRef vaddr[] = {vindex, voffset};
>> +
>> +               arg_type = "v2i32";
>> +               args[1] = lp_build_gather_values(gallivm, vaddr, 2);
>> +       }
>> +
>> +       char name[256];
>> +       snprintf(name, sizeof(name), "llvm.SI.buffer.load.dword.%s.%s",
>> +                type_names[func], arg_type);
>
>
> We're generally trying to get away from the llvm.SI.* intrinsics and use the
> llvm.amdgcn.* intrinsic instead - in this case llvm.amdgcn.buffer.load.

The llvm.amdgcn.buffer.load doesn't allow specifiying VGPR + SGPR +
immediate offset separately though as far as I can see. Furthermore I
was trying to avoid a LLVM 3.9 dependency, although I can solve that
with if based on LLVM version.

- Bas

>
> Nicolai
>
>
>> +
>> +       return lp_build_intrinsic(gallivm->builder, name, types[func],
>> args,
>> +                                 ARRAY_SIZE(args), LLVMReadOnlyAttribute
>> |
>> +
>> LLVMNoUnwindAttribute);
>> +}
>> +
>> +static LLVMValueRef buffer_load(struct lp_build_tgsi_context *bld_base,
>> +                                enum tgsi_opcode_type type, unsigned
>> swizzle,
>> +                                LLVMValueRef buffer, LLVMValueRef offset,
>> +                                LLVMValueRef base)
>> +{
>> +       struct si_shader_context *ctx = si_shader_context(bld_base);
>> +       struct gallivm_state *gallivm = bld_base->base.gallivm;
>> +       LLVMValueRef value, value2;
>> +       LLVMTypeRef llvm_type = tgsi2llvmtype(bld_base, type);
>> +       LLVMTypeRef vec_type = LLVMVectorType(llvm_type, 4);
>> +
>> +       if (swizzle == ~0) {
>> +
>> +               value = build_buffer_load(ctx, buffer, 4, NULL, base,
>> offset,
>> +                                         0, 1, 0);
>> +
>> +               return LLVMBuildBitCast(gallivm->builder, value, vec_type,
>> "");
>> +       }
>> +
>> +       if (type != TGSI_TYPE_DOUBLE) {
>> +               value = build_buffer_load(ctx, buffer, 4, NULL, base,
>> offset,
>> +                                         0, 1, 0);
>> +
>> +               value = LLVMBuildBitCast(gallivm->builder, value,
>> vec_type, "");
>> +               return LLVMBuildExtractElement(gallivm->builder, value,
>> +                                   lp_build_const_int32(gallivm,
>> swizzle), "");
>> +       }
>> +
>> +       value = build_buffer_load(ctx, buffer, 1, NULL, base, offset,
>> +                                 swizzle * 4, 1, 0);
>> +
>> +       value2 = build_buffer_load(ctx, buffer, 1, NULL, base, offset,
>> +                                  swizzle * 4 + 4, 1, 0);
>> +
>> +       return radeon_llvm_emit_fetch_double(bld_base, value, value2);
>> +}
>> +
>>   /**
>>    * Load from LDS.
>>    *
>>
>