[Mesa-dev] [PATCH 06/14] nir: handle different bit sizes when constant folding

Iago Toral itoral at igalia.com
Tue Mar 15 09:53:41 UTC 2016


On Mon, 2016-03-14 at 16:48 -0700, Jason Ekstrand wrote:
> 
> 
> On Mon, Mar 7, 2016 at 12:46 AM, Samuel Iglesias Gonsálvez
> <siglesias at igalia.com> wrote:
>         From: Connor Abbott <connor.w.abbott at intel.com>
>         
>         v2: Use the bit-size information from the opcode information
>         if defined (Iago)
>         
>         Signed-off-by: Iago Toral Quiroga <itoral at igalia.com>
>         
>         FIXME: This should be squashed into the previous commit so we
>         don't break
>         the build. The break happens because the python script that
>         generates the
>         constant folding pass does not know how to handle the sized
>         types introduced
>         by the previous commit until this patch, so it ends up
>         generating code with
>         invalid types. Keep it separated for review purposes.
>         ---
>          src/compiler/nir/nir_constant_expressions.h  |   2 +-
>          src/compiler/nir/nir_constant_expressions.py | 246
>         +++++++++++++++++----------
>          src/compiler/nir/nir_opt_constant_folding.c  |  24 ++-
>          3 files changed, 182 insertions(+), 90 deletions(-)
>         
>         diff --git a/src/compiler/nir/nir_constant_expressions.h
>         b/src/compiler/nir/nir_constant_expressions.h
>         index 97997f2..201f278 100644
>         --- a/src/compiler/nir/nir_constant_expressions.h
>         +++ b/src/compiler/nir/nir_constant_expressions.h
>         @@ -28,4 +28,4 @@
>          #include "nir.h"
>         
>          nir_const_value nir_eval_const_opcode(nir_op op, unsigned
>         num_components,
>         -                                      nir_const_value *src);
>         +                                      unsigned bit_size,
>         nir_const_value *src);
>         diff --git a/src/compiler/nir/nir_constant_expressions.py
>         b/src/compiler/nir/nir_constant_expressions.py
>         index 32784f6..972d281 100644
>         --- a/src/compiler/nir/nir_constant_expressions.py
>         +++ b/src/compiler/nir/nir_constant_expressions.py
>         @@ -1,4 +1,43 @@
>          #! /usr/bin/python2
>         +
>         +def type_has_size(type_):
>         +    return type_[-1:].isdigit()
>         +
>         +def type_sizes(type_):
>         +    if type_.endswith("8"):
>         +        return [8]
>         +    elif type_.endswith("16"):
>         +        return [16]
>         +    elif type_.endswith("32"):
>         +        return [32]
>         +    elif type_.endswith("64"):
>         +        return [64]
>         +    else:
>         +        return [32, 64]
>         +
>         +def type_add_size(type_, size):
>         +    if type_has_size(type_):
>         +        return type_
>         +    return type_ + str(size)
>         +
>         +def get_const_field(type_):
>         +    if type_ == "int32":
>         +        return "i"
>         +    if type_ == "uint32":
>         +        return "u"
>         +    if type_ == "int64":
>         +        return "l"
>         +    if type_ == "uint64":
>         +        return "ul"
>         +    if type_ == "bool32":
>         +        return "b"
>         +    if type_ == "float32":
>         +        return "f"
>         +    if type_ == "float64":
>         +        return "d"
>         +    raise Exception(str(type_))
>         +    assert(0)
>         +
>          template = """\
>          /*
>           * Copyright (C) 2014 Intel Corporation
>         @@ -205,110 +244,140 @@ unpack_half_1x16(uint16_t u)
>          }
>         
>          /* Some typed vector structures to make things like src0.y
>         work */
>         -% for type in ["float", "int", "uint", "bool"]:
>         -struct ${type}_vec {
>         -   ${type} x;
>         -   ${type} y;
>         -   ${type} z;
>         -   ${type} w;
>         +typedef float float32_t;
>         +typedef double float64_t;
>         +typedef bool bool32_t;
>         +% for type in ["float", "int", "uint"]:
>         +% for width in [32, 64]:
>         +struct ${type}${width}_vec {
>         +   ${type}${width}_t x;
>         +   ${type}${width}_t y;
>         +   ${type}${width}_t z;
>         +   ${type}${width}_t w;
>          };
>          % endfor
>         +% endfor
>         +
>         +struct bool32_vec {
>         +    bool x;
>         +    bool y;
>         +    bool z;
>         +    bool w;
>         +};
>         
>          % for name, op in sorted(opcodes.iteritems()):
>          static nir_const_value
>         -evaluate_${name}(unsigned num_components, nir_const_value
>         *_src)
>         +evaluate_${name}(unsigned num_components, unsigned bit_size,
>         +                 nir_const_value *_src)
>          {
>             nir_const_value _dst_val = { { {0, 0, 0, 0} } };
>         
>         -   ## For each non-per-component input, create a variable
>         srcN that
>         -   ## contains x, y, z, and w elements which are filled in
>         with the
>         -   ## appropriately-typed values.
>         -   % for j in range(op.num_inputs):
>         -      % if op.input_sizes[j] == 0:
>         -         <% continue %>
>         -      % elif "src" + str(j) not in op.const_expr:
>         -         ## Avoid unused variable warnings
>         -         <% continue %>
>         -      %endif
>         -
>         -      struct ${op.input_types[j]}_vec src${j} = {
>         -      % for k in range(op.input_sizes[j]):
>         -         % if op.input_types[j] == "bool":
>         -            _src[${j}].u[${k}] != 0,
>         -         % else:
>         -            _src[${j}].${op.input_types[j][:1]}[${k}],
>         -         % endif
>         -      % endfor
>         -      };
>         -   % endfor
>         +   switch (bit_size) {
>         +   % for bit_size in [32, 64]:
>         +   case ${bit_size}: {
>         +      <%
>         +      output_type = type_add_size(op.output_type, bit_size)
>         +      input_types = [type_add_size(type_, bit_size) for type_
>         in op.input_types]
>         +      %>
>         +
>         +      ## For each non-per-component input, create a variable
>         srcN that
>         +      ## contains x, y, z, and w elements which are filled in
>         with the
>         +      ## appropriately-typed values.
>         +      % for j in range(op.num_inputs):
>         +         % if op.input_sizes[j] == 0:
>         +            <% continue %>
>         +         % elif "src" + str(j) not in op.const_expr:
>         +            ## Avoid unused variable warnings
>         +            <% continue %>
>         +         %endif
>         
>         -   % if op.output_size == 0:
>         -      ## For per-component instructions, we need to iterate
>         over the
>         -      ## components and apply the constant expression one
>         component
>         -      ## at a time.
>         -      for (unsigned _i = 0; _i < num_components; _i++) {
>         -         ## For each per-component input, create a variable
>         srcN that
>         -         ## contains the value of the current (_i'th)
>         component.
>         -         % for j in range(op.num_inputs):
>         -            % if op.input_sizes[j] != 0:
>         -               <% continue %>
>         -            % elif "src" + str(j) not in op.const_expr:
>         -               ## Avoid unused variable warnings
>         -               <% continue %>
>         -            % elif op.input_types[j] == "bool":
>         -               bool src${j} = _src[${j}].u[_i] != 0;
>         +         struct ${input_types[j]}_vec src${j} = {
>         +         % for k in range(op.input_sizes[j]):
>         +            % if input_types[j] == "bool32":
>         +               _src[${j}].u[${k}] != 0,
>                      % else:
>         -               ${op.input_types[j]} src${j} =
>         _src[${j}].${op.input_types[j][:1]}[_i];
>         +
>          _src[${j}].${get_const_field(input_types[j])}[${k}],
>                      % endif
>                   % endfor
>         +         };
>         +      % endfor
>         +
>         +      % if op.output_size == 0:
>         +         ## For per-component instructions, we need to
>         iterate over the
>         +         ## components and apply the constant expression one
>         component
>         +         ## at a time.
>         +         for (unsigned _i = 0; _i < num_components; _i++) {
>         +            ## For each per-component input, create a
>         variable srcN that
>         +            ## contains the value of the current (_i'th)
>         component.
>         +            % for j in range(op.num_inputs):
>         +               % if op.input_sizes[j] != 0:
>         +                  <% continue %>
>         +               % elif "src" + str(j) not in op.const_expr:
>         +                  ## Avoid unused variable warnings
>         +                  <% continue %>
>         +               % elif input_types[j] == "bool32":
>         +                  bool src${j} = _src[${j}].u[_i] != 0;
>         +               % else:
>         +                  ${input_types[j]}_t src${j} =
>         +
>          _src[${j}].${get_const_field(input_types[j])}[_i];
>         +               % endif
>         +            % endfor
>         +
>         +            ## Create an appropriately-typed variable dst and
>         assign the
>         +            ## result of the const_expr to it.  If const_expr
>         already contains
>         +            ## writes to dst, just include const_expr
>         directly.
>         +            % if "dst" in op.const_expr:
>         +               ${output_type}_t dst;
>         +               ${op.const_expr}
>         +            % else:
>         +               ${output_type}_t dst = ${op.const_expr};
>         +            % endif
>         +
>         +            ## Store the current component of the actual
>         destination to the
>         +            ## value of dst.
>         +            % if output_type == "bool32":
>         +               ## Sanitize the C value to a proper NIR bool
>         +               _dst_val.u[_i] = dst ? NIR_TRUE : NIR_FALSE;
>         +            % else:
>         +               _dst_val.${get_const_field(output_type)}[_i] =
>         dst;
>         +            % endif
>         +         }
>         +      % else:
>         +         ## In the non-per-component case, create a struct
>         dst with
>         +         ## appropriately-typed elements x, y, z, and w and
>         assign the result
>         +         ## of the const_expr to all components of dst, or
>         include the
>         +         ## const_expr directly if it writes to dst already.
>         +         struct ${output_type}_vec dst;
>         
>         -         ## Create an appropriately-typed variable dst and
>         assign the
>         -         ## result of the const_expr to it.  If const_expr
>         already contains
>         -         ## writes to dst, just include const_expr directly.
>                   % if "dst" in op.const_expr:
>         -            ${op.output_type} dst;
>                      ${op.const_expr}
>                   % else:
>         -            ${op.output_type} dst = ${op.const_expr};
>         +            ## Splat the value to all components.  This way
>         expressions which
>         +            ## write the same value to all components don't
>         need to explicitly
>         +            ## write to dest.  One such example is fnoise
>         which has a
>         +            ## const_expr of 0.0f.
>         +            dst.x = dst.y = dst.z = dst.w = ${op.const_expr};
>                   % endif
>         
>         -         ## Store the current component of the actual
>         destination to the
>         -         ## value of dst.
>         -         % if op.output_type == "bool":
>         -            ## Sanitize the C value to a proper NIR bool
>         -            _dst_val.u[_i] = dst ? NIR_TRUE : NIR_FALSE;
>         -         % else:
>         -            _dst_val.${op.output_type[:1]}[_i] = dst;
>         -         % endif
>         -      }
>         -   % else:
>         -      ## In the non-per-component case, create a struct dst
>         with
>         -      ## appropriately-typed elements x, y, z, and w and
>         assign the result
>         -      ## of the const_expr to all components of dst, or
>         include the
>         -      ## const_expr directly if it writes to dst already.
>         -      struct ${op.output_type}_vec dst;
>         -
>         -      % if "dst" in op.const_expr:
>         -         ${op.const_expr}
>         -      % else:
>         -         ## Splat the value to all components.  This way
>         expressions which
>         -         ## write the same value to all components don't need
>         to explicitly
>         -         ## write to dest.  One such example is fnoise which
>         has a
>         -         ## const_expr of 0.0f.
>         -         dst.x = dst.y = dst.z = dst.w = ${op.const_expr};
>         +         ## For each component in the destination, copy the
>         value of dst to
>         +         ## the actual destination.
>         +         % for k in range(op.output_size):
>         +            % if output_type == "bool32":
>         +               ## Sanitize the C value to a proper NIR bool
>         +               _dst_val.u[${k}] = dst.${"xyzw"[k]} ?
>         NIR_TRUE : NIR_FALSE;
>         +            % else:
>         +               _dst_val.${get_const_field(output_type)}[${k}]
>         = dst.${"xyzw"[k]};
>         +            % endif
>         +         % endfor
>                % endif
>         
>         -      ## For each component in the destination, copy the
>         value of dst to
>         -      ## the actual destination.
>         -      % for k in range(op.output_size):
>         -         % if op.output_type == "bool":
>         -            ## Sanitize the C value to a proper NIR bool
>         -            _dst_val.u[${k}] = dst.${"xyzw"[k]} ? NIR_TRUE :
>         NIR_FALSE;
>         -         % else:
>         -            _dst_val.${op.output_type[:1]}[${k}] =
>         dst.${"xyzw"[k]};
>         -         % endif
>         -      % endfor
>         -   % endif
>         +      break;
>         +   }
>         +   % endfor
>         +
>         +   default:
>         +      unreachable("unknown bit width");
>         +   }
>         
>             return _dst_val;
>          }
>         @@ -316,12 +385,12 @@ evaluate_${name}(unsigned
>         num_components, nir_const_value *_src)
>         
>          nir_const_value
>          nir_eval_const_opcode(nir_op op, unsigned num_components,
>         -                      nir_const_value *src)
>         +                      unsigned bit_width, nir_const_value
>         *src)
>          {
>             switch (op) {
>          % for name in sorted(opcodes.iterkeys()):
>             case nir_op_${name}: {
>         -      return evaluate_${name}(num_components, src);
>         +      return evaluate_${name}(num_components, bit_width,
>         src);
>                break;
>             }
>          % endfor
>         @@ -333,4 +402,7 @@ nir_eval_const_opcode(nir_op op, unsigned
>         num_components,
>          from nir_opcodes import opcodes
>          from mako.template import Template
>         
>         -print Template(template).render(opcodes=opcodes)
>         +print Template(template).render(opcodes=opcodes,
>         type_sizes=type_sizes,
>         +                                type_has_size=type_has_size,
>         +                                type_add_size=type_add_size,
>         +
>         get_const_field=get_const_field)
>         diff --git a/src/compiler/nir/nir_opt_constant_folding.c
>         b/src/compiler/nir/nir_opt_constant_folding.c
>         index 04876a4..29905a0 100644
>         --- a/src/compiler/nir/nir_opt_constant_folding.c
>         +++ b/src/compiler/nir/nir_opt_constant_folding.c
>         @@ -46,10 +46,23 @@ constant_fold_alu_instr(nir_alu_instr
>         *instr, void *mem_ctx)
>             if (!instr->dest.dest.is_ssa)
>                return false;
>         
>         +   unsigned bit_size = 0;
>         +   if (!(nir_op_infos[instr->op].output_type &
>         NIR_ALU_TYPE_SIZE_MASK))
>         +      bit_size = instr->dest.dest.ssa.bit_size;
>         +   else
>         +      bit_size = nir_op_infos[instr->op].output_type &
>         NIR_ALU_TYPE_SIZE_MASK;
> 
> 
> This isn't right.  We need to look at all the unsized types and try to
> pull it from one of those.  We shouldn't fall back to grabbing from
> the sized type.

Ok, so you don't like that in the case that the alu operation has a
sized destination we grab the bit-size from the opcode definition? I am
not sure I see the problem with that... isn't the opcode mandating a
specific bit-size in that case? How can the bit-size we want be
different from that?

>  
>         +
>             for (unsigned i = 0; i <
>         nir_op_infos[instr->op].num_inputs; i++) {
>                if (!instr->src[i].src.is_ssa)
>                   return false;
>         
>         +      if (bit_size == 0) {
>         +         if (!(nir_op_infos[instr->op].input_sizes[i] &
>         NIR_ALU_TYPE_SIZE_MASK))
>         +            bit_size = instr->src[i].src.ssa->bit_size;
>         +         else
>         +            bit_size = nir_op_infos[instr->op].input_sizes[i]
>         & NIR_ALU_TYPE_SIZE_MASK;
> 
> 
> Same here.  If they don't have any unsized sources or destinations to
> grab from, we should let bit_size be zero.

But if we have an opcode with all sized 64-bit types then...

> Also, if we have multiple sources with the same unsized type, we
> should assert that the sizes match.
> 
>  
>         +      }
>         +
>                nir_instr *src_instr =
>         instr->src[i].src.ssa->parent_instr;
>         
>                if (src_instr->type != nir_instr_type_load_const)
>         @@ -58,24 +71,31 @@ constant_fold_alu_instr(nir_alu_instr
>         *instr, void *mem_ctx)
>         
>                for (unsigned j = 0; j <
>         nir_ssa_alu_instr_src_components(instr, i);
>                     j++) {
>         -         src[i].u[j] =
>         load_const->value.u[instr->src[i].swizzle[j]];
>         +         if (load_const->def.bit_size == 64)
>         +            src[i].ul[j] =
>         load_const->value.ul[instr->src[i].swizzle[j]];
>         +         else
>         +            src[i].u[j] =
>         load_const->value.u[instr->src[i].swizzle[j]];
>                }
>         
>                /* We shouldn't have any source modifiers in the
>         optimization loop. */
>                assert(!instr->src[i].abs && !instr->src[i].negate);
>             }
>         
>         +   if (bit_size == 0)
>         +      bit_size = 32;

... this default to 32 here would not be correct any more. If at this
point the bit-size is 0 (meaning that all inputs and output are sized)
then we should take the bit-size from the opcode's output type, which is
known to be sized, right?

> 
> Then it'll get set here.
> 
>  
>         +
>             /* We shouldn't have any saturate modifiers in the
>         optimization loop. */
>             assert(!instr->dest.saturate);
>         
>             nir_const_value dest =
>                nir_eval_const_opcode(instr->op,
>         instr->dest.dest.ssa.num_components,
>         -                            src);
>         +                            bit_size, src);
>         
>             nir_load_const_instr *new_instr =
>                nir_load_const_instr_create(mem_ctx,
>         
>          instr->dest.dest.ssa.num_components);
>         
>         +   new_instr->def.bit_size = instr->dest.dest.ssa.bit_size;
>             new_instr->value = dest;
>         
>             nir_instr_insert_before(&instr->instr, &new_instr->instr);
>         --
>         2.7.0
>         
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> 
> 
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