nir,spirv: Rework function calls

This commit completely reworks function calls in NIR.  Instead of having
a set of variables for the parameters and return value, nir_call_instr
now has simply has a number of sources which get mapped to load_param
intrinsics inside the functions.  It's up to the client API to build an
ABI on top of that.  In SPIR-V, out parameters are handled by passing
the result of a deref through as an SSA value and storing to it.

This virtue of this approach can be seen by how much it allows us to
delete from core NIR.  In particular, nir_inline_functions gets halved
and goes from a fairly difficult pass to understand in detail to almost
trivial.  It also simplifies spirv_to_nir somewhat because NIR functions
never were a good fit for SPIR-V.

Unfortunately, there is no good way to do this without a mega-commit.
Core NIR and SPIR-V have to be changed at the same time.  This also
requires changes to anv and radv because nir_inline_functions couldn't
handle deref instructions before this change and can't work without them
after this change.

Acked-by: Rob Clark <[email protected]>
Acked-by: Bas Nieuwenhuizen <[email protected]>
Acked-by: Dave Airlie <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 12 insertions, 23 deletions

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index 9e4aa1df5bd..6642977fa3e 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -99,7 +99,6 @@ typedef enum {
    nir_var_uniform         = (1 << 4),
    nir_var_shader_storage  = (1 << 5),
    nir_var_system_value    = (1 << 6),
-   nir_var_param           = (1 << 7),
    nir_var_shared          = (1 << 8),
    nir_var_all             = ~0,
 } nir_variable_mode;
@@ -392,7 +391,7 @@ typedef struct nir_variable {
 static inline bool
 nir_variable_is_global(const nir_variable *var)
 {
-   return var->data.mode != nir_var_local && var->data.mode != nir_var_param;
+   return var->data.mode != nir_var_local;
 }
 
 typedef struct nir_register {
@@ -1052,11 +1051,10 @@ nir_deref_instr_to_deref(nir_deref_instr *instr, void *mem_ctx);
 typedef struct {
    nir_instr instr;
 
-   unsigned num_params;
-   nir_deref_var **params;
-   nir_deref_var *return_deref;
-
    struct nir_function *callee;
+
+   unsigned num_params;
+   nir_src params[];
 } nir_call_instr;
 
 #include "nir_intrinsics.h"
@@ -1200,6 +1198,11 @@ typedef enum {
     */
    NIR_INTRINSIC_CLUSTER_SIZE = 11,
 
+   /**
+    * Parameter index for a load_param intrinsic
+    */
+   NIR_INTRINSIC_PARAM_IDX = 12,
+
    NIR_INTRINSIC_NUM_INDEX_FLAGS,
 
 } nir_intrinsic_index_flag;
@@ -1292,6 +1295,7 @@ INTRINSIC_IDX_ACCESSORS(component, COMPONENT, unsigned)
 INTRINSIC_IDX_ACCESSORS(interp_mode, INTERP_MODE, unsigned)
 INTRINSIC_IDX_ACCESSORS(reduction_op, REDUCTION_OP, unsigned)
 INTRINSIC_IDX_ACCESSORS(cluster_size, CLUSTER_SIZE, unsigned)
+INTRINSIC_IDX_ACCESSORS(param_idx, PARAM_IDX, unsigned)
 
 /**
  * \group texture information
@@ -1847,13 +1851,6 @@ typedef struct {
    /** list for all local variables in the function */
    struct exec_list locals;
 
-   /** array of variables used as parameters */
-   unsigned num_params;
-   nir_variable **params;
-
-   /** variable used to hold the result of the function */
-   nir_variable *return_var;
-
    /** list of local registers in the function */
    struct exec_list registers;
 
@@ -1964,15 +1961,9 @@ nir_loop_last_block(nir_loop *loop)
    return nir_cf_node_as_block(exec_node_data(nir_cf_node, tail, node));
 }
 
-typedef enum {
-   nir_parameter_in,
-   nir_parameter_out,
-   nir_parameter_inout,
-} nir_parameter_type;
-
 typedef struct {
-   nir_parameter_type param_type;
-   const struct glsl_type *type;
+   uint8_t num_components;
+   uint8_t bit_size;
 } nir_parameter;
 
 typedef struct nir_function {
@@ -1983,7 +1974,6 @@ typedef struct nir_function {
 
    unsigned num_params;
    nir_parameter *params;
-   const struct glsl_type *return_type;
 
    /** The implementation of this function.
     *
@@ -2164,7 +2154,6 @@ nir_shader_get_entrypoint(nir_shader *shader)
    assert(exec_list_length(&shader->functions) == 1);
    struct exec_node *func_node = exec_list_get_head(&shader->functions);
    nir_function *func = exec_node_data(nir_function, func_node, node);
-   assert(func->return_type == glsl_void_type());
    assert(func->num_params == 0);
    assert(func->impl);
    return func->impl;