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, 3 insertions, 2 deletions

diff --git a/src/intel/vulkan/anv_pipeline.c b/src/intel/vulkan/anv_pipeline.c
index 230f2f593e2..16dcda9fc61 100644
--- a/src/intel/vulkan/anv_pipeline.c
+++ b/src/intel/vulkan/anv_pipeline.c
@@ -173,8 +173,6 @@ anv_shader_compile_to_nir(struct anv_pipeline *pipeline,
       nir_print_shader(nir, stderr);
    }
 
-   NIR_PASS_V(nir, nir_lower_deref_instrs, ~0);
-
    /* We have to lower away local constant initializers right before we
     * inline functions.  That way they get properly initialized at the top
     * of the function and not at the top of its caller.
@@ -182,6 +180,7 @@ anv_shader_compile_to_nir(struct anv_pipeline *pipeline,
    NIR_PASS_V(nir, nir_lower_constant_initializers, nir_var_local);
    NIR_PASS_V(nir, nir_lower_returns);
    NIR_PASS_V(nir, nir_inline_functions);
+   NIR_PASS_V(nir, nir_copy_prop);
 
    /* Pick off the single entrypoint that we want */
    foreach_list_typed_safe(nir_function, func, node, &nir->functions) {
@@ -191,6 +190,8 @@ anv_shader_compile_to_nir(struct anv_pipeline *pipeline,
    assert(exec_list_length(&nir->functions) == 1);
    entry_point->name = ralloc_strdup(entry_point, "main");
 
+   NIR_PASS_V(nir, nir_lower_deref_instrs, ~0);
+
    /* Now that we've deleted all but the main function, we can go ahead and
     * lower the rest of the constant initializers.  We do this here so that
     * nir_remove_dead_variables and split_per_member_structs below see the