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nir/deref: fix struct wrapper casts. (v3) 

llvm/spir-v spits out some struct a { struct b {} }, but it
doesn't deref, it casts (struct a) to (struct b), reconstruct
struct derefs instead of casts for these.

v2: use ssa_def_rewrite uses, rework the type restrictions (Jason)
v3: squish more stuff into one function, drop unused temp (Jason)

Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Dave Airlie 2019-03-08 13:09:05 +10:00
parent 8e0469f629
commit b779baa9bf
1 changed files with 36 additions and 2 deletions
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38
src/compiler/nir/nir_deref.c
View File

@ -697,11 +697,45 @@ opt_remove_cast_cast(nir_deref_instr *cast)
return true;
}
/**
* Is this casting a struct to a contained struct.
* struct a { struct b field0 };
* ssa_5 is structa;
* deref_cast (structb *)ssa_5 (function_temp structb);
* converts to
* deref_struct &ssa_5->field0 (function_temp structb);
* This allows subsequent copy propagation to work.
*/
static bool
opt_deref_cast(nir_deref_instr *cast)
opt_replace_struct_wrapper_cast(nir_builder *b, nir_deref_instr *cast)
{
nir_deref_instr *parent = nir_src_as_deref(cast->parent);
if (!parent)
return false;
if (!glsl_type_is_struct(parent->type))
return false;
if (glsl_get_struct_field_offset(parent->type, 0) != 0)
return false;
if (cast->type != glsl_get_struct_field(parent->type, 0))
return false;
nir_deref_instr *replace = nir_build_deref_struct(b, parent, 0);
nir_ssa_def_rewrite_uses(&cast->dest.ssa, nir_src_for_ssa(&replace->dest.ssa));
nir_deref_instr_remove_if_unused(cast);
return true;
}
static bool
opt_deref_cast(nir_builder *b, nir_deref_instr *cast)
{
bool progress;
if (opt_replace_struct_wrapper_cast(b, cast))
return true;
progress = opt_remove_cast_cast(cast);
if (!is_trivial_deref_cast(cast))
return progress;
@ -798,7 +832,7 @@ nir_opt_deref_impl(nir_function_impl *impl)
break;
case nir_deref_type_cast:
if (opt_deref_cast(deref))
if (opt_deref_cast(&b, deref))
progress = true;
break;