/*
* Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "vtn_private.h"
#include "spirv_info.h"
#include "nir/nir_vla.h"
#include "util/debug.h"
static struct vtn_block *
vtn_block(struct vtn_builder *b, uint32_t value_id)
{
return vtn_value(b, value_id, vtn_value_type_block)->block;
}
static unsigned
glsl_type_count_function_params(const struct glsl_type *type)
{
if (glsl_type_is_vector_or_scalar(type)) {
return 1;
} else if (glsl_type_is_array_or_matrix(type)) {
return glsl_get_length(type) *
glsl_type_count_function_params(glsl_get_array_element(type));
} else {
assert(glsl_type_is_struct_or_ifc(type));
unsigned count = 0;
unsigned elems = glsl_get_length(type);
for (unsigned i = 0; i < elems; i++) {
const struct glsl_type *elem_type = glsl_get_struct_field(type, i);
count += glsl_type_count_function_params(elem_type);
}
return count;
}
}
static void
glsl_type_add_to_function_params(const struct glsl_type *type,
nir_function *func,
unsigned *param_idx)
{
if (glsl_type_is_vector_or_scalar(type)) {
func->params[(*param_idx)++] = (nir_parameter) {
.num_components = glsl_get_vector_elements(type),
.bit_size = glsl_get_bit_size(type),
};
} else if (glsl_type_is_array_or_matrix(type)) {
unsigned elems = glsl_get_length(type);
const struct glsl_type *elem_type = glsl_get_array_element(type);
for (unsigned i = 0; i < elems; i++)
glsl_type_add_to_function_params(elem_type,func, param_idx);
} else {
assert(glsl_type_is_struct_or_ifc(type));
unsigned elems = glsl_get_length(type);
for (unsigned i = 0; i < elems; i++) {
const struct glsl_type *elem_type = glsl_get_struct_field(type, i);
glsl_type_add_to_function_params(elem_type, func, param_idx);
}
}
}
static void
vtn_ssa_value_add_to_call_params(struct vtn_builder *b,
struct vtn_ssa_value *value,
nir_call_instr *call,
unsigned *param_idx)
{
if (glsl_type_is_vector_or_scalar(value->type)) {
call->params[(*param_idx)++] = nir_src_for_ssa(value->def);
} else {
unsigned elems = glsl_get_length(value->type);
for (unsigned i = 0; i < elems; i++) {
vtn_ssa_value_add_to_call_params(b, value->elems[i],
call, param_idx);
}
}
}
static void
vtn_ssa_value_load_function_param(struct vtn_builder *b,
struct vtn_ssa_value *value,
unsigned *param_idx)
{
if (glsl_type_is_vector_or_scalar(value->type)) {
value->def = nir_load_param(&b->nb, (*param_idx)++);
} else {
unsigned elems = glsl_get_length(value->type);
for (unsigned i = 0; i < elems; i++)
vtn_ssa_value_load_function_param(b, value->elems[i], param_idx);
}
}
void
vtn_handle_function_call(struct vtn_builder *b, SpvOp opcode,
const uint32_t *w, unsigned count)
{
struct vtn_function *vtn_callee =
vtn_value(b, w[3], vtn_value_type_function)->func;
vtn_callee->referenced = true;
nir_call_instr *call = nir_call_instr_create(b->nb.shader,
vtn_callee->nir_func);
unsigned param_idx = 0;
nir_deref_instr *ret_deref = NULL;
struct vtn_type *ret_type = vtn_callee->type->return_type;
if (ret_type->base_type != vtn_base_type_void) {
nir_variable *ret_tmp =
nir_local_variable_create(b->nb.impl,
glsl_get_bare_type(ret_type->type),
"return_tmp");
ret_deref = nir_build_deref_var(&b->nb, ret_tmp);
call->params[param_idx++] = nir_src_for_ssa(&ret_deref->dest.ssa);
}
for (unsigned i = 0; i < vtn_callee->type->length; i++) {
vtn_ssa_value_add_to_call_params(b, vtn_ssa_value(b, w[4 + i]),
call, ¶m_idx);
}
assert(param_idx == call->num_params);
nir_builder_instr_insert(&b->nb, &call->instr);
if (ret_type->base_type == vtn_base_type_void) {
vtn_push_value(b, w[2], vtn_value_type_undef);
} else {
vtn_push_ssa_value(b, w[2], vtn_local_load(b, ret_deref, 0));
}
}
static bool
vtn_cfg_handle_prepass_instruction(struct vtn_builder *b, SpvOp opcode,
const uint32_t *w, unsigned count)
{
switch (opcode) {
case SpvOpFunction: {
vtn_assert(b->func == NULL);
b->func = rzalloc(b, struct vtn_function);
b->func->node.type = vtn_cf_node_type_function;
b->func->node.parent = NULL;
list_inithead(&b->func->body);
b->func->control = w[3];
UNUSED const struct glsl_type *result_type = vtn_get_type(b, w[1])->type;
struct vtn_value *val = vtn_push_value(b, w[2], vtn_value_type_function);
val->func = b->func;
b->func->type = vtn_get_type(b, w[4]);
const struct vtn_type *func_type = b->func->type;
vtn_assert(func_type->return_type->type == result_type);
nir_function *func =
nir_function_create(b->shader, ralloc_strdup(b->shader, val->name));
unsigned num_params = 0;
for (unsigned i = 0; i < func_type->length; i++)
num_params += glsl_type_count_function_params(func_type->params[i]->type);
/* Add one parameter for the function return value */
if (func_type->return_type->base_type != vtn_base_type_void)
num_params++;
func->num_params = num_params;
func->params = ralloc_array(b->shader, nir_parameter, num_params);
unsigned idx = 0;
if (func_type->return_type->base_type != vtn_base_type_void) {
nir_address_format addr_format =
vtn_mode_to_address_format(b, vtn_variable_mode_function);
/* The return value is a regular pointer */
func->params[idx++] = (nir_parameter) {
.num_components = nir_address_format_num_components(addr_format),
.bit_size = nir_address_format_bit_size(addr_format),
};
}
for (unsigned i = 0; i < func_type->length; i++)
glsl_type_add_to_function_params(func_type->params[i]->type, func, &idx);
assert(idx == num_params);
b->func->nir_func = func;
/* Set up a nir_function_impl and the builder so we can load arguments
* directly in our OpFunctionParameter handler.
*/
nir_function_impl *impl = nir_function_impl_create(func);
nir_builder_init(&b->nb, impl);
b->nb.cursor = nir_before_cf_list(&impl->body);
b->nb.exact = b->exact;
b->func_param_idx = 0;
/* The return value is the first parameter */
if (func_type->return_type->base_type != vtn_base_type_void)
b->func_param_idx++;
break;
}
case SpvOpFunctionEnd:
b->func->end = w;
if (b->func->start_block == NULL) {
/* In this case, the function didn't have any actual blocks. It's
* just a prototype so delete the function_impl.
*/
b->func->nir_func->impl = NULL;
}
b->func = NULL;
break;
case SpvOpFunctionParameter: {
vtn_assert(b->func_param_idx < b->func->nir_func->num_params);
struct vtn_type *type = vtn_get_type(b, w[1]);
struct vtn_ssa_value *value = vtn_create_ssa_value(b, type->type);
vtn_ssa_value_load_function_param(b, value, &b->func_param_idx);
vtn_push_ssa_value(b, w[2], value);
break;
}
case SpvOpLabel: {
vtn_assert(b->block == NULL);
b->block = rzalloc(b, struct vtn_block);
b->block->node.type = vtn_cf_node_type_block;
b->block->label = w;
vtn_push_value(b, w[1], vtn_value_type_block)->block = b->block;
if (b->func->start_block == NULL) {
/* This is the first block encountered for this function. In this
* case, we set the start block and add it to the list of
* implemented functions that we'll walk later.
*/
b->func->start_block = b->block;
list_addtail(&b->func->node.link, &b->functions);
}
break;
}
case SpvOpSelectionMerge:
case SpvOpLoopMerge:
vtn_assert(b->block && b->block->merge == NULL);
b->block->merge = w;
break;
case SpvOpBranch:
case SpvOpBranchConditional:
case SpvOpSwitch:
case SpvOpKill:
case SpvOpTerminateInvocation:
case SpvOpIgnoreIntersectionKHR:
case SpvOpTerminateRayKHR:
case SpvOpReturn:
case SpvOpReturnValue:
case SpvOpUnreachable:
vtn_assert(b->block && b->block->branch == NULL);
b->block->branch = w;
b->block = NULL;
break;
default:
/* Continue on as per normal */
return true;
}
return true;
}
/* This function performs a depth-first search of the cases and puts them
* in fall-through order.
*/
static void
vtn_order_case(struct vtn_switch *swtch, struct vtn_case *cse)
{
if (cse->visited)
return;
cse->visited = true;
list_del(&cse->node.link);
if (cse->fallthrough) {
vtn_order_case(swtch, cse->fallthrough);
/* If we have a fall-through, place this case right before the case it
* falls through to. This ensures that fallthroughs come one after
* the other. These two can never get separated because that would
* imply something else falling through to the same case. Also, this
* can't break ordering because the DFS ensures that this case is
* visited before anything that falls through to it.
*/
list_addtail(&cse->node.link, &cse->fallthrough->node.link);
} else {
list_add(&cse->node.link, &swtch->cases);
}
}
static void
vtn_switch_order_cases(struct vtn_switch *swtch)
{
struct list_head cases;
list_replace(&swtch->cases, &cases);
list_inithead(&swtch->cases);
while (!list_is_empty(&cases)) {
struct vtn_case *cse =
list_first_entry(&cases, struct vtn_case, node.link);
vtn_order_case(swtch, cse);
}
}
static void
vtn_block_set_merge_cf_node(struct vtn_builder *b, struct vtn_block *block,
struct vtn_cf_node *cf_node)
{
vtn_fail_if(block->merge_cf_node != NULL,
"The merge block declared by a header block cannot be a "
"merge block declared by any other header block.");
block->merge_cf_node = cf_node;
}
#define VTN_DECL_CF_NODE_FIND(_type) \
static inline struct vtn_##_type * \
vtn_cf_node_find_##_type(struct vtn_cf_node *node) \
{ \
while (node && node->type != vtn_cf_node_type_##_type) \
node = node->parent; \
return (struct vtn_##_type *)node; \
}
VTN_DECL_CF_NODE_FIND(if)
VTN_DECL_CF_NODE_FIND(loop)
VTN_DECL_CF_NODE_FIND(case)
VTN_DECL_CF_NODE_FIND(switch)
VTN_DECL_CF_NODE_FIND(function)
static enum vtn_branch_type
vtn_handle_branch(struct vtn_builder *b,
struct vtn_cf_node *cf_parent,
struct vtn_block *target_block)
{
struct vtn_loop *loop = vtn_cf_node_find_loop(cf_parent);
/* Detect a loop back-edge first. That way none of the code below
* accidentally operates on a loop back-edge.
*/
if (loop && target_block == loop->header_block)
return vtn_branch_type_loop_back_edge;
/* Try to detect fall-through */
if (target_block->switch_case) {
/* When it comes to handling switch cases, we can break calls to
* vtn_handle_branch into two cases: calls from within a case construct
* and calls for the jump to each case construct. In the second case,
* cf_parent is the vtn_switch itself and vtn_cf_node_find_case() will
* return the outer switch case in which this switch is contained. It's
* fine if the target block is a switch case from an outer switch as
* long as it is also the switch break for this switch.
*/
struct vtn_case *switch_case = vtn_cf_node_find_case(cf_parent);
/* This doesn't get called for the OpSwitch */
vtn_fail_if(switch_case == NULL,
"A switch case can only be entered through an OpSwitch or "
"falling through from another switch case.");
/* Because block->switch_case is only set on the entry block for a given
* switch case, we only ever get here if we're jumping to the start of a
* switch case. It's possible, however, that a switch case could jump
* to itself via a back-edge. That *should* get caught by the loop
* handling case above but if we have a back edge without a loop merge,
* we could en up here.
*/
vtn_fail_if(target_block->switch_case == switch_case,
"A switch cannot fall-through to itself. Likely, there is "
"a back-edge which is not to a loop header.");
vtn_fail_if(target_block->switch_case->node.parent !=
switch_case->node.parent,
"A switch case fall-through must come from the same "
"OpSwitch construct");
vtn_fail_if(switch_case->fallthrough != NULL &&
switch_case->fallthrough != target_block->switch_case,
"Each case construct can have at most one branch to "
"another case construct");
switch_case->fallthrough = target_block->switch_case;
/* We don't immediately return vtn_branch_type_switch_fallthrough
* because it may also be a loop or switch break for an inner loop or
* switch and that takes precedence.
*/
}
if (loop && target_block == loop->cont_block)
return vtn_branch_type_loop_continue;
/* We walk blocks as a breadth-first search on the control-flow construct
* tree where, when we find a construct, we add the vtn_cf_node for that
* construct and continue iterating at the merge target block (if any).
* Therefore, we want merges whose with parent == cf_parent to be treated
* as regular branches. We only want to consider merges if they break out
* of the current CF construct.
*/
if (target_block->merge_cf_node != NULL &&
target_block->merge_cf_node->parent != cf_parent) {
switch (target_block->merge_cf_node->type) {
case vtn_cf_node_type_if:
for (struct vtn_cf_node *node = cf_parent;
node != target_block->merge_cf_node; node = node->parent) {
vtn_fail_if(node == NULL || node->type != vtn_cf_node_type_if,
"Branching to the merge block of a selection "
"construct can only be used to break out of a "
"selection construct");
struct vtn_if *if_stmt = vtn_cf_node_as_if(node);
/* This should be guaranteed by our iteration */
assert(if_stmt->merge_block != target_block);
vtn_fail_if(if_stmt->merge_block != NULL,
"Branching to the merge block of a selection "
"construct can only be used to break out of the "
"inner most nested selection level");
}
return vtn_branch_type_if_merge;
case vtn_cf_node_type_loop:
vtn_fail_if(target_block->merge_cf_node != &loop->node,
"Loop breaks can only break out of the inner most "
"nested loop level");
return vtn_branch_type_loop_break;
case vtn_cf_node_type_switch: {
struct vtn_switch *swtch = vtn_cf_node_find_switch(cf_parent);
vtn_fail_if(target_block->merge_cf_node != &swtch->node,
"Switch breaks can only break out of the inner most "
"nested switch level");
return vtn_branch_type_switch_break;
}
default:
unreachable("Invalid CF node type for a merge");
}
}
if (target_block->switch_case)
return vtn_branch_type_switch_fallthrough;
return vtn_branch_type_none;
}
struct vtn_cfg_work_item {
struct list_head link;
struct vtn_cf_node *cf_parent;
struct list_head *cf_list;
struct vtn_block *start_block;
};
static void
vtn_add_cfg_work_item(struct vtn_builder *b,
struct list_head *work_list,
struct vtn_cf_node *cf_parent,
struct list_head *cf_list,
struct vtn_block *start_block)
{
struct vtn_cfg_work_item *work = ralloc(b, struct vtn_cfg_work_item);
work->cf_parent = cf_parent;
work->cf_list = cf_list;
work->start_block = start_block;
list_addtail(&work->link, work_list);
}
/* returns the default block */
static void
vtn_parse_switch(struct vtn_builder *b,
struct vtn_switch *swtch,
const uint32_t *branch,
struct list_head *case_list)
{
const uint32_t *branch_end = branch + (branch[0] >> SpvWordCountShift);
struct vtn_value *sel_val = vtn_untyped_value(b, branch[1]);
vtn_fail_if(!sel_val->type ||
sel_val->type->base_type != vtn_base_type_scalar,
"Selector of OpSwitch must have a type of OpTypeInt");
nir_alu_type sel_type =
nir_get_nir_type_for_glsl_type(sel_val->type->type);
vtn_fail_if(nir_alu_type_get_base_type(sel_type) != nir_type_int &&
nir_alu_type_get_base_type(sel_type) != nir_type_uint,
"Selector of OpSwitch must have a type of OpTypeInt");
struct hash_table *block_to_case = _mesa_pointer_hash_table_create(b);
bool is_default = true;
const unsigned bitsize = nir_alu_type_get_type_size(sel_type);
for (const uint32_t *w = branch + 2; w < branch_end;) {
uint64_t literal = 0;
if (!is_default) {
if (bitsize <= 32) {
literal = *(w++);
} else {
assert(bitsize == 64);
literal = vtn_u64_literal(w);
w += 2;
}
}
struct vtn_block *case_block = vtn_block(b, *(w++));
struct hash_entry *case_entry =
_mesa_hash_table_search(block_to_case, case_block);
struct vtn_case *cse;
if (case_entry) {
cse = case_entry->data;
} else {
cse = rzalloc(b, struct vtn_case);
cse->node.type = vtn_cf_node_type_case;
cse->node.parent = swtch ? &swtch->node : NULL;
cse->block = case_block;
list_inithead(&cse->body);
util_dynarray_init(&cse->values, b);
list_addtail(&cse->node.link, case_list);
_mesa_hash_table_insert(block_to_case, case_block, cse);
}
if (is_default) {
cse->is_default = true;
} else {
util_dynarray_append(&cse->values, uint64_t, literal);
}
is_default = false;
}
_mesa_hash_table_destroy(block_to_case, NULL);
}
/* Processes a block and returns the next block to process or NULL if we've
* reached the end of the construct.
*/
static struct vtn_block *
vtn_process_block(struct vtn_builder *b,
struct list_head *work_list,
struct vtn_cf_node *cf_parent,
struct list_head *cf_list,
struct vtn_block *block)
{
if (!list_is_empty(cf_list)) {
/* vtn_process_block() acts like an iterator: it processes the given
* block and then returns the next block to process. For a given
* control-flow construct, vtn_build_cfg() calls vtn_process_block()
* repeatedly until it finally returns NULL. Therefore, we know that
* the only blocks on which vtn_process_block() can be called are either
* the first block in a construct or a block that vtn_process_block()
* returned for the current construct. If cf_list is empty then we know
* that we're processing the first block in the construct and we have to
* add it to the list.
*
* If cf_list is not empty, then it must be the block returned by the
* previous call to vtn_process_block(). We know a priori that
* vtn_process_block only returns either normal branches
* (vtn_branch_type_none) or merge target blocks.
*/
switch (vtn_handle_branch(b, cf_parent, block)) {
case vtn_branch_type_none:
/* For normal branches, we want to process them and add them to the
* current construct. Merge target blocks also look like normal
* branches from the perspective of this construct. See also
* vtn_handle_branch().
*/
break;
case vtn_branch_type_loop_continue:
case vtn_branch_type_switch_fallthrough:
/* The two cases where we can get early exits from a construct that
* are not to that construct's merge target are loop continues and
* switch fall-throughs. In these cases, we need to break out of the
* current construct by returning NULL.
*/
return NULL;
default:
/* The only way we can get here is if something was used as two kinds
* of merges at the same time and that's illegal.
*/
vtn_fail("A block was used as a merge target from two or more "
"structured control-flow constructs");
}
}
/* Once a block has been processed, it is placed into and the list link
* will point to something non-null. If we see a node we've already
* processed here, it either exists in multiple functions or it's an
* invalid back-edge.
*/
if (block->node.parent != NULL) {
vtn_fail_if(vtn_cf_node_find_function(&block->node) !=
vtn_cf_node_find_function(cf_parent),
"A block cannot exist in two functions at the "
"same time");
vtn_fail("Invalid back or cross-edge in the CFG");
}
if (block->merge && (*block->merge & SpvOpCodeMask) == SpvOpLoopMerge &&
block->loop == NULL) {
vtn_fail_if((*block->branch & SpvOpCodeMask) != SpvOpBranch &&
(*block->branch & SpvOpCodeMask) != SpvOpBranchConditional,
"An OpLoopMerge instruction must immediately precede "
"either an OpBranch or OpBranchConditional instruction.");
struct vtn_loop *loop = rzalloc(b, struct vtn_loop);
loop->node.type = vtn_cf_node_type_loop;
loop->node.parent = cf_parent;
list_inithead(&loop->body);
list_inithead(&loop->cont_body);
loop->header_block = block;
loop->break_block = vtn_block(b, block->merge[1]);
loop->cont_block = vtn_block(b, block->merge[2]);
loop->control = block->merge[3];
list_addtail(&loop->node.link, cf_list);
block->loop = loop;
/* Note: The work item for the main loop body will start with the
* current block as its start block. If we weren't careful, we would
* get here again and end up in an infinite loop. This is why we set
* block->loop above and check for it before creating one. This way,
* we only create the loop once and the second iteration that tries to
* handle this loop goes to the cases below and gets handled as a
* regular block.
*/
vtn_add_cfg_work_item(b, work_list, &loop->node,
&loop->body, loop->header_block);
/* For continue targets, SPIR-V guarantees the following:
*
* - the Continue Target must dominate the back-edge block
* - the back-edge block must post dominate the Continue Target
*
* If the header block is the same as the continue target, this
* condition is trivially satisfied and there is no real continue
* section.
*/
if (loop->cont_block != loop->header_block) {
vtn_add_cfg_work_item(b, work_list, &loop->node,
&loop->cont_body, loop->cont_block);
}
vtn_block_set_merge_cf_node(b, loop->break_block, &loop->node);
return loop->break_block;
}
/* Add the block to the CF list */
block->node.parent = cf_parent;
list_addtail(&block->node.link, cf_list);
switch (*block->branch & SpvOpCodeMask) {
case SpvOpBranch: {
struct vtn_block *branch_block = vtn_block(b, block->branch[1]);
block->branch_type = vtn_handle_branch(b, cf_parent, branch_block);
if (block->branch_type == vtn_branch_type_none)
return branch_block;
else
return NULL;
}
case SpvOpReturn:
case SpvOpReturnValue:
block->branch_type = vtn_branch_type_return;
return NULL;
case SpvOpKill:
block->branch_type = vtn_branch_type_discard;
return NULL;
case SpvOpTerminateInvocation:
block->branch_type = vtn_branch_type_terminate_invocation;
return NULL;
case SpvOpIgnoreIntersectionKHR:
block->branch_type = vtn_branch_type_ignore_intersection;
return NULL;
case SpvOpTerminateRayKHR:
block->branch_type = vtn_branch_type_terminate_ray;
return NULL;
case SpvOpBranchConditional: {
struct vtn_value *cond_val = vtn_untyped_value(b, block->branch[1]);
vtn_fail_if(!cond_val->type ||
cond_val->type->base_type != vtn_base_type_scalar ||
cond_val->type->type != glsl_bool_type(),
"Condition must be a Boolean type scalar");
struct vtn_if *if_stmt = rzalloc(b, struct vtn_if);
if_stmt->node.type = vtn_cf_node_type_if;
if_stmt->node.parent = cf_parent;
if_stmt->header_block = block;
list_inithead(&if_stmt->then_body);
list_inithead(&if_stmt->else_body);
list_addtail(&if_stmt->node.link, cf_list);
if (block->merge &&
(*block->merge & SpvOpCodeMask) == SpvOpSelectionMerge) {
/* We may not always have a merge block and that merge doesn't
* technically have to be an OpSelectionMerge. We could have a block
* with an OpLoopMerge which ends in an OpBranchConditional.
*/
if_stmt->merge_block = vtn_block(b, block->merge[1]);
vtn_block_set_merge_cf_node(b, if_stmt->merge_block, &if_stmt->node);
if_stmt->control = block->merge[2];
}
struct vtn_block *then_block = vtn_block(b, block->branch[2]);
if_stmt->then_type = vtn_handle_branch(b, &if_stmt->node, then_block);
if (if_stmt->then_type == vtn_branch_type_none) {
vtn_add_cfg_work_item(b, work_list, &if_stmt->node,
&if_stmt->then_body, then_block);
}
struct vtn_block *else_block = vtn_block(b, block->branch[3]);
if (then_block != else_block) {
if_stmt->else_type = vtn_handle_branch(b, &if_stmt->node, else_block);
if (if_stmt->else_type == vtn_branch_type_none) {
vtn_add_cfg_work_item(b, work_list, &if_stmt->node,
&if_stmt->else_body, else_block);
}
}
return if_stmt->merge_block;
}
case SpvOpSwitch: {
struct vtn_switch *swtch = rzalloc(b, struct vtn_switch);
swtch->node.type = vtn_cf_node_type_switch;
swtch->node.parent = cf_parent;
swtch->selector = block->branch[1];
list_inithead(&swtch->cases);
list_addtail(&swtch->node.link, cf_list);
/* We may not always have a merge block */
if (block->merge) {
vtn_fail_if((*block->merge & SpvOpCodeMask) != SpvOpSelectionMerge,
"An OpLoopMerge instruction must immediately precede "
"either an OpBranch or OpBranchConditional "
"instruction.");
swtch->break_block = vtn_block(b, block->merge[1]);
vtn_block_set_merge_cf_node(b, swtch->break_block, &swtch->node);
}
/* First, we go through and record all of the cases. */
vtn_parse_switch(b, swtch, block->branch, &swtch->cases);
/* Gather the branch types for the switch */
vtn_foreach_cf_node(case_node, &swtch->cases) {
struct vtn_case *cse = vtn_cf_node_as_case(case_node);
cse->type = vtn_handle_branch(b, &swtch->node, cse->block);
switch (cse->type) {
case vtn_branch_type_none:
/* This is a "real" cases which has stuff in it */
vtn_fail_if(cse->block->switch_case != NULL,
"OpSwitch has a case which is also in another "
"OpSwitch construct");
cse->block->switch_case = cse;
vtn_add_cfg_work_item(b, work_list, &cse->node,
&cse->body, cse->block);
break;
case vtn_branch_type_switch_break:
case vtn_branch_type_loop_break:
case vtn_branch_type_loop_continue:
/* Switch breaks as well as loop breaks and continues can be
* used to break out of a switch construct or as direct targets
* of the OpSwitch.
*/
break;
default:
vtn_fail("Target of OpSwitch is not a valid structured exit "
"from the switch construct.");
}
}
return swtch->break_block;
}
case SpvOpUnreachable:
return NULL;
default:
vtn_fail("Block did not end with a valid branch instruction");
}
}
void
vtn_build_cfg(struct vtn_builder *b, const uint32_t *words, const uint32_t *end)
{
vtn_foreach_instruction(b, words, end,
vtn_cfg_handle_prepass_instruction);
if (b->shader->info.stage == MESA_SHADER_KERNEL)
return;
vtn_foreach_cf_node(func_node, &b->functions) {
struct vtn_function *func = vtn_cf_node_as_function(func_node);
/* We build the CFG for each function by doing a breadth-first search on
* the control-flow graph. We keep track of our state using a worklist.
* Doing a BFS ensures that we visit each structured control-flow
* construct and its merge node before we visit the stuff inside the
* construct.
*/
struct list_head work_list;
list_inithead(&work_list);
vtn_add_cfg_work_item(b, &work_list, &func->node, &func->body,
func->start_block);
while (!list_is_empty(&work_list)) {
struct vtn_cfg_work_item *work =
list_first_entry(&work_list, struct vtn_cfg_work_item, link);
list_del(&work->link);
for (struct vtn_block *block = work->start_block; block; ) {
block = vtn_process_block(b, &work_list, work->cf_parent,
work->cf_list, block);
}
}
}
}
static bool
vtn_handle_phis_first_pass(struct vtn_builder *b, SpvOp opcode,
const uint32_t *w, unsigned count)
{
if (opcode == SpvOpLabel)
return true; /* Nothing to do */
/* If this isn't a phi node, stop. */
if (opcode != SpvOpPhi)
return false;
/* For handling phi nodes, we do a poor-man's out-of-ssa on the spot.
* For each phi, we create a variable with the appropreate type and
* do a load from that variable. Then, in a second pass, we add
* stores to that variable to each of the predecessor blocks.
*
* We could do something more intelligent here. However, in order to
* handle loops and things properly, we really need dominance
* information. It would end up basically being the into-SSA
* algorithm all over again. It's easier if we just let
* lower_vars_to_ssa do that for us instead of repeating it here.
*/
struct vtn_type *type = vtn_get_type(b, w[1]);
nir_variable *phi_var =
nir_local_variable_create(b->nb.impl, type->type, "phi");
_mesa_hash_table_insert(b->phi_table, w, phi_var);
vtn_push_ssa_value(b, w[2],
vtn_local_load(b, nir_build_deref_var(&b->nb, phi_var), 0));
return true;
}
static bool
vtn_handle_phi_second_pass(struct vtn_builder *b, SpvOp opcode,
const uint32_t *w, unsigned count)
{
if (opcode != SpvOpPhi)
return true;
struct hash_entry *phi_entry = _mesa_hash_table_search(b->phi_table, w);
/* It's possible that this phi is in an unreachable block in which case it
* may never have been emitted and therefore may not be in the hash table.
* In this case, there's no var for it and it's safe to just bail.
*/
if (phi_entry == NULL)
return true;
nir_variable *phi_var = phi_entry->data;
for (unsigned i = 3; i < count; i += 2) {
struct vtn_block *pred = vtn_block(b, w[i + 1]);
/* If block does not have end_nop, that is because it is an unreacheable
* block, and hence it is not worth to handle it */
if (!pred->end_nop)
continue;
b->nb.cursor = nir_after_instr(&pred->end_nop->instr);
struct vtn_ssa_value *src = vtn_ssa_value(b, w[i]);
vtn_local_store(b, src, nir_build_deref_var(&b->nb, phi_var), 0);
}
return true;
}
static void
vtn_emit_branch(struct vtn_builder *b, enum vtn_branch_type branch_type,
nir_variable *switch_fall_var, bool *has_switch_break)
{
switch (branch_type) {
case vtn_branch_type_if_merge:
break; /* Nothing to do */
case vtn_branch_type_switch_break:
nir_store_var(&b->nb, switch_fall_var, nir_imm_false(&b->nb), 1);
*has_switch_break = true;
break;
case vtn_branch_type_switch_fallthrough:
break; /* Nothing to do */
case vtn_branch_type_loop_break:
nir_jump(&b->nb, nir_jump_break);
break;
case vtn_branch_type_loop_continue:
nir_jump(&b->nb, nir_jump_continue);
break;
case vtn_branch_type_loop_back_edge:
break;
case vtn_branch_type_return:
nir_jump(&b->nb, nir_jump_return);
break;
case vtn_branch_type_discard:
if (b->convert_discard_to_demote)
nir_demote(&b->nb);
else
nir_discard(&b->nb);
break;
case vtn_branch_type_terminate_invocation:
nir_terminate(&b->nb);
break;
case vtn_branch_type_ignore_intersection:
nir_ignore_ray_intersection(&b->nb);
nir_jump(&b->nb, nir_jump_halt);
break;
case vtn_branch_type_terminate_ray:
nir_terminate_ray(&b->nb);
nir_jump(&b->nb, nir_jump_halt);
break;
default:
vtn_fail("Invalid branch type");
}
}
static nir_ssa_def *
vtn_switch_case_condition(struct vtn_builder *b, struct vtn_switch *swtch,
nir_ssa_def *sel, struct vtn_case *cse)
{
if (cse->is_default) {
nir_ssa_def *any = nir_imm_false(&b->nb);
vtn_foreach_cf_node(other_node, &swtch->cases) {
struct vtn_case *other = vtn_cf_node_as_case(other_node);
if (other->is_default)
continue;
any = nir_ior(&b->nb, any,
vtn_switch_case_condition(b, swtch, sel, other));
}
return nir_inot(&b->nb, any);
} else {
nir_ssa_def *cond = nir_imm_false(&b->nb);
util_dynarray_foreach(&cse->values, uint64_t, val)
cond = nir_ior(&b->nb, cond, nir_ieq_imm(&b->nb, sel, *val));
return cond;
}
}
static nir_loop_control
vtn_loop_control(struct vtn_builder *b, struct vtn_loop *vtn_loop)
{
if (vtn_loop->control == SpvLoopControlMaskNone)
return nir_loop_control_none;
else if (vtn_loop->control & SpvLoopControlDontUnrollMask)
return nir_loop_control_dont_unroll;
else if (vtn_loop->control & SpvLoopControlUnrollMask)
return nir_loop_control_unroll;
else if (vtn_loop->control & SpvLoopControlDependencyInfiniteMask ||
vtn_loop->control & SpvLoopControlDependencyLengthMask ||
vtn_loop->control & SpvLoopControlMinIterationsMask ||
vtn_loop->control & SpvLoopControlMaxIterationsMask ||
vtn_loop->control & SpvLoopControlIterationMultipleMask ||
vtn_loop->control & SpvLoopControlPeelCountMask ||
vtn_loop->control & SpvLoopControlPartialCountMask) {
/* We do not do anything special with these yet. */
return nir_loop_control_none;
} else {
vtn_fail("Invalid loop control");
}
}
static nir_selection_control
vtn_selection_control(struct vtn_builder *b, struct vtn_if *vtn_if)
{
if (vtn_if->control == SpvSelectionControlMaskNone)
return nir_selection_control_none;
else if (vtn_if->control & SpvSelectionControlDontFlattenMask)
return nir_selection_control_dont_flatten;
else if (vtn_if->control & SpvSelectionControlFlattenMask)
return nir_selection_control_flatten;
else
vtn_fail("Invalid selection control");
}
static void
vtn_emit_ret_store(struct vtn_builder *b, struct vtn_block *block)
{
if ((*block->branch & SpvOpCodeMask) != SpvOpReturnValue)
return;
vtn_fail_if(b->func->type->return_type->base_type == vtn_base_type_void,
"Return with a value from a function returning void");
struct vtn_ssa_value *src = vtn_ssa_value(b, block->branch[1]);
const struct glsl_type *ret_type =
glsl_get_bare_type(b->func->type->return_type->type);
nir_deref_instr *ret_deref =
nir_build_deref_cast(&b->nb, nir_load_param(&b->nb, 0),
nir_var_function_temp, ret_type, 0);
vtn_local_store(b, src, ret_deref, 0);
}
static void
vtn_emit_cf_list_structured(struct vtn_builder *b, struct list_head *cf_list,
nir_variable *switch_fall_var,
bool *has_switch_break,
vtn_instruction_handler handler)
{
vtn_foreach_cf_node(node, cf_list) {
switch (node->type) {
case vtn_cf_node_type_block: {
struct vtn_block *block = vtn_cf_node_as_block(node);
const uint32_t *block_start = block->label;
const uint32_t *block_end = block->merge ? block->merge :
block->branch;
block_start = vtn_foreach_instruction(b, block_start, block_end,
vtn_handle_phis_first_pass);
vtn_foreach_instruction(b, block_start, block_end, handler);
block->end_nop = nir_nop(&b->nb);
vtn_emit_ret_store(b, block);
if (block->branch_type != vtn_branch_type_none) {
vtn_emit_branch(b, block->branch_type,
switch_fall_var, has_switch_break);
return;
}
break;
}
case vtn_cf_node_type_if: {
struct vtn_if *vtn_if = vtn_cf_node_as_if(node);
const uint32_t *branch = vtn_if->header_block->branch;
vtn_assert((branch[0] & SpvOpCodeMask) == SpvOpBranchConditional);
/* If both branches are the same, just emit the first block, which is
* the only one we filled when building the CFG.
*/
if (branch[2] == branch[3]) {
vtn_emit_cf_list_structured(b, &vtn_if->then_body,
switch_fall_var, has_switch_break, handler);
break;
}
bool sw_break = false;
nir_if *nif =
nir_push_if(&b->nb, vtn_get_nir_ssa(b, branch[1]));
nif->control = vtn_selection_control(b, vtn_if);
if (vtn_if->then_type == vtn_branch_type_none) {
vtn_emit_cf_list_structured(b, &vtn_if->then_body,
switch_fall_var, &sw_break, handler);
} else {
vtn_emit_branch(b, vtn_if->then_type, switch_fall_var, &sw_break);
}
nir_push_else(&b->nb, nif);
if (vtn_if->else_type == vtn_branch_type_none) {
vtn_emit_cf_list_structured(b, &vtn_if->else_body,
switch_fall_var, &sw_break, handler);
} else {
vtn_emit_branch(b, vtn_if->else_type, switch_fall_var, &sw_break);
}
nir_pop_if(&b->nb, nif);
/* If we encountered a switch break somewhere inside of the if,
* then it would have been handled correctly by calling
* emit_cf_list or emit_branch for the interrior. However, we
* need to predicate everything following on wether or not we're
* still going.
*/
if (sw_break) {
*has_switch_break = true;
nir_push_if(&b->nb, nir_load_var(&b->nb, switch_fall_var));
}
break;
}
case vtn_cf_node_type_loop: {
struct vtn_loop *vtn_loop = vtn_cf_node_as_loop(node);
nir_loop *loop = nir_push_loop(&b->nb);
loop->control = vtn_loop_control(b, vtn_loop);
vtn_emit_cf_list_structured(b, &vtn_loop->body, NULL, NULL, handler);
if (!list_is_empty(&vtn_loop->cont_body)) {
/* If we have a non-trivial continue body then we need to put
* it at the beginning of the loop with a flag to ensure that
* it doesn't get executed in the first iteration.
*/
nir_variable *do_cont =
nir_local_variable_create(b->nb.impl, glsl_bool_type(), "cont");
b->nb.cursor = nir_before_cf_node(&loop->cf_node);
nir_store_var(&b->nb, do_cont, nir_imm_false(&b->nb), 1);
b->nb.cursor = nir_before_cf_list(&loop->body);
nir_if *cont_if =
nir_push_if(&b->nb, nir_load_var(&b->nb, do_cont));
vtn_emit_cf_list_structured(b, &vtn_loop->cont_body, NULL, NULL,
handler);
nir_pop_if(&b->nb, cont_if);
nir_store_var(&b->nb, do_cont, nir_imm_true(&b->nb), 1);
}
nir_pop_loop(&b->nb, loop);
break;
}
case vtn_cf_node_type_switch: {
struct vtn_switch *vtn_switch = vtn_cf_node_as_switch(node);
/* Before we can emit anything, we need to sort the list of cases in
* fall-through order.
*/
vtn_switch_order_cases(vtn_switch);
/* First, we create a variable to keep track of whether or not the
* switch is still going at any given point. Any switch breaks
* will set this variable to false.
*/
nir_variable *fall_var =
nir_local_variable_create(b->nb.impl, glsl_bool_type(), "fall");
nir_store_var(&b->nb, fall_var, nir_imm_false(&b->nb), 1);
nir_ssa_def *sel = vtn_get_nir_ssa(b, vtn_switch->selector);
/* Now we can walk the list of cases and actually emit code */
vtn_foreach_cf_node(case_node, &vtn_switch->cases) {
struct vtn_case *cse = vtn_cf_node_as_case(case_node);
/* If this case jumps directly to the break block, we don't have
* to handle the case as the body is empty and doesn't fall
* through.
*/
if (cse->block == vtn_switch->break_block)
continue;
/* Figure out the condition */
nir_ssa_def *cond =
vtn_switch_case_condition(b, vtn_switch, sel, cse);
/* Take fallthrough into account */
cond = nir_ior(&b->nb, cond, nir_load_var(&b->nb, fall_var));
nir_if *case_if = nir_push_if(&b->nb, cond);
bool has_break = false;
nir_store_var(&b->nb, fall_var, nir_imm_true(&b->nb), 1);
vtn_emit_cf_list_structured(b, &cse->body, fall_var, &has_break,
handler);
(void)has_break; /* We don't care */
nir_pop_if(&b->nb, case_if);
}
break;
}
default:
vtn_fail("Invalid CF node type");
}
}
}
static struct nir_block *
vtn_new_unstructured_block(struct vtn_builder *b, struct vtn_function *func)
{
struct nir_block *n = nir_block_create(b->shader);
exec_list_push_tail(&func->nir_func->impl->body, &n->cf_node.node);
n->cf_node.parent = &func->nir_func->impl->cf_node;
return n;
}
static void
vtn_add_unstructured_block(struct vtn_builder *b,
struct vtn_function *func,
struct list_head *work_list,
struct vtn_block *block)
{
if (!block->block) {
block->block = vtn_new_unstructured_block(b, func);
list_addtail(&block->node.link, work_list);
}
}
static void
vtn_emit_cf_func_unstructured(struct vtn_builder *b, struct vtn_function *func,
vtn_instruction_handler handler)
{
struct list_head work_list;
list_inithead(&work_list);
func->start_block->block = nir_start_block(func->nir_func->impl);
list_addtail(&func->start_block->node.link, &work_list);
while (!list_is_empty(&work_list)) {
struct vtn_block *block =
list_first_entry(&work_list, struct vtn_block, node.link);
list_del(&block->node.link);
vtn_assert(block->block);
const uint32_t *block_start = block->label;
const uint32_t *block_end = block->branch;
b->nb.cursor = nir_after_block(block->block);
block_start = vtn_foreach_instruction(b, block_start, block_end,
vtn_handle_phis_first_pass);
vtn_foreach_instruction(b, block_start, block_end, handler);
block->end_nop = nir_nop(&b->nb);
SpvOp op = *block_end & SpvOpCodeMask;
switch (op) {
case SpvOpBranch: {
struct vtn_block *branch_block = vtn_block(b, block->branch[1]);
vtn_add_unstructured_block(b, func, &work_list, branch_block);
nir_goto(&b->nb, branch_block->block);
break;
}
case SpvOpBranchConditional: {
nir_ssa_def *cond = vtn_ssa_value(b, block->branch[1])->def;
struct vtn_block *then_block = vtn_block(b, block->branch[2]);
struct vtn_block *else_block = vtn_block(b, block->branch[3]);
vtn_add_unstructured_block(b, func, &work_list, then_block);
if (then_block == else_block) {
nir_goto(&b->nb, then_block->block);
} else {
vtn_add_unstructured_block(b, func, &work_list, else_block);
nir_goto_if(&b->nb, then_block->block, nir_src_for_ssa(cond),
else_block->block);
}
break;
}
case SpvOpSwitch: {
struct list_head cases;
list_inithead(&cases);
vtn_parse_switch(b, NULL, block->branch, &cases);
nir_ssa_def *sel = vtn_get_nir_ssa(b, block->branch[1]);
struct vtn_case *def = NULL;
vtn_foreach_cf_node(case_node, &cases) {
struct vtn_case *cse = vtn_cf_node_as_case(case_node);
if (cse->is_default) {
assert(def == NULL);
def = cse;
continue;
}
nir_ssa_def *cond = nir_imm_false(&b->nb);
util_dynarray_foreach(&cse->values, uint64_t, val)
cond = nir_ior(&b->nb, cond, nir_ieq_imm(&b->nb, sel, *val));
/* block for the next check */
nir_block *e = vtn_new_unstructured_block(b, func);
vtn_add_unstructured_block(b, func, &work_list, cse->block);
/* add branching */
nir_goto_if(&b->nb, cse->block->block, nir_src_for_ssa(cond), e);
b->nb.cursor = nir_after_block(e);
}
vtn_assert(def != NULL);
vtn_add_unstructured_block(b, func, &work_list, def->block);
/* now that all cases are handled, branch into the default block */
nir_goto(&b->nb, def->block->block);
break;
}
case SpvOpKill: {
nir_discard(&b->nb);
nir_goto(&b->nb, b->func->nir_func->impl->end_block);
break;
}
case SpvOpUnreachable:
case SpvOpReturn:
case SpvOpReturnValue: {
vtn_emit_ret_store(b, block);
nir_goto(&b->nb, b->func->nir_func->impl->end_block);
break;
}
default:
vtn_fail("Unhandled opcode %s", spirv_op_to_string(op));
}
}
}
void
vtn_function_emit(struct vtn_builder *b, struct vtn_function *func,
vtn_instruction_handler instruction_handler)
{
static int force_unstructured = -1;
if (force_unstructured < 0) {
force_unstructured =
env_var_as_boolean("MESA_SPIRV_FORCE_UNSTRUCTURED", false);
}
nir_function_impl *impl = func->nir_func->impl;
nir_builder_init(&b->nb, impl);
b->func = func;
b->nb.cursor = nir_after_cf_list(&impl->body);
b->nb.exact = b->exact;
b->phi_table = _mesa_pointer_hash_table_create(b);
if (b->shader->info.stage == MESA_SHADER_KERNEL || force_unstructured) {
impl->structured = false;
vtn_emit_cf_func_unstructured(b, func, instruction_handler);
} else {
vtn_emit_cf_list_structured(b, &func->body, NULL, NULL,
instruction_handler);
}
vtn_foreach_instruction(b, func->start_block->label, func->end,
vtn_handle_phi_second_pass);
if (func->nir_func->impl->structured)
nir_copy_prop_impl(impl);
nir_rematerialize_derefs_in_use_blocks_impl(impl);
/*
* There are some cases where we need to repair SSA to insert
* the needed phi nodes:
*
* - Continue blocks for loops get inserted before the body of the loop
* but instructions in the continue may use SSA defs in the loop body.
*
* - Early termination instructions `OpKill` and `OpTerminateInvocation`,
* in NIR. They're represented by regular intrinsics with no control-flow
* semantics. This means that the SSA form from the SPIR-V may not
* 100% match NIR.
*
* - Switches with only default case may also define SSA which may
* subsequently be used out of the switch.
*/
if (func->nir_func->impl->structured)
nir_repair_ssa_impl(impl);
func->emitted = true;
}