[spirv-reader] Improve placement of hoisted vars
When we hoist a variable out of a continue construct, put it in associated loop construct, if it exists. This reduces its lifetime in WGSL, and easier to understand as a code reader. Change-Id: I8f0cc37640bfe67874cbc27b55029e79e9a8992c Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/24321 Reviewed-by: dan sinclair <dsinclair@google.com>
This commit is contained in:
David Neto
dan sinclair
parent
4c48622aa1
commit
91cb60f2ec
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@ -218,6 +218,13 @@ inline std::string ToString(const Construct& c) {
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return ss.str();
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}
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/// Converts a construct to a string.
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/// @param c the construct
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/// @returns the string representation
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inline std::string ToString(const Construct* c) {
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return c ? ToString(*c) : ToStringBrief(c);
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}
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/// Converts a unique pointer to a construct to a string.
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/// @param c the construct
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/// @returns the string representation
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@ -1145,6 +1145,30 @@ BlockInfo* FunctionEmitter::HeaderIfBreakable(const Construct* c) {
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return nullptr;
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}
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const Construct* FunctionEmitter::SiblingLoopConstruct(
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const Construct* c) const {
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if (c == nullptr || c->kind != Construct::kContinue) {
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return nullptr;
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}
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const uint32_t continue_target_id = c->begin_id;
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const auto* continue_target = GetBlockInfo(continue_target_id);
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const uint32_t header_id = continue_target->header_for_continue;
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if (continue_target_id == header_id) {
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// The continue target is the whole loop.
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return nullptr;
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}
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const auto* candidate = GetBlockInfo(header_id)->construct;
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// Walk up the construct tree until we hit the loop. In future
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// we might handle the corner case where the same block is both a
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// loop header and a selection header. For example, where the
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// loop header block has a conditional branch going to distinct
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// targets inside the loop body.
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while (candidate && candidate->kind != Construct::kLoop) {
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candidate = candidate->parent;
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}
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return candidate;
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}
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bool FunctionEmitter::ClassifyCFGEdges() {
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if (failed()) {
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return false;
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@ -3013,13 +3037,17 @@ void FunctionEmitter::RegisterValuesNeedingNamedOrHoistedDefinition() {
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const auto block_pos = block_info->pos;
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for (const auto& inst : *(block_info->basic_block)) {
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// Update the usage span for IDs used by this instruction.
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inst.ForEachInId([this, block_pos](const uint32_t* id_ptr) {
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auto* def_info = GetDefInfo(*id_ptr);
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if (def_info) {
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def_info->num_uses++;
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def_info->last_use_pos = std::max(def_info->last_use_pos, block_pos);
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}
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});
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// But skip uses in OpPhi because they are handled differently.
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if (inst.opcode() != SpvOpPhi) {
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inst.ForEachInId([this, block_pos](const uint32_t* id_ptr) {
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auto* def_info = GetDefInfo(*id_ptr);
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if (def_info) {
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def_info->num_uses++;
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def_info->last_use_pos =
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std::max(def_info->last_use_pos, block_pos);
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}
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});
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}
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if (inst.opcode() == SpvOpPhi) {
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// Declare a name for the variable used to carry values to a phi.
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@ -3051,7 +3079,7 @@ void FunctionEmitter::RegisterValuesNeedingNamedOrHoistedDefinition() {
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// Schedule the declaration of the state variable.
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const auto* enclosing_construct =
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GetSmallestEnclosingConstruct(first_pos, last_pos);
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GetEnclosingScope(first_pos, last_pos);
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GetBlockInfo(enclosing_construct->begin_id)
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->phis_needing_state_vars.push_back(phi_id);
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}
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@ -3088,7 +3116,7 @@ void FunctionEmitter::RegisterValuesNeedingNamedOrHoistedDefinition() {
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if (def_in_construct != construct_with_last_use) {
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const auto* enclosing_construct =
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GetSmallestEnclosingConstruct(first_pos, last_use_pos);
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GetEnclosingScope(first_pos, last_use_pos);
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if (enclosing_construct == def_in_construct) {
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// We can use a plain 'const' definition.
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def_info->requires_named_const_def = true;
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@ -3103,15 +3131,19 @@ void FunctionEmitter::RegisterValuesNeedingNamedOrHoistedDefinition() {
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}
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}
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const Construct* FunctionEmitter::GetSmallestEnclosingConstruct(
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uint32_t first_pos,
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uint32_t last_pos) const {
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const Construct* FunctionEmitter::GetEnclosingScope(uint32_t first_pos,
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uint32_t last_pos) const {
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const auto* enclosing_construct =
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GetBlockInfo(block_order_[first_pos])->construct;
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assert(enclosing_construct != nullptr);
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// Constructs are strictly nesting, so follow parent pointers
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while (enclosing_construct && !enclosing_construct->ContainsPos(last_pos)) {
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enclosing_construct = enclosing_construct->parent;
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// The scope of a continue construct is enclosed in its associated loop
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// construct, but they are siblings in our construct tree.
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const auto* sibling_loop = SiblingLoopConstruct(enclosing_construct);
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// Go to the sibling loop if it exists, otherwise walk up to the parent.
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enclosing_construct =
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sibling_loop ? sibling_loop : enclosing_construct->parent;
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}
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// At worst, we go all the way out to the function construct.
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assert(enclosing_construct != nullptr);
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@ -601,14 +601,23 @@ class FunctionEmitter {
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return where->second.get();
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}
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/// Returns the most deeply nested structured construct which encloses
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/// both block positions. Each position must be a valid index into the
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/// function block order array.
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/// Returns the most deeply nested structured construct which encloses the
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/// WGSL scopes of names declared in both block positions. Each position must
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/// be a valid index into the function block order array.
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/// @param first_pos the first block position
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/// @param last_pos the last block position
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/// @returns the smallest construct containing both positions
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const Construct* GetSmallestEnclosingConstruct(uint32_t first_pos,
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uint32_t last_pos) const;
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const Construct* GetEnclosingScope(uint32_t first_pos,
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uint32_t last_pos) const;
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/// Finds loop construct associated with a continue construct, if it exists.
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/// Returns nullptr if:
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/// - the given construct is not a continue construct
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/// - the continue construct does not have an associated loop construct
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/// (the continue target is also the loop header block)
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/// @param c the continue construct
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/// @returns the associated loop construct, or nullptr
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const Construct* SiblingLoopConstruct(const Construct* c) const;
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private:
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/// @returns the store type for the OpVariable instruction, or
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@ -17,6 +17,7 @@
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#include <vector>
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#include "gmock/gmock.h"
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#include "src/reader/spirv/construct.h"
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#include "src/reader/spirv/function.h"
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#include "src/reader/spirv/parser_impl.h"
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#include "src/reader/spirv/parser_impl_test_helper.h"
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@ -87,15 +88,22 @@ std::string CommonTypes() {
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)";
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}
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/// Runs the necessary flow until and including finding switch case
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/// headers.
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/// @returns the result of finding switch case headers.
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bool FlowFindSwitchCaseHeaders(FunctionEmitter* fe) {
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/// Runs the necessary flow until and including labeling control
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/// flow constructs.
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/// @returns the result of labeling control flow constructs.
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bool FlowLabelControlFlowConstructs(FunctionEmitter* fe) {
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fe->RegisterBasicBlocks();
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EXPECT_TRUE(fe->RegisterMerges()) << fe->parser()->error();
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fe->ComputeBlockOrderAndPositions();
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EXPECT_TRUE(fe->VerifyHeaderContinueMergeOrder()) << fe->parser()->error();
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EXPECT_TRUE(fe->LabelControlFlowConstructs()) << fe->parser()->error();
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return fe->LabelControlFlowConstructs();
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}
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/// Runs the necessary flow until and including finding switch case
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/// headers.
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/// @returns the result of finding switch case headers.
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bool FlowFindSwitchCaseHeaders(FunctionEmitter* fe) {
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EXPECT_TRUE(FlowLabelControlFlowConstructs(fe)) << fe->parser()->error();
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return fe->FindSwitchCaseHeaders();
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}
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@ -13418,6 +13426,121 @@ TEST_F(SpvParserTest,
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<< ToString(fe.ast_body());
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}
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TEST_F(SpvParserTest, SiblingLoopConstruct_Null) {
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auto assembly = CommonTypes() + R"(
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%100 = OpFunction %void None %voidfn
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%10 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
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FunctionEmitter fe(p, *spirv_function(100));
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EXPECT_EQ(fe.SiblingLoopConstruct(nullptr), nullptr);
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}
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TEST_F(SpvParserTest, SiblingLoopConstruct_NotAContinue) {
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auto assembly = CommonTypes() + R"(
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%100 = OpFunction %void None %voidfn
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%10 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
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FunctionEmitter fe(p, *spirv_function(100));
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ASSERT_TRUE(FlowLabelControlFlowConstructs(&fe)) << p->error();
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const Construct* c = fe.GetBlockInfo(10)->construct;
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EXPECT_NE(c, nullptr);
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EXPECT_EQ(fe.SiblingLoopConstruct(c), nullptr);
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}
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TEST_F(SpvParserTest, SiblingLoopConstruct_SingleBlockLoop) {
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auto assembly = CommonTypes() + R"(
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%100 = OpFunction %void None %voidfn
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%10 = OpLabel
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OpBranch %20
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%20 = OpLabel
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OpLoopMerge %99 %20 None
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OpBranchConditional %cond %20 %99
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%99 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
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FunctionEmitter fe(p, *spirv_function(100));
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ASSERT_TRUE(FlowLabelControlFlowConstructs(&fe)) << p->error();
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const Construct* c = fe.GetBlockInfo(20)->construct;
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EXPECT_EQ(c->kind, Construct::kContinue);
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EXPECT_EQ(fe.SiblingLoopConstruct(c), nullptr);
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}
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TEST_F(SpvParserTest, SiblingLoopConstruct_ContinueIsWholeMultiBlockLoop) {
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auto assembly = CommonTypes() + R"(
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%100 = OpFunction %void None %voidfn
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%10 = OpLabel
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OpBranch %20
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%20 = OpLabel
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OpLoopMerge %99 %20 None ; continue target is also loop header
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OpBranchConditional %cond %30 %99
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%30 = OpLabel
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OpBranch %20
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%99 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions())
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<< p->error() << assembly;
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FunctionEmitter fe(p, *spirv_function(100));
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ASSERT_TRUE(FlowLabelControlFlowConstructs(&fe)) << p->error();
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const Construct* c = fe.GetBlockInfo(20)->construct;
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EXPECT_EQ(c->kind, Construct::kContinue);
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EXPECT_EQ(fe.SiblingLoopConstruct(c), nullptr);
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}
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TEST_F(SpvParserTest, SiblingLoopConstruct_HasSiblingLoop) {
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auto assembly = CommonTypes() + R"(
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%100 = OpFunction %void None %voidfn
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%10 = OpLabel
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OpBranch %20
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%20 = OpLabel
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OpLoopMerge %99 %30 None
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OpBranchConditional %cond %30 %99
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%30 = OpLabel ; continue target
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OpBranch %20
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%99 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions()) << p->error();
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FunctionEmitter fe(p, *spirv_function(100));
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ASSERT_TRUE(FlowLabelControlFlowConstructs(&fe)) << p->error();
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const Construct* c = fe.GetBlockInfo(30)->construct;
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EXPECT_EQ(c->kind, Construct::kContinue);
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EXPECT_THAT(ToString(fe.SiblingLoopConstruct(c)),
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Eq("Construct{ Loop [1,2) begin_id:20 end_id:30 depth:1 "
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"parent:Function@10 in-l:Loop@20 }"));
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}
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} // namespace
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} // namespace spirv
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} // namespace reader
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@ -1042,13 +1042,23 @@ TEST_F(SpvParserTest, EmitStatement_Phi_SingleBlockLoopIndex) {
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}
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}
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}
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VariableDeclStatement{
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Variable{
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x_4
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none
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__u32
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{
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Binary{
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Identifier{x_2}
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add
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ScalarConstructor{1}
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}
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}
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}
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}
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Assignment{
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Identifier{x_2_phi}
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Binary{
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Identifier{x_2}
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add
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ScalarConstructor{1}
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}
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Identifier{x_4}
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}
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Assignment{
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Identifier{x_3_phi}
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@ -1120,13 +1130,6 @@ TEST_F(SpvParserTest, EmitStatement_Phi_MultiBlockLoopIndex) {
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__u32
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}
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}
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VariableDeclStatement{
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Variable{
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x_4
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function
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__u32
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}
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}
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VariableDeclStatement{
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Variable{
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x_2_phi
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@ -1201,12 +1204,18 @@ TEST_F(SpvParserTest, EmitStatement_Phi_MultiBlockLoopIndex) {
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}
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}
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continuing {
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Assignment{
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Identifier{x_4}
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Binary{
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Identifier{x_2}
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add
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ScalarConstructor{1}
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VariableDeclStatement{
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Variable{
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x_4
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none
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__u32
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{
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Binary{
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Identifier{x_2}
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add
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ScalarConstructor{1}
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}
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}
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}
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}
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Assignment{
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@ -1224,6 +1233,174 @@ Return{}
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)")) << ToString(fe.ast_body());
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}
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TEST_F(SpvParserTest, EmitStatement_Phi_ValueFromLoopBodyAndContinuing) {
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auto assembly = Preamble() + R"(
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%pty = OpTypePointer Private %uint
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%1 = OpVariable %pty Private
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%boolpty = OpTypePointer Private %bool
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%17 = OpVariable %boolpty Private
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%100 = OpFunction %void None %voidfn
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%9 = OpLabel
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%101 = OpLoad %bool %17
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OpBranch %10
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; Use an outer loop to show we put the new variable in the
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; smallest enclosing scope.
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%10 = OpLabel
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OpLoopMerge %99 %89 None
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OpBranch %20
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%20 = OpLabel
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%2 = OpPhi %uint %uint_0 %10 %4 %30 ; gets computed value
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%5 = OpPhi %uint %uint_1 %10 %7 %30
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%4 = OpIAdd %uint %2 %uint_1 ; define %4
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%6 = OpIAdd %uint %4 %uint_1 ; use %4
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OpLoopMerge %89 %30 None
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OpBranchConditional %101 %89 %30
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%30 = OpLabel
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%7 = OpIAdd %uint %4 %6 ; use %4 again
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OpBranch %20
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%89 = OpLabel
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OpBranch %10
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%99 = OpLabel
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OpReturn
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OpFunctionEnd
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)";
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auto* p = parser(test::Assemble(assembly));
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ASSERT_TRUE(p->BuildAndParseInternalModuleExceptFunctions())
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<< assembly << p->error();
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FunctionEmitter fe(p, *spirv_function(100));
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EXPECT_TRUE(fe.EmitBody()) << p->error();
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EXPECT_THAT(ToString(fe.ast_body()), Eq(R"(VariableDeclStatement{
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Variable{
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x_101
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none
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__bool
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{
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Identifier{x_17}
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}
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}
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}
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Loop{
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VariableDeclStatement{
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Variable{
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x_4
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function
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__u32
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}
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}
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VariableDeclStatement{
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Variable{
|
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x_6
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function
|
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__u32
|
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}
|
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}
|
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VariableDeclStatement{
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Variable{
|
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x_2_phi
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function
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__u32
|
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}
|
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}
|
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VariableDeclStatement{
|
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Variable{
|
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x_5_phi
|
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function
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__u32
|
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}
|
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}
|
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Assignment{
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Identifier{x_2_phi}
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ScalarConstructor{0}
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}
|
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Assignment{
|
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Identifier{x_5_phi}
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ScalarConstructor{1}
|
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}
|
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Loop{
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VariableDeclStatement{
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Variable{
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x_2
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none
|
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__u32
|
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{
|
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Identifier{x_2_phi}
|
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}
|
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}
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}
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VariableDeclStatement{
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Variable{
|
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x_5
|
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none
|
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__u32
|
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{
|
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Identifier{x_5_phi}
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}
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||||
}
|
||||
}
|
||||
Assignment{
|
||||
Identifier{x_4}
|
||||
Binary{
|
||||
Identifier{x_2}
|
||||
add
|
||||
ScalarConstructor{1}
|
||||
}
|
||||
}
|
||||
Assignment{
|
||||
Identifier{x_6}
|
||||
Binary{
|
||||
Identifier{x_4}
|
||||
add
|
||||
ScalarConstructor{1}
|
||||
}
|
||||
}
|
||||
If{
|
||||
(
|
||||
Identifier{x_101}
|
||||
)
|
||||
{
|
||||
Break{}
|
||||
}
|
||||
}
|
||||
continuing {
|
||||
VariableDeclStatement{
|
||||
Variable{
|
||||
x_7
|
||||
none
|
||||
__u32
|
||||
{
|
||||
Binary{
|
||||
Identifier{x_4}
|
||||
add
|
||||
Identifier{x_6}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
Assignment{
|
||||
Identifier{x_2_phi}
|
||||
Identifier{x_4}
|
||||
}
|
||||
Assignment{
|
||||
Identifier{x_5_phi}
|
||||
Identifier{x_7}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
Return{}
|
||||
)")) << ToString(fe.ast_body())
|
||||
<< assembly;
|
||||
}
|
||||
|
||||
TEST_F(SpvParserTest, EmitStatement_Phi_FromElseAndThen) {
|
||||
auto assembly = Preamble() + R"(
|
||||
%pty = OpTypePointer Private %uint
|
||||
|
|
|
|||
Loading…
Reference in New Issue