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[IR] Add switch control flow node. 

This CL updates the IR builder to create control flow nodes for
a switch statement and the contained case statements.

Bug: tint:1718
Change-Id: I05b73db11ab14676cc123f436ae5912b1dbee0d5
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/107801
Reviewed-by: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Commit-Queue: Dan Sinclair <dsinclair@chromium.org>
This commit is contained in:
dan sinclair 2022-11-01 14:34:08 +00:00 committed by Dawn LUCI CQ
parent b9ed75cf2f
commit d336733c83
7 changed files with 317 additions and 12 deletions
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15
src/tint/ir/builder.cc
View File

@ -71,6 +71,21 @@ Loop* Builder::CreateLoop(const ast::LoopStatement* stmt) {
return ir_loop;
}
Switch* Builder::CreateSwitch(const ast::SwitchStatement* stmt) {
auto* ir_switch = ir.flow_nodes.Create<Switch>(stmt);
ir_switch->merge_target = CreateBlock();
return ir_switch;
}
Block* Builder::CreateCase(Switch* s, const utils::VectorRef<const ast::CaseSelector*> selectors) {
s->cases.Push(Switch::Case{selectors, CreateBlock()});
Block* b = s->cases.Back().start_target;
// Switch branches into the case block
b->inbound_branches.Push(s);
return b;
}
void Builder::Branch(Block* from, FlowNode* to) {
TINT_ASSERT(IR, from);
TINT_ASSERT(IR, to);

14
src/tint/ir/builder.h
View File

@ -26,6 +26,9 @@
namespace tint {
class Program;
} // namespace tint
namespace tint::ast {
class CaseSelector;
} // namespace tint::ast
namespace tint::ir {
@ -62,6 +65,17 @@ class Builder {
/// @returns the flow node
Loop* CreateLoop(const ast::LoopStatement* stmt);
/// Creates a switch flow node for the given ast::SwitchStatement
/// @param stmt the ast::SwitchStatment
/// @returns the flow node
Switch* CreateSwitch(const ast::SwitchStatement* stmt);
/// Creates a case flow node for the given case branch.
/// @param s the switch to create the case into
/// @param selectors the case selectors for the case statement
/// @returns the start block for the case flow node
Block* CreateCase(Switch* s, const utils::VectorRef<const ast::CaseSelector*> selectors);
/// Branches the given block to the given flow node.
/// @param from the block to branch from
/// @param to the node to branch too

48
src/tint/ir/builder_impl.cc
View File

@ -24,6 +24,7 @@
#include "src/tint/ast/return_statement.h"
#include "src/tint/ast/statement.h"
#include "src/tint/ast/static_assert.h"
#include "src/tint/ast/switch_statement.h"
#include "src/tint/ir/function.h"
#include "src/tint/ir/if.h"
#include "src/tint/ir/loop.h"
@ -209,7 +210,7 @@ bool BuilderImpl::EmitStatement(const ast::Statement* stmt) {
// [&](const ast::ForLoopStatement* l) { },
// [&](const ast::WhileStatement* l) { },
[&](const ast::ReturnStatement* r) { return EmitReturn(r); },
// [&](const ast::SwitchStatement* s) { },
[&](const ast::SwitchStatement* s) { return EmitSwitch(s); },
// [&](const ast::VariableDeclStatement* v) { },
[&](const ast::StaticAssert*) {
return true; // Not emitted
@ -254,15 +255,6 @@ bool BuilderImpl::EmitIf(const ast::IfStatement* stmt) {
}
current_flow_block_ = nullptr;
// If both branches went somewhere, then they both returned, continued or broke. So,
// there is no need for the if merge-block and there is nothing to branch to the merge
// block anyway.
if (IsBranched(if_node->true_target) && IsBranched(if_node->false_target)) {
return true;
}
current_flow_block_ = if_node->merge_target;
// If the true branch did not execute control flow, then go to the merge target
if (!IsBranched(if_node->true_target)) {
builder_.Branch(if_node->true_target, if_node->merge_target);
@ -272,6 +264,13 @@ bool BuilderImpl::EmitIf(const ast::IfStatement* stmt) {
builder_.Branch(if_node->false_target, if_node->merge_target);
}
// If both branches went somewhere, then they both returned, continued or broke. So,
// there is no need for the if merge-block and there is nothing to branch to the merge
// block anyway.
if (IsConnected(if_node->merge_target)) {
current_flow_block_ = if_node->merge_target;
}
return true;
}
@ -313,6 +312,35 @@ bool BuilderImpl::EmitLoop(const ast::LoopStatement* stmt) {
return true;
}
bool BuilderImpl::EmitSwitch(const ast::SwitchStatement* stmt) {
auto* switch_node = builder_.CreateSwitch(stmt);
// TODO(dsinclair): Emit the condition expression into the current block
BranchTo(switch_node);
ast_to_flow_[stmt] = switch_node;
{
FlowStackScope scope(this, switch_node);
for (const auto* c : stmt->body) {
current_flow_block_ = builder_.CreateCase(switch_node, c->selectors);
if (!EmitStatement(c->body)) {
return false;
}
BranchToIfNeeded(switch_node->merge_target);
}
}
current_flow_block_ = nullptr;
if (IsConnected(switch_node->merge_target)) {
current_flow_block_ = switch_node->merge_target;
}
return true;
}
bool BuilderImpl::EmitReturn(const ast::ReturnStatement*) {
// TODO(dsinclair): Emit the return value ....

5
src/tint/ir/builder_impl.h
View File

@ -102,6 +102,11 @@ class BuilderImpl {
/// @returns true if successful, false otherwise.
bool EmitLoop(const ast::LoopStatement* stmt);
/// Emits a switch statement
/// @param stmt the switch statement
/// @returns true if successfull, false otherwise.
bool EmitSwitch(const ast::SwitchStatement* stmt);
/// Emits a break statement
/// @param stmt the break statement
/// @returns true if successfull, false otherwise.

222
src/tint/ir/builder_impl_test.cc
View File

@ -14,9 +14,14 @@
#include "src/tint/ir/test_helper.h"
#include "src/tint/ast/case_selector.h"
#include "src/tint/ast/int_literal_expression.h"
namespace tint::ir {
namespace {
using namespace tint::number_suffixes; // NOLINT
using IRBuilderImplTest = TestHelper;
TEST_F(IRBuilderImplTest, Func) {
@ -817,5 +822,222 @@ TEST_F(IRBuilderImplTest, Loop_Nested) {
EXPECT_EQ(loop_flow_a->merge_target->branch_target, func->end_target);
}
TEST_F(IRBuilderImplTest, Switch) {
// func -> switch -> case 1
// -> case 2
// -> default
//
// [case 1] -> switch merge
// [case 2] -> switch merge
// [default] -> switch merge
// [switch merge] -> func end
//
auto* ast_switch = Switch(
1_i, utils::Vector{Case(utils::Vector{CaseSelector(0_i)}, Block()),
Case(utils::Vector{CaseSelector(1_i)}, Block()), DefaultCase(Block())});
WrapInFunction(ast_switch);
auto& b = Build();
auto r = b.Build();
ASSERT_TRUE(r) << b.error();
auto m = r.Move();
auto* ir_switch = b.FlowNodeForAstNode(ast_switch);
ASSERT_NE(ir_switch, nullptr);
ASSERT_TRUE(ir_switch->Is<ir::Switch>());
auto* flow = ir_switch->As<ir::Switch>();
ASSERT_NE(flow->merge_target, nullptr);
ASSERT_EQ(3u, flow->cases.Length());
ASSERT_EQ(1u, m.functions.Length());
auto* func = m.functions[0];
ASSERT_EQ(1u, flow->cases[0].selectors.Length());
ASSERT_TRUE(flow->cases[0].selectors[0]->expr->Is<ast::IntLiteralExpression>());
EXPECT_EQ(0_i, flow->cases[0].selectors[0]->expr->As<ast::IntLiteralExpression>()->value);
ASSERT_EQ(1u, flow->cases[1].selectors.Length());
ASSERT_TRUE(flow->cases[1].selectors[0]->expr->Is<ast::IntLiteralExpression>());
EXPECT_EQ(1_i, flow->cases[1].selectors[0]->expr->As<ast::IntLiteralExpression>()->value);
ASSERT_EQ(1u, flow->cases[2].selectors.Length());
EXPECT_TRUE(flow->cases[2].selectors[0]->IsDefault());
EXPECT_EQ(1u, flow->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[0].start_target->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[1].start_target->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[2].start_target->inbound_branches.Length());
EXPECT_EQ(3u, flow->merge_target->inbound_branches.Length());
EXPECT_EQ(1u, func->end_target->inbound_branches.Length());
EXPECT_EQ(func->start_target->branch_target, ir_switch);
EXPECT_EQ(flow->cases[0].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->cases[1].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->cases[2].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->merge_target->branch_target, func->end_target);
}
TEST_F(IRBuilderImplTest, Switch_OnlyDefault) {
// func -> switch -> default -> switch merge -> func end
//
auto* ast_switch = Switch(1_i, utils::Vector{DefaultCase(Block())});
WrapInFunction(ast_switch);
auto& b = Build();
auto r = b.Build();
ASSERT_TRUE(r) << b.error();
auto m = r.Move();
auto* ir_switch = b.FlowNodeForAstNode(ast_switch);
ASSERT_NE(ir_switch, nullptr);
ASSERT_TRUE(ir_switch->Is<ir::Switch>());
auto* flow = ir_switch->As<ir::Switch>();
ASSERT_NE(flow->merge_target, nullptr);
ASSERT_EQ(1u, flow->cases.Length());
ASSERT_EQ(1u, m.functions.Length());
auto* func = m.functions[0];
ASSERT_EQ(1u, flow->cases[0].selectors.Length());
EXPECT_TRUE(flow->cases[0].selectors[0]->IsDefault());
EXPECT_EQ(1u, flow->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[0].start_target->inbound_branches.Length());
EXPECT_EQ(1u, flow->merge_target->inbound_branches.Length());
EXPECT_EQ(1u, func->end_target->inbound_branches.Length());
EXPECT_EQ(func->start_target->branch_target, ir_switch);
EXPECT_EQ(flow->cases[0].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->merge_target->branch_target, func->end_target);
}
TEST_F(IRBuilderImplTest, Switch_WithBreak) {
// {
// switch(1) {
// case 0: {
// break;
// if true { return;} // Dead code
// }
// default: {}
// }
// }
//
// func -> switch -> case 1
// -> default
//
// [case 1] -> switch merge
// [default] -> switch merge
// [switch merge] -> func end
auto* ast_switch = Switch(1_i, utils::Vector{Case(utils::Vector{CaseSelector(0_i)},
Block(Break(), If(true, Block(Return())))),
DefaultCase(Block())});
WrapInFunction(ast_switch);
auto& b = Build();
auto r = b.Build();
ASSERT_TRUE(r) << b.error();
auto m = r.Move();
auto* ir_switch = b.FlowNodeForAstNode(ast_switch);
ASSERT_NE(ir_switch, nullptr);
ASSERT_TRUE(ir_switch->Is<ir::Switch>());
auto* flow = ir_switch->As<ir::Switch>();
ASSERT_NE(flow->merge_target, nullptr);
ASSERT_EQ(2u, flow->cases.Length());
ASSERT_EQ(1u, m.functions.Length());
auto* func = m.functions[0];
ASSERT_EQ(1u, flow->cases[0].selectors.Length());
ASSERT_TRUE(flow->cases[0].selectors[0]->expr->Is<ast::IntLiteralExpression>());
EXPECT_EQ(0_i, flow->cases[0].selectors[0]->expr->As<ast::IntLiteralExpression>()->value);
ASSERT_EQ(1u, flow->cases[1].selectors.Length());
EXPECT_TRUE(flow->cases[1].selectors[0]->IsDefault());
EXPECT_EQ(1u, flow->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[0].start_target->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[1].start_target->inbound_branches.Length());
EXPECT_EQ(2u, flow->merge_target->inbound_branches.Length());
// This is 1 because the if is dead-code eliminated and the return doesn't happen.
EXPECT_EQ(1u, func->end_target->inbound_branches.Length());
EXPECT_EQ(func->start_target->branch_target, ir_switch);
EXPECT_EQ(flow->cases[0].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->cases[1].start_target->branch_target, flow->merge_target);
EXPECT_EQ(flow->merge_target->branch_target, func->end_target);
}
TEST_F(IRBuilderImplTest, Switch_AllReturn) {
// {
// switch(1) {
// case 0: {
// return;
// }
// default: {
// return;
// }
// }
// if true { return; } // Dead code
// }
//
// func -> switch -> case 1
// -> default
//
// [case 1] -> func end
// [default] -> func end
// [switch merge] -> nullptr
//
auto* ast_switch =
Switch(1_i, utils::Vector{Case(utils::Vector{CaseSelector(0_i)}, Block(Return())),
DefaultCase(Block(Return()))});
auto* ast_if = If(true, Block(Return()));
WrapInFunction(ast_switch, ast_if);
auto& b = Build();
auto r = b.Build();
ASSERT_TRUE(r) << b.error();
auto m = r.Move();
ASSERT_EQ(b.FlowNodeForAstNode(ast_if), nullptr);
auto* ir_switch = b.FlowNodeForAstNode(ast_switch);
ASSERT_NE(ir_switch, nullptr);
ASSERT_TRUE(ir_switch->Is<ir::Switch>());
auto* flow = ir_switch->As<ir::Switch>();
ASSERT_NE(flow->merge_target, nullptr);
ASSERT_EQ(2u, flow->cases.Length());
ASSERT_EQ(1u, m.functions.Length());
auto* func = m.functions[0];
ASSERT_EQ(1u, flow->cases[0].selectors.Length());
ASSERT_TRUE(flow->cases[0].selectors[0]->expr->Is<ast::IntLiteralExpression>());
EXPECT_EQ(0_i, flow->cases[0].selectors[0]->expr->As<ast::IntLiteralExpression>()->value);
ASSERT_EQ(1u, flow->cases[1].selectors.Length());
EXPECT_TRUE(flow->cases[1].selectors[0]->IsDefault());
EXPECT_EQ(1u, flow->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[0].start_target->inbound_branches.Length());
EXPECT_EQ(1u, flow->cases[1].start_target->inbound_branches.Length());
EXPECT_EQ(0u, flow->merge_target->inbound_branches.Length());
EXPECT_EQ(2u, func->end_target->inbound_branches.Length());
EXPECT_EQ(func->start_target->branch_target, ir_switch);
EXPECT_EQ(flow->cases[0].start_target->branch_target, func->end_target);
EXPECT_EQ(flow->cases[1].start_target->branch_target, func->end_target);
EXPECT_EQ(flow->merge_target->branch_target, nullptr);
}
} // namespace
} // namespace tint::ir

2
src/tint/ir/switch.cc
View File

@ -18,7 +18,7 @@ TINT_INSTANTIATE_TYPEINFO(tint::ir::Switch);
namespace tint::ir {
Switch::Switch() : Base() {}
Switch::Switch(const ast::SwitchStatement* stmt) : Base(), source(stmt) {}
Switch::~Switch() = default;

23
src/tint/ir/switch.h
View File

@ -18,17 +18,38 @@
#include "src/tint/ir/block.h"
#include "src/tint/ir/flow_node.h"
// Forward declarations
namespace tint::ast {
class CaseSelector;
class SwitchStatement;
} // namespace tint::ast
namespace tint::ir {
/// Flow node representing a switch statement
class Switch : public Castable<Switch, FlowNode> {
public:
/// A case label in the struct
struct Case {
/// The case selector for this node
const utils::VectorRef<const ast::CaseSelector*> selectors;
/// The start block for the case block.
Block* start_target;
};
/// Constructor
Switch();
/// @param stmt the originating ast switch statement
explicit Switch(const ast::SwitchStatement* stmt);
~Switch() override;
/// The originating switch statment in the AST
const ast::SwitchStatement* source;
/// The switch merge target
Block* merge_target;
/// The switch case statements
utils::Vector<Case, 4> cases;
};
} // namespace tint::ir