transform/EmitVertexPointSize: Handle entry point parameters
Generate a new struct that contains members of the original return
type with the point size appended to it, and replace return statements
as necessary.
The SPIR-V sanitizer then special-cases this builtin when handling
entry point IO to always use a RHS which is a literal.
Fixed: tint:732
Change-Id: Id718632a5e671f3e7c82a304f5bc1fc223a6c8ee
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/49440
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: James Price <jrprice@google.com>
Auto-Submit: James Price <jrprice@google.com>
diff --git a/src/transform/emit_vertex_point_size.cc b/src/transform/emit_vertex_point_size.cc
index 9854149..13f76a0 100644
--- a/src/transform/emit_vertex_point_size.cc
+++ b/src/transform/emit_vertex_point_size.cc
@@ -14,10 +14,13 @@
#include "src/transform/emit_vertex_point_size.h"
+#include <unordered_map>
#include <utility>
-#include "src/ast/assignment_statement.h"
#include "src/program_builder.h"
+#include "src/sem/function.h"
+#include "src/sem/statement.h"
+#include "src/utils/get_or_create.h"
namespace tint {
namespace transform {
@@ -26,34 +29,85 @@
EmitVertexPointSize::~EmitVertexPointSize() = default;
Output EmitVertexPointSize::Run(const Program* in, const DataMap&) {
- if (!in->AST().Functions().HasStage(ast::PipelineStage::kVertex)) {
- // If the module doesn't have any vertex stages, then there's nothing to do.
- return Output(Program(in->Clone()));
- }
-
ProgramBuilder out;
-
CloneContext ctx(&out, in);
- Symbol pointsize = out.Symbols().New("tint_pointsize");
-
- // Declare the pointsize builtin output variable.
- out.Global(pointsize, out.ty.f32(), ast::StorageClass::kOutput, nullptr,
- ast::DecorationList{
- out.Builtin(ast::Builtin::kPointSize),
- });
-
- // Add the pointsize assignment statement to the front of all vertex stages.
- ctx.ReplaceAll([&](ast::Function* func) -> ast::Function* {
+ std::unordered_map<sem::Type*, sem::StructType*> struct_map;
+ for (auto* func : in->AST().Functions()) {
if (func->pipeline_stage() != ast::PipelineStage::kVertex) {
- return nullptr; // Just clone func
+ continue;
}
- return CloneWithStatementsAtStart(&ctx, func,
- {
- out.Assign(pointsize, 1.0f),
- });
- });
+ auto* sem_func = in->Sem().Get(func);
+
+ // Create a struct for the return type that includes a point size member.
+ auto* new_struct =
+ utils::GetOrCreate(struct_map, sem_func->ReturnType(), [&]() {
+ // Gather struct members.
+ ast::StructMemberList new_struct_members;
+ if (auto* struct_ty = sem_func->ReturnType()->As<sem::StructType>()) {
+ for (auto* member : struct_ty->impl()->members()) {
+ new_struct_members.push_back(ctx.Clone(member));
+ }
+ } else {
+ auto* ret_type = ctx.Clone(sem_func->ReturnType());
+ auto ret_type_decos = ctx.Clone(func->return_type_decorations());
+ new_struct_members.push_back(
+ out.Member("position", ret_type, std::move(ret_type_decos)));
+ }
+
+ // Append a new member for the point size.
+ new_struct_members.push_back(
+ out.Member(out.Symbols().New("tint_pointsize"), out.ty.f32(),
+ {out.Builtin(ast::Builtin::kPointSize)}));
+
+ // Create the new output struct.
+ return out.Structure(out.Sym(), new_struct_members);
+ });
+
+ // Replace return values using new output struct type constructors.
+ for (auto* ret : sem_func->ReturnStatements()) {
+ auto* ret_sem = in->Sem().Get(ret);
+
+ ast::ExpressionList new_ret_values;
+ if (auto* struct_ty = sem_func->ReturnType()->As<sem::StructType>()) {
+ std::function<ast::Expression*()> ret_value = [&]() {
+ return ctx.Clone(ret->value());
+ };
+
+ if (!ret->value()->Is<ast::IdentifierExpression>()) {
+ // Capture the original return value in a local temporary.
+ auto* new_struct_ty = ctx.Clone(struct_ty);
+ auto* temp = out.Const(out.Sym(), new_struct_ty, ret_value());
+ ctx.InsertBefore(ret_sem->Block()->statements(), ret, out.Decl(temp));
+ ret_value = [&, temp]() { return out.Expr(temp); };
+ }
+
+ for (auto* member : struct_ty->impl()->members()) {
+ auto member_sym = ctx.Clone(member->symbol());
+ new_ret_values.push_back(out.MemberAccessor(ret_value(), member_sym));
+ }
+ } else {
+ new_ret_values.push_back(ctx.Clone(ret->value()));
+ }
+
+ // Append the point size and replace the return statement.
+ new_ret_values.push_back(out.Expr(1.f));
+ ctx.Replace(ret, out.Return(ret->source(),
+ out.Construct(new_struct, new_ret_values)));
+ }
+
+ // Rewrite the function header with the new return type.
+ auto func_sym = ctx.Clone(func->symbol());
+ auto params = ctx.Clone(func->params());
+ auto* body = ctx.Clone(func->body());
+ auto decos = ctx.Clone(func->decorations());
+ auto* new_func = out.create<ast::Function>(
+ func->source(), func_sym, std::move(params), new_struct, body,
+ std::move(decos), ast::DecorationList{});
+ ctx.Replace(func, new_func);
+ }
+
ctx.Clone();
return Output(Program(std::move(out)));
diff --git a/src/transform/emit_vertex_point_size_test.cc b/src/transform/emit_vertex_point_size_test.cc
index f420115..0b70aee 100644
--- a/src/transform/emit_vertex_point_size_test.cc
+++ b/src/transform/emit_vertex_point_size_test.cc
@@ -29,7 +29,6 @@
[[stage(vertex)]]
fn entry() -> [[builtin(position)]] vec4<f32> {
- var builtin_assignments_should_happen_before_this : f32;
return vec4<f32>();
}
@@ -38,16 +37,19 @@
)";
auto* expect = R"(
-[[builtin(pointsize)]] var<out> tint_pointsize : f32;
+struct tint_symbol {
+ [[builtin(position)]]
+ position : vec4<f32>;
+ [[builtin(pointsize)]]
+ tint_pointsize : f32;
+};
fn non_entry_a() {
}
[[stage(vertex)]]
-fn entry() -> [[builtin(position)]] vec4<f32> {
- tint_pointsize = 1.0;
- var builtin_assignments_should_happen_before_this : f32;
- return vec4<f32>();
+fn entry() -> tint_symbol {
+ return tint_symbol(vec4<f32>(), 1.0);
}
fn non_entry_b() {
@@ -59,6 +61,255 @@
EXPECT_EQ(expect, str(got));
}
+TEST_F(EmitVertexPointSizeTest, VertexStageBasic_Struct) {
+ auto* src = R"(
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+fn non_entry_a() {
+}
+
+[[stage(vertex)]]
+fn entry() -> VertexOut {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return output;
+}
+
+fn non_entry_b() {
+}
+)";
+
+ auto* expect = R"(
+struct tint_symbol {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+ [[builtin(pointsize)]]
+ tint_pointsize : f32;
+};
+
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+fn non_entry_a() {
+}
+
+[[stage(vertex)]]
+fn entry() -> tint_symbol {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return tint_symbol(output.pos, output.col, 1.0);
+}
+
+fn non_entry_b() {
+}
+)";
+
+ auto got = Run<EmitVertexPointSize>(src);
+
+ EXPECT_EQ(expect, str(got));
+}
+
+// Make sure we capture the function return value in a temporary instead of
+// re-evaluating it multiple times.
+TEST_F(EmitVertexPointSizeTest, VertexStage_ReturnStructFromFunctionCall) {
+ auto* src = R"(
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+fn foo() -> VertexOut {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return output;
+}
+
+[[stage(vertex)]]
+fn entry() -> VertexOut {
+ return foo();
+}
+)";
+
+ auto* expect = R"(
+struct tint_symbol {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+ [[builtin(pointsize)]]
+ tint_pointsize : f32;
+};
+
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+fn foo() -> VertexOut {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return output;
+}
+
+[[stage(vertex)]]
+fn entry() -> tint_symbol {
+ let tint_symbol_1 : VertexOut = foo();
+ return tint_symbol(tint_symbol_1.pos, tint_symbol_1.col, 1.0);
+}
+)";
+
+ auto got = Run<EmitVertexPointSize>(src);
+
+ EXPECT_EQ(expect, str(got));
+}
+
+TEST_F(EmitVertexPointSizeTest, VertexStage_MultipleReturnStatements) {
+ auto* src = R"(
+[[stage(vertex)]]
+fn entry([[location(0)]] toggle : u32) -> [[builtin(position)]] vec4<f32> {
+ if (toggle == 1u) {
+ return vec4<f32>(0.5, 0.5, 0.5, 0.5);
+ }
+ return vec4<f32>(1.0, 1.0, 1.0, 1.0);
+}
+)";
+
+ auto* expect = R"(
+struct tint_symbol {
+ [[builtin(position)]]
+ position : vec4<f32>;
+ [[builtin(pointsize)]]
+ tint_pointsize : f32;
+};
+
+[[stage(vertex)]]
+fn entry([[location(0)]] toggle : u32) -> tint_symbol {
+ if ((toggle == 1u)) {
+ return tint_symbol(vec4<f32>(0.5, 0.5, 0.5, 0.5), 1.0);
+ }
+ return tint_symbol(vec4<f32>(1.0, 1.0, 1.0, 1.0), 1.0);
+}
+)";
+
+ auto got = Run<EmitVertexPointSize>(src);
+
+ EXPECT_EQ(expect, str(got));
+}
+
+// Test that we re-use generated structures when we've seen the original return
+// type before.
+TEST_F(EmitVertexPointSizeTest, VertexStage_MultipleShaders) {
+ auto* src = R"(
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+[[stage(vertex)]]
+fn entry1() -> [[builtin(position)]] vec4<f32> {
+ return vec4<f32>();
+}
+
+[[stage(vertex)]]
+fn entry2() -> [[builtin(position)]] vec4<f32> {
+ return vec4<f32>(1.0, 1.0, 1.0, 1.0);
+}
+
+[[stage(vertex)]]
+fn entry3() -> VertexOut {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return output;
+}
+
+[[stage(vertex)]]
+fn entry4() -> VertexOut {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.75;
+ return output;
+}
+
+)";
+
+ auto* expect = R"(
+struct tint_symbol {
+ [[builtin(position)]]
+ position : vec4<f32>;
+ [[builtin(pointsize)]]
+ tint_pointsize : f32;
+};
+
+struct tint_symbol_1 {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+ [[builtin(pointsize)]]
+ tint_pointsize_1 : f32;
+};
+
+struct VertexOut {
+ [[builtin(position)]]
+ pos : vec4<f32>;
+ [[location(0)]]
+ col : f32;
+};
+
+[[stage(vertex)]]
+fn entry1() -> tint_symbol {
+ return tint_symbol(vec4<f32>(), 1.0);
+}
+
+[[stage(vertex)]]
+fn entry2() -> tint_symbol {
+ return tint_symbol(vec4<f32>(1.0, 1.0, 1.0, 1.0), 1.0);
+}
+
+[[stage(vertex)]]
+fn entry3() -> tint_symbol_1 {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.5;
+ return tint_symbol_1(output.pos, output.col, 1.0);
+}
+
+[[stage(vertex)]]
+fn entry4() -> tint_symbol_1 {
+ var output : VertexOut;
+ output.pos = vec4<f32>();
+ output.col = 0.75;
+ return tint_symbol_1(output.pos, output.col, 1.0);
+}
+)";
+
+ auto got = Run<EmitVertexPointSize>(src);
+
+ EXPECT_EQ(expect, str(got));
+}
+
TEST_F(EmitVertexPointSizeTest, NonVertexStage) {
auto* src = R"(
[[stage(fragment)]]
@@ -87,21 +338,34 @@
TEST_F(EmitVertexPointSizeTest, AttemptSymbolCollision) {
auto* src = R"(
+struct VertexOut {
+ [[builtin(position)]]
+ tint_pointsize : vec4<f32>;
+};
+
[[stage(vertex)]]
-fn entry() -> [[builtin(position)]] vec4<f32> {
- var tint_pointsize : f32;
- return vec4<f32>();
+fn entry() -> VertexOut {
+ return VertexOut(vec4<f32>());
}
)";
auto* expect = R"(
-[[builtin(pointsize)]] var<out> tint_pointsize_1 : f32;
+struct tint_symbol {
+ [[builtin(position)]]
+ tint_pointsize : vec4<f32>;
+ [[builtin(pointsize)]]
+ tint_pointsize_1 : f32;
+};
+
+struct VertexOut {
+ [[builtin(position)]]
+ tint_pointsize : vec4<f32>;
+};
[[stage(vertex)]]
-fn entry() -> [[builtin(position)]] vec4<f32> {
- tint_pointsize_1 = 1.0;
- var tint_pointsize : f32;
- return vec4<f32>();
+fn entry() -> tint_symbol {
+ let tint_symbol_1 : VertexOut = VertexOut(vec4<f32>());
+ return tint_symbol(tint_symbol_1.tint_pointsize, 1.0);
}
)";
diff --git a/src/transform/spirv.cc b/src/transform/spirv.cc
index 47b8aa6..9166b05 100644
--- a/src/transform/spirv.cc
+++ b/src/transform/spirv.cc
@@ -321,6 +321,20 @@
ast::StorageClass::kOutput, nullptr, new_decorations);
ctx.InsertBefore(ctx.src->AST().GlobalDeclarations(), func, global_var);
+ // Special case for PointSize. The EmitVertexPointSize transform will
+ // produce a struct containing a member with the [[builtin(pointsize)]]
+ // attribute. The SPIR-V reader currently requires that a variable decorated
+ // with PointSize is assigned a _literal_ 1.0 value, so generate that
+ // assignment here to prevent the RHS from using a non-literal expression.
+ if (auto* builtin =
+ ast::GetDecoration<ast::BuiltinDecoration>(new_decorations)) {
+ if (builtin->value() == ast::Builtin::kPointSize) {
+ stores.push_back(ctx.dst->Assign(ctx.dst->Expr(global_var_symbol),
+ ctx.dst->Expr(1.f)));
+ return;
+ }
+ }
+
// Create the assignment instruction.
ast::Expression* rhs = ctx.dst->Expr(store_value);
for (auto member : member_accesses) {
diff --git a/src/writer/spirv/builder_entry_point_test.cc b/src/writer/spirv/builder_entry_point_test.cc
index ea34eb1..8874f5d 100644
--- a/src/writer/spirv/builder_entry_point_test.cc
+++ b/src/writer/spirv/builder_entry_point_test.cc
@@ -294,6 +294,99 @@
Validate(b);
}
+// Test that stores to the PointSize builtin have an RHS which is constant 1.0.
+TEST_F(BuilderTest, EntryPoint_ReturnPointSize) {
+ // struct VertexOut {
+ // [[builtin(position)]] pos : vec4<f32>;
+ // [[builtin(pointsize)]] pointsize : f32;
+ // };
+ //
+ // [[stage(vertex)]]
+ // fn vert_main() -> VertexOutput {
+ // if (false) {
+ // return VertexOutput(vec4<f32>(), 1.0);
+ // }
+ // return VertexOutput(vec4<f32>(1.0, 2.0, 3.0, 0.0), 1.0);
+ // }
+ auto vertex_out = Structure(
+ "VertexOut",
+ {
+ Member("pos", ty.vec4<f32>(), {Builtin(ast::Builtin::kPosition)}),
+ Member("pointsize", ty.f32(), {Builtin(ast::Builtin::kPointSize)}),
+ });
+ Func("vert_main", {}, vertex_out,
+ {
+ If(Expr(false), Block(Return(Construct(
+ vertex_out, Construct(ty.vec4<f32>()), 1.f)))),
+ Return(Construct(
+ vertex_out, Construct(ty.vec4<f32>(), 1.f, 2.f, 3.f, 0.f), 1.f)),
+ },
+ {Stage(ast::PipelineStage::kVertex)});
+
+ spirv::Builder& b = SanitizeAndBuild();
+
+ ASSERT_TRUE(b.Build());
+
+ EXPECT_EQ(DumpBuilder(b), R"(OpCapability Shader
+OpMemoryModel Logical GLSL450
+OpEntryPoint Vertex %18 "vert_main" %1 %6
+OpName %1 "tint_symbol_1"
+OpName %6 "tint_symbol_2"
+OpName %11 "VertexOut"
+OpMemberName %11 0 "pos"
+OpMemberName %11 1 "pointsize"
+OpName %12 "tint_symbol_3"
+OpName %13 "tint_symbol"
+OpName %18 "vert_main"
+OpDecorate %1 BuiltIn Position
+OpDecorate %6 BuiltIn PointSize
+OpMemberDecorate %11 0 Offset 0
+OpMemberDecorate %11 1 Offset 16
+%4 = OpTypeFloat 32
+%3 = OpTypeVector %4 4
+%2 = OpTypePointer Output %3
+%5 = OpConstantNull %3
+%1 = OpVariable %2 Output %5
+%7 = OpTypePointer Output %4
+%8 = OpConstantNull %4
+%6 = OpVariable %7 Output %8
+%10 = OpTypeVoid
+%11 = OpTypeStruct %3 %4
+%9 = OpTypeFunction %10 %11
+%16 = OpConstant %4 1
+%17 = OpTypeFunction %10
+%20 = OpTypeBool
+%21 = OpConstantFalse %20
+%25 = OpConstantComposite %11 %5 %16
+%27 = OpConstant %4 2
+%28 = OpConstant %4 3
+%29 = OpConstant %4 0
+%30 = OpConstantComposite %3 %16 %27 %28 %29
+%31 = OpConstantComposite %11 %30 %16
+%12 = OpFunction %10 None %9
+%13 = OpFunctionParameter %11
+%14 = OpLabel
+%15 = OpCompositeExtract %3 %13 0
+OpStore %1 %15
+OpStore %6 %16
+OpReturn
+OpFunctionEnd
+%18 = OpFunction %10 None %17
+%19 = OpLabel
+OpSelectionMerge %22 None
+OpBranchConditional %21 %23 %22
+%23 = OpLabel
+%24 = OpFunctionCall %10 %12 %25
+OpReturn
+%22 = OpLabel
+%26 = OpFunctionCall %10 %12 %31
+OpReturn
+OpFunctionEnd
+)");
+
+ Validate(b);
+}
+
} // namespace
} // namespace spirv
} // namespace writer
