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[HLSL] Forward arguments in BuiltinTypeMethodBuilder::callBuiltin. NFC #117789

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merged 2 commits into from
Nov 26, 2024
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[HLSL] Forward arguments in BuiltinTypeMethodBuilder::callBuiltin. NFC #117789

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3b3e3bc
[HLSL] Forward arguments in BuiltinTypeMethodBuilder::callBuiltin. NFC
bogner Nov 26, 2024
a292f57
fixup: Use array, Fix comment
bogner Nov 26, 2024
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60 changes: 38 additions & 22 deletions clang/lib/Sema/HLSLExternalSemaSource.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -455,7 +455,7 @@ struct TemplateParameterListBuilder {
//
// BuiltinTypeMethodBuilder(Sema, RecordBuilder, "MethodName", ReturnType)
// .addParam("param_name", Type, InOutModifier)
// .callBuiltin("buildin_name", { BuiltinParams })
// .callBuiltin("buildin_name", BuiltinParams... )
// .finalizeMethod();
//
// The builder needs to have all of the method parameters before it can create
Expand All @@ -465,9 +465,9 @@ struct TemplateParameterListBuilder {
// referenced from the body building methods. Destructor or an explicit call to
// finalizeMethod() will complete the method definition.
//
// The callBuiltin helper method passes in the resource handle as the first
// argument of the builtin call. If this is not desired it takes a bool flag to
// disable this.
// The callBuiltin helper method accepts constants via `Expr *` or placeholder
// value arguments to indicate which function arguments to forward to the
// builtin.
//
// If the method that is being built has a non-void return type the
// finalizeMethod will create a return statent with the value of the last
Expand All @@ -489,6 +489,24 @@ struct BuiltinTypeMethodBuilder {
llvm::SmallVector<MethodParam> Params;
llvm::SmallVector<Stmt *> StmtsList;

// Argument placeholders, inspired by std::placeholder. These are the indices
// of arguments to forward to `callBuiltin`, and additionally `Handle` which
// refers to the resource handle.
enum class PlaceHolder { _0, _1, _2, _3, Handle = 127 };

Expr *convertPlaceholder(PlaceHolder PH) {
if (PH == PlaceHolder::Handle)
return getResourceHandleExpr();

ASTContext &AST = DeclBuilder.SemaRef.getASTContext();
ParmVarDecl *ParamDecl = Method->getParamDecl(static_cast<unsigned>(PH));
return DeclRefExpr::Create(
AST, NestedNameSpecifierLoc(), SourceLocation(), ParamDecl, false,
DeclarationNameInfo(ParamDecl->getDeclName(), SourceLocation()),
ParamDecl->getType(), VK_PRValue);
}
Expr *convertPlaceholder(Expr *E) { return E; }

public:
BuiltinTypeMethodBuilder(Sema &S, BuiltinTypeDeclBuilder &DB, StringRef Name,
QualType ReturnTy)
Expand All @@ -502,7 +520,10 @@ struct BuiltinTypeMethodBuilder {
HLSLParamModifierAttr::Spelling Modifier =
HLSLParamModifierAttr::Keyword_in) {
assert(Method == nullptr && "Cannot add param, method already created");
llvm_unreachable("not yet implemented");
const IdentifierInfo &II = DeclBuilder.SemaRef.getASTContext().Idents.get(
Name, tok::TokenKind::identifier);
Params.emplace_back(II, Ty, Modifier);
return *this;
}

private:
Expand Down Expand Up @@ -564,9 +585,9 @@ struct BuiltinTypeMethodBuilder {
OK_Ordinary);
}

BuiltinTypeMethodBuilder &
callBuiltin(StringRef BuiltinName, ArrayRef<Expr *> CallParms,
bool AddResourceHandleAsFirstArg = true) {
template <typename... Ts>
BuiltinTypeMethodBuilder &callBuiltin(StringRef BuiltinName, Ts... ArgSpecs) {
SmallVector<Expr *> Args{convertPlaceholder(std::forward<Ts>(ArgSpecs))...};
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@damyanp damyanp Nov 26, 2024

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Is SmallVector smart enough for this to evaporate into being a stack allocated array, or is there a chance that it might make a heap allocation to store the args?

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@tex3d tex3d Nov 26, 2024

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Yes, SmallVector will have stack allocated storage. Its size is derived from the initialization, which is dependent on the number of ArgSpecs.

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@bogner bogner Nov 26, 2024

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This raises a good point though - I'll change this to just use std::array here since we know the exact size at compile time.


// The first statement added to a method or access to 'this` creates the
// declaration.
Expand All @@ -579,16 +600,9 @@ struct BuiltinTypeMethodBuilder {
AST, NestedNameSpecifierLoc(), SourceLocation(), FD, false,
FD->getNameInfo(), FD->getType(), VK_PRValue);

SmallVector<Expr *> NewCallParms;
if (AddResourceHandleAsFirstArg) {
NewCallParms.push_back(getResourceHandleExpr());
for (auto *P : CallParms)
NewCallParms.push_back(P);
}

Expr *Call = CallExpr::Create(
AST, DRE, AddResourceHandleAsFirstArg ? NewCallParms : CallParms,
FD->getReturnType(), VK_PRValue, SourceLocation(), FPOptionsOverride());
Expr *Call =
CallExpr::Create(AST, DRE, Args, FD->getReturnType(), VK_PRValue,
SourceLocation(), FPOptionsOverride());
StmtsList.push_back(Call);
return *this;
}
Expand Down Expand Up @@ -656,18 +670,20 @@ BuiltinTypeDeclBuilder::addSimpleTemplateParams(ArrayRef<StringRef> Names,
}

BuiltinTypeDeclBuilder &BuiltinTypeDeclBuilder::addIncrementCounterMethod() {
using PH = BuiltinTypeMethodBuilder::PlaceHolder;
return BuiltinTypeMethodBuilder(SemaRef, *this, "IncrementCounter",
SemaRef.getASTContext().UnsignedIntTy)
.callBuiltin("__builtin_hlsl_buffer_update_counter",
{getConstantIntExpr(1)})
.callBuiltin("__builtin_hlsl_buffer_update_counter", PH::Handle,
getConstantIntExpr(1))
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@damyanp damyanp Nov 26, 2024

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How evil would it be to add a Expr *convertPlaceholder(int) that does the getConstantIntExpr for you, so this could be written as: .callBuiltin("__builtin_hlsl_buffer_update_conter", PH::Handle, 1)?

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@bogner bogner Nov 26, 2024

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This feels too magical to me (and also it introduces an annoying ambiguity with a literal zero - is it an int or a null Expr *?)

.finalizeMethod();
}

BuiltinTypeDeclBuilder &BuiltinTypeDeclBuilder::addDecrementCounterMethod() {
using PH = BuiltinTypeMethodBuilder::PlaceHolder;
return BuiltinTypeMethodBuilder(SemaRef, *this, "DecrementCounter",
SemaRef.getASTContext().UnsignedIntTy)
.callBuiltin("__builtin_hlsl_buffer_update_counter",
{getConstantIntExpr(-1)})
.callBuiltin("__builtin_hlsl_buffer_update_counter", PH::Handle,
getConstantIntExpr(-1))
.finalizeMethod();
}

Expand Down