[Sema] Implement __make_integer_seq
This new builtin template allows for incredibly fast instantiations of
templates like std::integer_sequence.
Performance numbers follow:
My work station has 64 GB of ram + 20 Xeon Cores at 2.8 GHz.
__make_integer_seq<std::integer_sequence, int, 90000> takes 0.25
seconds.
std::make_integer_sequence<int, 90000> takes unbound time, it is still
running. Clang is consuming gigabytes of memory.
Differential Revision: http://reviews.llvm.org/D13786
llvm-svn: 252036
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index 0ba34ea..66cfada 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -627,6 +627,11 @@
R.addDecl(S.getASTContext().getFloat128StubType());
return true;
}
+ if (S.getLangOpts().CPlusPlus && NameKind == Sema::LookupOrdinaryName &&
+ II == S.getASTContext().getMakeIntegerSeqName()) {
+ R.addDecl(S.getASTContext().getMakeIntegerSeqDecl());
+ return true;
+ }
// If this is a builtin on this (or all) targets, create the decl.
if (unsigned BuiltinID = II->getBuiltinID()) {
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index de89ce1..8821088 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -18,6 +18,7 @@
#include "clang/AST/ExprCXX.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/TypeVisitor.h"
+#include "clang/Basic/Builtins.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/TargetInfo.h"
@@ -208,7 +209,8 @@
R.suppressDiagnostics();
} else {
assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
- isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD));
+ isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
+ isa<BuiltinTemplateDecl>(TD));
TemplateKind =
isa<VarTemplateDecl>(TD) ? TNK_Var_template : TNK_Type_template;
}
@@ -2017,6 +2019,58 @@
}
}
+static QualType
+checkBuiltinTemplateIdType(Sema &SemaRef, BuiltinTemplateDecl *BTD,
+ const SmallVectorImpl<TemplateArgument> &Converted,
+ SourceLocation TemplateLoc,
+ TemplateArgumentListInfo &TemplateArgs) {
+ ASTContext &Context = SemaRef.getASTContext();
+ switch (BTD->getBuiltinTemplateKind()) {
+ case BTK__make_integer_seq:
+ // Specializations of __make_integer_seq<S, T, N> are treated like
+ // S<T, 0, ..., N-1>.
+
+ // C++14 [inteseq.intseq]p1:
+ // T shall be an integer type.
+ if (!Converted[1].getAsType()->isIntegralType(Context)) {
+ SemaRef.Diag(TemplateArgs[1].getLocation(),
+ diag::err_integer_sequence_integral_element_type);
+ return QualType();
+ }
+
+ // C++14 [inteseq.make]p1:
+ // If N is negative the program is ill-formed.
+ TemplateArgument NumArgsArg = Converted[2];
+ llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
+ if (NumArgs < 0) {
+ SemaRef.Diag(TemplateArgs[2].getLocation(),
+ diag::err_integer_sequence_negative_length);
+ return QualType();
+ }
+
+ QualType ArgTy = NumArgsArg.getIntegralType();
+ TemplateArgumentListInfo SyntheticTemplateArgs;
+ // The type argument gets reused as the first template argument in the
+ // synthetic template argument list.
+ SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
+ // Expand N into 0 ... N-1.
+ for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
+ I < NumArgs; ++I) {
+ TemplateArgument TA(Context, I, ArgTy);
+ Expr *E = SemaRef.BuildExpressionFromIntegralTemplateArgument(
+ TA, TemplateArgs[2].getLocation())
+ .getAs<Expr>();
+ SyntheticTemplateArgs.addArgument(
+ TemplateArgumentLoc(TemplateArgument(E), E));
+ }
+ // The first template argument will be reused as the template decl that
+ // our synthetic template arguments will be applied to.
+ return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
+ TemplateLoc, SyntheticTemplateArgs);
+ }
+ llvm_unreachable("unexpected BuiltinTemplateDecl!");
+}
+
QualType Sema::CheckTemplateIdType(TemplateName Name,
SourceLocation TemplateLoc,
TemplateArgumentListInfo &TemplateArgs) {
@@ -2171,6 +2225,9 @@
CanonType = Context.getTypeDeclType(Decl);
assert(isa<RecordType>(CanonType) &&
"type of non-dependent specialization is not a RecordType");
+ } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
+ CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
+ TemplateArgs);
}
// Build the fully-sugared type for this class template
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 1789855..f5f03d0 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -922,6 +922,11 @@
llvm_unreachable("EnumConstantDecls can only occur within EnumDecls.");
}
+Decl *
+TemplateDeclInstantiator::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
+ llvm_unreachable("BuiltinTemplateDecls cannot be instantiated.");
+}
+
Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
bool isFriend = (D->getFriendObjectKind() != Decl::FOK_None);