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[MS ABI] nullptr data member ptrs are mangled differently for classes vs fns 

It turns out that nullptr pointers to data members act differently in
function templates vs class templates.  Class templates use a variable
width representation proportional to the number of fields needed to
materialize it.  Function templates always use a single '0' template
parameter.  However, using '0' all the time is problematic if the class
uses single or multiple inheritance.  In those cases, use -1.

llvm-svn: 241251
This commit is contained in:
David Majnemer 2015-07-02 09:43:11 +00:00
parent 0912de3216
commit 1023668bc2
3 changed files with 32 additions and 5 deletions
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18
clang/lib/AST/MicrosoftMangle.cpp
View File

@ -1215,11 +1215,23 @@ void MicrosoftCXXNameMangler::mangleTemplateArg(const TemplateDecl *TD,
return;
}
if (MPT->isMemberDataPointer()) {
mangleMemberDataPointer(RD, nullptr);
return;
if (isa<ClassTemplateDecl>(TD)) {
mangleMemberDataPointer(RD, nullptr);
return;
}
// nullptr data pointers are always represented with a single field
// which is initialized with either 0 or -1. Why -1? Well, we need to
// distinguish the case where the data member is at offset zero in the
// record.
// However, we are free to use 0 *if* we would use multiple fields for
// non-nullptr member pointers.
if (!RD->nullFieldOffsetIsZero()) {
mangleIntegerLiteral(llvm::APSInt::get(-1), /*IsBoolean=*/false);
return;
}
}
}
Out << "$0A@";
mangleIntegerLiteral(llvm::APSInt::getUnsigned(0), /*IsBoolean=*/false);
break;
}
case TemplateArgument::Expression:

15
clang/test/CodeGenCXX/mangle-ms-templates-memptrs-2.cpp
View File

@ -3,22 +3,37 @@
template <typename T, int (T::*)() = nullptr>
struct J {};
template <typename T, int T::* = nullptr>
struct K {};
struct __single_inheritance M;
J<M> m;
// CHECK-DAG: @"\01?m@@3U?$J@UM@@$0A@@@A"
K<M> m2;
// CHECK-DAG: @"\01?m2@@3U?$K@UM@@$0?0@@A"
struct __multiple_inheritance N;
J<N> n;
// CHECK-DAG: @"\01?n@@3U?$J@UN@@$HA@@@A"
K<N> n2;
// CHECK-DAG: @"\01?n2@@3U?$K@UN@@$0?0@@A"
struct __virtual_inheritance O;
J<O> o;
// CHECK-DAG: @"\01?o@@3U?$J@UO@@$IA@A@@@A"
K<O> o2;
// CHECK-DAG: @"\01?o2@@3U?$K@UO@@$FA@?0@@A"
struct P;
J<P> p;
// CHECK-DAG: @"\01?p@@3U?$J@UP@@$JA@A@?0@@A"
K<P> p2;
// CHECK-DAG: @"\01?p2@@3U?$K@UP@@$GA@A@?0@@A"
#pragma pointers_to_members(full_generality, virtual_inheritance)
struct S {

4
clang/test/CodeGenCXX/mangle-ms-templates-memptrs.cpp
View File

@ -69,8 +69,8 @@ void ReadFields() {
// them right in class templates.
// CHECK: call {{.*}} @"\01??$ReadField@US@@$0A@@@YAHAAUS@@@Z"
// CHECK: call {{.*}} @"\01??$ReadField@UM@@$0A@@@YAHAAUM@@@Z"
// CHECK: call {{.*}} @"\01??$ReadField@UV@@$FA@?0@@YAHAAUV@@@Z"
// CHECK: call {{.*}} @"\01??$ReadField@UU@@$GA@A@?0@@YAHAAUU@@@Z"
// CHECK: call {{.*}} @"\01??$ReadField@UV@@$0A@@@YAHAAUV@@@Z"
// CHECK: call {{.*}} @"\01??$ReadField@UU@@$0A@@@YAHAAUU@@@Z"
// Non-polymorphic null data memptr vs first field memptr. MSVC mangles these
// the same.