uweigand updated this revision to Diff 276151.
uweigand added a comment.
Rebased against mainline.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D81583/new/
https://reviews.llvm.org/D81583
Files:
clang/lib/CodeGen/TargetInfo.cpp
clang/test/CodeGen/systemz-abi.cpp
Index: clang/test/CodeGen/systemz-abi.cpp
===================================================================
--- clang/test/CodeGen/systemz-abi.cpp
+++ clang/test/CodeGen/systemz-abi.cpp
@@ -23,3 +23,28 @@
// CHECK-LABEL: define void @_Z18pass_agg_float_cpp13agg_float_cpp(%struct.agg_float_cpp* noalias sret align 4 %{{.*}}, float %{{.*}})
// SOFT-FLOAT-LABEL: define void @_Z18pass_agg_float_cpp13agg_float_cpp(%struct.agg_float_cpp* noalias sret align 4 %{{.*}}, i32 %{{.*}})
+
+// A field member of empty class type in C++ makes the record nonhomogeneous,
+// unless it is marked as [[no_unique_address]];
+struct empty { };
+struct agg_nofloat_empty { float a; empty dummy; };
+struct agg_nofloat_empty pass_agg_nofloat_empty(struct agg_nofloat_empty arg) { return arg; }
+// CHECK-LABEL: define void @_Z22pass_agg_nofloat_empty17agg_nofloat_empty(%struct.agg_nofloat_empty* noalias sret align 4 %{{.*}}, i64 %{{.*}})
+// SOFT-FLOAT-LABEL: define void @_Z22pass_agg_nofloat_empty17agg_nofloat_empty(%struct.agg_nofloat_empty* noalias sret align 4 %{{.*}}, i64 %{{.*}})
+struct agg_float_empty { float a; [[no_unique_address]] empty dummy; };
+struct agg_float_empty pass_agg_float_empty(struct agg_float_empty arg) { return arg; }
+// CHECK-LABEL: define void @_Z20pass_agg_float_empty15agg_float_empty(%struct.agg_float_empty* noalias sret align 4 %{{.*}}, float %{{.*}})
+// SOFT-FLOAT-LABEL: define void @_Z20pass_agg_float_empty15agg_float_empty(%struct.agg_float_empty* noalias sret align 4 %{{.*}}, i32 %{{.*}})
+
+// And likewise for members of base classes.
+struct noemptybase { empty dummy; };
+struct agg_nofloat_emptybase : noemptybase { float a; };
+struct agg_nofloat_emptybase pass_agg_nofloat_emptybase(struct agg_nofloat_emptybase arg) { return arg; }
+// CHECK-LABEL: define void @_Z26pass_agg_nofloat_emptybase21agg_nofloat_emptybase(%struct.agg_nofloat_emptybase* noalias sret align 4 %{{.*}}, i64 %{{.*}})
+// SOFT-FLOAT-LABEL: define void @_Z26pass_agg_nofloat_emptybase21agg_nofloat_emptybase(%struct.agg_nofloat_emptybase* noalias sret align 4 %{{.*}}, i64 %{{.*}})
+struct emptybase { [[no_unique_address]] empty dummy; };
+struct agg_float_emptybase : emptybase { float a; };
+struct agg_float_emptybase pass_agg_float_emptybase(struct agg_float_emptybase arg) { return arg; }
+// CHECK-LABEL: define void @_Z24pass_agg_float_emptybase19agg_float_emptybase(%struct.agg_float_emptybase* noalias sret align 4 %{{.*}}, float %{{.*}})
+// SOFT-FLOAT-LABEL: define void @_Z24pass_agg_float_emptybase19agg_float_emptybase(%struct.agg_float_emptybase* noalias sret align 4 %{{.*}}, i32 %{{.*}})
+
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -486,12 +486,13 @@
return Ctx.getOrInsertSyncScopeID(""); /* default sync scope */
}
-static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays);
+static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays,
+ bool AllowNoUniqueAddr = false);
/// isEmptyField - Return true iff a the field is "empty", that is it
/// is an unnamed bit-field or an (array of) empty record(s).
static bool isEmptyField(ASTContext &Context, const FieldDecl *FD,
- bool AllowArrays) {
+ bool AllowArrays, bool AllowNoUniqueAddr = false) {
if (FD->isUnnamedBitfield())
return true;
@@ -514,16 +515,23 @@
//
// FIXME: We should use a predicate for whether this behavior is true in the
// current ABI.
- if (isa<CXXRecordDecl>(RT->getDecl()))
+ //
+ // The exception to the above rule are fields marked with the
+ // [[no_unique_address]] attribute (since C++20). Those do count
+ // as empty according to the Itanium ABI. This property is currently
+ // only respected if the AllowNoUniqueAddr parameter is true.
+ if (isa<CXXRecordDecl>(RT->getDecl()) &&
+ !(AllowNoUniqueAddr && FD->hasAttr<NoUniqueAddressAttr>()))
return false;
- return isEmptyRecord(Context, FT, AllowArrays);
+ return isEmptyRecord(Context, FT, AllowArrays, AllowNoUniqueAddr);
}
/// isEmptyRecord - Return true iff a structure contains only empty
/// fields. Note that a structure with a flexible array member is not
/// considered empty.
-static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays) {
+static bool isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays,
+ bool AllowNoUniqueAddr) {
const RecordType *RT = T->getAs<RecordType>();
if (!RT)
return false;
@@ -534,11 +542,11 @@
// If this is a C++ record, check the bases first.
if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD))
for (const auto &I : CXXRD->bases())
- if (!isEmptyRecord(Context, I.getType(), true))
+ if (!isEmptyRecord(Context, I.getType(), true, AllowNoUniqueAddr))
return false;
for (const auto *I : RD->fields())
- if (!isEmptyField(Context, I, AllowArrays))
+ if (!isEmptyField(Context, I, AllowArrays, AllowNoUniqueAddr))
return false;
return true;
}
@@ -7220,7 +7228,7 @@
QualType Base = I.getType();
// Empty bases don't affect things either way.
- if (isEmptyRecord(getContext(), Base, true))
+ if (isEmptyRecord(getContext(), Base, true, true))
continue;
if (!Found.isNull())
@@ -7230,12 +7238,17 @@
// Check the fields.
for (const auto *FD : RD->fields()) {
- // For compatibility with GCC, ignore empty bitfields in C++ mode.
+ // For compatibility with GCC, ignore empty bitfields in C++ mode,
+ // and empty C++ classes marked with the no_unique_address attribute.
// Unlike isSingleElementStruct(), empty structure and array fields
// do count. So do anonymous bitfields that aren't zero-sized.
- if (getContext().getLangOpts().CPlusPlus &&
- FD->isZeroLengthBitField(getContext()))
- continue;
+ if (getContext().getLangOpts().CPlusPlus) {
+ if (FD->isZeroLengthBitField(getContext()))
+ continue;
+ if (FD->hasAttr<NoUniqueAddressAttr>() &&
+ isEmptyRecord(getContext(), FD->getType(), true, true))
+ continue;
+ }
// Unlike isSingleElementStruct(), arrays do not count.
// Nested structures still do though.
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
