leonardchan updated this revision to Diff 556724.
leonardchan marked 2 inline comments as done.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D152405/new/
https://reviews.llvm.org/D152405
Files:
clang/include/clang/Basic/DiagnosticDriverKinds.td
clang/include/clang/Basic/LangOptions.def
clang/include/clang/Driver/Options.td
clang/lib/AST/VTableBuilder.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
clang/test/CodeGenCXX/OmitRTTIComponentABI/simple-vtable-definition.cpp
clang/test/CodeGenCXX/OmitRTTIComponentABI/vbase-offset.cpp
clang/test/CodeGenCXX/OmitRTTIComponentABI/vtable-layout.cpp
clang/test/Driver/omit-rtti-component-flag.cpp
clang/test/Driver/omit-rtti-component-without-no-rtti.cpp
Index: clang/test/Driver/omit-rtti-component-without-no-rtti.cpp
===================================================================
--- /dev/null
+++ clang/test/Driver/omit-rtti-component-without-no-rtti.cpp
@@ -0,0 +1,13 @@
+/// Ensure that -fexperimental-omit-vtable-rtti is only allowed if rtti is
+/// disabled.
+
+// RUN: not %clang -c -Xclang -fexperimental-omit-vtable-rtti %s 2>&1 | FileCheck -check-prefix=ERROR %s
+// RUN: not %clang -c -Xclang -fexperimental-omit-vtable-rtti -frtti %s 2>&1 | FileCheck -check-prefix=ERROR %s
+// RUN: not %clang -c -Xclang -fexperimental-omit-vtable-rtti -fno-rtti -frtti %s 2>&1 | FileCheck -check-prefix=ERROR %s
+
+// RUN: %clang -c -Xclang -fexperimental-omit-vtable-rtti -fno-rtti %s 2>&1 | FileCheck -check-prefix=NO-ERROR %s --allow-empty
+// RUN: %clang -c -Xclang -fno-experimental-omit-vtable-rtti -frtti %s 2>&1 | FileCheck -check-prefix=NO-ERROR %s --allow-empty
+// RUN: %clang -c -Xclang -fexperimental-omit-vtable-rtti -Xclang -fno-experimental-omit-vtable-rtti -frtti %s 2>&1 | FileCheck -check-prefix=NO-ERROR %s --allow-empty
+
+// ERROR: -fexperimental-omit-vtable-rtti call only be used with -fno-rtti
+// NO-ERROR-NOT: -fexperimental-omit-vtable-rtti call only be used with -fno-rtti
Index: clang/test/Driver/omit-rtti-component-flag.cpp
===================================================================
--- /dev/null
+++ clang/test/Driver/omit-rtti-component-flag.cpp
@@ -0,0 +1,5 @@
+// RUN: %clangxx --target=aarch64-unknown-linux -fno-rtti -Xclang -fexperimental-omit-vtable-rtti -c %s -### 2>&1 | FileCheck %s --check-prefix=OMIT
+// RUN: %clangxx --target=aarch64-unknown-linux -fno-rtti -Xclang -fno-experimental-omit-vtable-rtti -c %s -### 2>&1 | FileCheck %s --check-prefix=NO-OMIT
+
+// OMIT: "-fexperimental-omit-vtable-rtti"
+// NO-OMIT-NOT: "-fexperimental-omit-vtable-rtti"
Index: clang/test/CodeGenCXX/OmitRTTIComponentABI/vtable-layout.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/OmitRTTIComponentABI/vtable-layout.cpp
@@ -0,0 +1,19 @@
+/// Ensure -fdump-vtable-layout omits the rtti component when passed -fexperimental-omit-vtable-rtti.
+
+// RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fno-rtti -fexperimental-omit-vtable-rtti -emit-llvm-only -fdump-vtable-layouts | FileCheck %s
+
+// CHECK: Vtable for 'A' (2 entries).
+// CHECK-NEXT: 0 | offset_to_top (0)
+// CHECK-NEXT: -- (A, 0) vtable address --
+// CHECK-NEXT: 1 | void A::foo()
+
+class A {
+public:
+ virtual void foo();
+};
+
+void A::foo() {}
+
+void A_foo(A *a) {
+ a->foo();
+}
Index: clang/test/CodeGenCXX/OmitRTTIComponentABI/vbase-offset.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/OmitRTTIComponentABI/vbase-offset.cpp
@@ -0,0 +1,51 @@
+/// Check that the offset to top calculation is adjusted to account for the
+/// omitted RTTI entry.
+
+// RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fexperimental-omit-vtable-rtti -fno-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=POINTER %s
+// RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fexperimental-relative-c++-abi-vtables -fexperimental-omit-vtable-rtti -fno-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=RELATIVE %s
+
+/// Some important things to check:
+/// - The n16 here represents the virtual thunk size. Normally this would be 24
+/// to represent 3 components (offset to top, RTTI component, vcall offset),
+/// but since one 8-byte component is removed, this is now 16.
+// POINTER-LABEL: @_ZTv0_n16_N7Derived1fEi(
+// POINTER-NEXT: entry:
+// POINTER: [[vtable:%.+]] = load ptr, ptr %this1, align 8
+
+/// Same here - When getting the vbase offset, we subtract 2 pointer sizes
+/// instead of 3.
+// POINTER-NEXT: [[vbase_offset_ptr:%.+]] = getelementptr inbounds i8, ptr [[vtable]], i64 -16
+// POINTER-NEXT: [[vbase_offset:%.+]] = load i64, ptr [[vbase_offset_ptr]], align 8
+// POINTER-NEXT: [[adj_this:%.+]] = getelementptr inbounds i8, ptr %this1, i64 [[vbase_offset]]
+// POINTER: [[call:%.+]] = tail call noundef i32 @_ZN7Derived1fEi(ptr noundef{{[^,]*}} [[adj_this]], i32 noundef {{.*}})
+// POINTER: ret i32 [[call]]
+
+/// For relative vtables, it's almost the same except the offset sizes are
+/// halved.
+// RELATIVE-LABEL: @_ZTv0_n8_N7Derived1fEi(
+// RELATIVE-NEXT: entry:
+// RELATIVE: [[vtable:%.+]] = load ptr, ptr %this1, align 8
+// RELATIVE-NEXT: [[vbase_offset_ptr:%.+]] = getelementptr inbounds i8, ptr [[vtable]], i64 -8
+// RELATIVE-NEXT: [[vbase_offset:%.+]] = load i32, ptr [[vbase_offset_ptr]], align 4
+// RELATIVE-NEXT: [[adj_this:%.+]] = getelementptr inbounds i8, ptr %this1, i32 [[vbase_offset]]
+// RELATIVE: [[call:%.+]] = tail call noundef i32 @_ZN7Derived1fEi(ptr noundef{{[^,]*}} [[adj_this]], i32 noundef {{.*}})
+// RELATIVE: ret i32 [[call]]
+
+class Base {
+public:
+ virtual int f(int x);
+
+private:
+ long x;
+};
+
+class Derived : public virtual Base {
+public:
+ virtual int f(int x);
+
+private:
+ long y;
+};
+
+int Base::f(int x) { return x + 1; }
+int Derived::f(int x) { return x + 2; }
Index: clang/test/CodeGenCXX/OmitRTTIComponentABI/simple-vtable-definition.cpp
===================================================================
--- /dev/null
+++ clang/test/CodeGenCXX/OmitRTTIComponentABI/simple-vtable-definition.cpp
@@ -0,0 +1,32 @@
+/// Check that -fexperimental-omit-vtable-rtti omits the RTTI component from
+/// the vtable.
+
+// RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fno-rtti -fexperimental-omit-vtable-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=POINTER,RTTI %s
+// RUN: %clang_cc1 %s -triple=aarch64-unknown-linux-gnu -fexperimental-relative-c++-abi-vtables -fno-rtti -fexperimental-omit-vtable-rtti -S -o - -emit-llvm | FileCheck -check-prefixes=RELATIVE,RTTI %s
+
+/// Normally, the vtable would contain at least three components:
+/// - An offset to top
+/// - A pointer to the RTTI struct
+/// - A virtual function
+///
+/// Now vtables should have just two components.
+// POINTER: @_ZTV1A = unnamed_addr constant { [2 x ptr] } { [2 x ptr] [ptr null, ptr @_ZN1A3fooEv] }, align 8
+// RELATIVE: @_ZTV1A.local = private unnamed_addr constant { [2 x i32] } { [2 x i32] [i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr dso_local_equivalent @_ZN1A3fooEv to i64), i64 ptrtoint (ptr getelementptr inbounds ({ [2 x i32] }, ptr @_ZTV1A.local, i32 0, i32 0, i32 1) to i64)) to i32)] }, align 4
+// RELATIVE: @_ZTV1A = unnamed_addr alias { [2 x i32] }, ptr @_ZTV1A.local
+
+/// None of these supplementary symbols should be emitted with -fno-rtti, but
+/// as a sanity check lets make sure they're not emitted also.
+// RTTI-NOT: @_ZTVN10__cxxabiv117__class_type_infoE
+// RTTI-NOT: @_ZTS1A
+// RTTI-NOT: @_ZTI1A
+
+class A {
+public:
+ virtual void foo();
+};
+
+void A::foo() {}
+
+void A_foo(A *a) {
+ a->foo();
+}
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -4015,6 +4015,14 @@
options::OPT_fno_experimental_relative_cxx_abi_vtables,
TargetCXXABI::usesRelativeVTables(T));
+ // RTTI is on by default.
+ bool HasRTTI = Args.hasFlag(options::OPT_frtti, options::OPT_fno_rtti, true);
+ Opts.OmitRTTIComponent =
+ Args.hasFlag(options::OPT_fexperimental_omit_vtable_rtti,
+ options::OPT_fno_experimental_omit_vtable_rtti, false);
+ if (Opts.OmitRTTIComponent && HasRTTI)
+ Diags.Report(diag::err_drv_using_omit_rtti_component_without_no_rtti);
+
for (const auto &A : Args.getAllArgValues(OPT_fmacro_prefix_map_EQ)) {
auto Split = StringRef(A).split('=');
Opts.MacroPrefixMap.insert(
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -5526,6 +5526,9 @@
Args.AddLastArg(CmdArgs, options::OPT_fexperimental_relative_cxx_abi_vtables,
options::OPT_fno_experimental_relative_cxx_abi_vtables);
+ Args.AddLastArg(CmdArgs, options::OPT_fexperimental_omit_vtable_rtti,
+ options::OPT_fno_experimental_omit_vtable_rtti);
+
// Handle segmented stacks.
Args.addOptInFlag(CmdArgs, options::OPT_fsplit_stack,
options::OPT_fno_split_stack);
@@ -6002,6 +6005,9 @@
Args.AddLastArg(CmdArgs, options::OPT_fexperimental_relative_cxx_abi_vtables,
options::OPT_fno_experimental_relative_cxx_abi_vtables);
+ Args.AddLastArg(CmdArgs, options::OPT_fexperimental_omit_vtable_rtti,
+ options::OPT_fno_experimental_omit_vtable_rtti);
+
if (Arg *A = Args.getLastArg(options::OPT_ffuchsia_api_level_EQ))
A->render(Args, CmdArgs);
Index: clang/lib/AST/VTableBuilder.cpp
===================================================================
--- clang/lib/AST/VTableBuilder.cpp
+++ clang/lib/AST/VTableBuilder.cpp
@@ -665,7 +665,11 @@
// vtable address point. (We subtract 3 to account for the information just
// above the address point, the RTTI info, the offset to top, and the
// vcall offset itself).
- int64_t OffsetIndex = -(int64_t)(3 + Components.size());
+ size_t NumComponentsAboveAddrPoint = 3;
+ if (Context.getLangOpts().OmitRTTIComponent)
+ NumComponentsAboveAddrPoint--;
+ int64_t OffsetIndex =
+ -(int64_t)(NumComponentsAboveAddrPoint + Components.size());
// Under the relative ABI, the offset widths are 32-bit ints instead of
// pointer widths.
@@ -1669,7 +1673,8 @@
Components.push_back(VTableComponent::MakeOffsetToTop(OffsetToTop));
// Next, add the RTTI.
- Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
+ if (!Context.getLangOpts().OmitRTTIComponent)
+ Components.push_back(VTableComponent::MakeRTTI(MostDerivedClass));
uint64_t AddressPoint = Components.size();
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -2663,6 +2663,12 @@
Group<f_clang_Group>, Visibility<[ClangOption, CC1Option]>,
HelpText<"Do not use the experimental C++ class ABI for classes with virtual tables">;
+defm experimental_omit_vtable_rtti : BoolFOption<"experimental-omit-vtable-rtti",
+ LangOpts<"OmitRTTIComponent">, DefaultFalse,
+ PosFlag<SetTrue, [], [CC1Option], "Omit">,
+ NegFlag<SetFalse, [], [CC1Option], "Do not omit">,
+ BothFlags<[], [CC1Option], " the RTTI component from virtual tables">>;
+
def fcxx_abi_EQ : Joined<["-"], "fc++-abi=">,
Group<f_clang_Group>, Visibility<[ClangOption, CC1Option]>,
HelpText<"C++ ABI to use. This will override the target C++ ABI.">;
Index: clang/include/clang/Basic/LangOptions.def
===================================================================
--- clang/include/clang/Basic/LangOptions.def
+++ clang/include/clang/Basic/LangOptions.def
@@ -450,6 +450,9 @@
LANGOPT(RelativeCXXABIVTables, 1, 0,
"Use an ABI-incompatible v-table layout that uses relative references")
+LANGOPT(OmitRTTIComponent, 1, 0,
+ "Use an ABI-incompatible v-table layout that omits the RTTI component")
+
LANGOPT(VScaleMin, 32, 0, "Minimum vscale value")
LANGOPT(VScaleMax, 32, 0, "Maximum vscale value")
Index: clang/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -674,6 +674,9 @@
def err_cc1_unbounded_vscale_min : Error<
"minimum vscale must be an unsigned integer greater than 0">;
+def err_drv_using_omit_rtti_component_without_no_rtti : Error<
+ "-fexperimental-omit-vtable-rtti call only be used with -fno-rtti">;
+
def err_drv_ssp_missing_offset_argument : Error<
"'%0' is used without '-mstack-protector-guard-offset', and there is no default">;
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