ahatanak updated this revision to Diff 198716.
ahatanak marked 3 inline comments as done.
ahatanak edited the summary of this revision.
ahatanak added a comment.
Move the code that was in `AlignedExceptionObject.h` to `getExnObjectAlignment`
and remove the header.
Repository:
rC Clang
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D61667/new/
https://reviews.llvm.org/D61667
Files:
include/clang/Basic/DiagnosticGroups.td
include/clang/Basic/DiagnosticSemaKinds.td
include/clang/Basic/TargetInfo.h
lib/Basic/Targets/OSTargets.h
lib/CodeGen/ItaniumCXXABI.cpp
lib/Sema/SemaExprCXX.cpp
test/CodeGenCXX/eh.cpp
test/SemaCXX/warn-overaligned-type-thrown.cpp
Index: test/SemaCXX/warn-overaligned-type-thrown.cpp
===================================================================
--- /dev/null
+++ test/SemaCXX/warn-overaligned-type-thrown.cpp
@@ -0,0 +1,53 @@
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.13.99 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions -DUNDERALIGNED %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions -Wno-underaligned-exception-object -DNODIAG %s
+
+struct S0 {
+ S0();
+ int m;
+};
+
+struct Overaligned1 {
+ Overaligned1();
+ int __attribute__((aligned(16))) m;
+};
+
+struct __attribute__((aligned(16))) Overaligned2 {
+ Overaligned2();
+ int m;
+};
+
+struct Overaligned3 {
+ Overaligned3();
+ int __attribute__((aligned(64))) m;
+};
+
+void test0() {
+ throw S0();
+}
+
+void test1() {
+ throw Overaligned1();
+}
+
+void test2() {
+ throw Overaligned2();
+}
+
+void test3() {
+ throw Overaligned3();
+}
+
+#if defined(NODIAG)
+// expected-no-diagnostics
+#elif defined(UNDERALIGNED)
+// expected-warning@-14 {{underaligned exception object thrown}}
+// expected-note@-15 {{(16-bytes) is larger than the guaranteed alignment of the memory Itanium C++ runtime returns (8-bytes)}}
+// expected-warning@-12 {{underaligned exception object thrown}}
+// expected-note@-13 {{(16-bytes) is larger than the guaranteed alignment of the memory Itanium C++ runtime returns (8-bytes)}}
+// expected-warning@-10 {{underaligned exception object thrown}}
+// expected-note@-11 {{(64-bytes) is larger than the guaranteed alignment of the memory Itanium C++ runtime returns (8-bytes)}}
+#else
+// expected-warning@-13 {{underaligned exception object thrown}}
+// expected-note@-14 {{(64-bytes) is larger than the guaranteed alignment of the memory Itanium C++ runtime returns (16-bytes)}}
+#endif
Index: test/CodeGenCXX/eh.cpp
===================================================================
--- test/CodeGenCXX/eh.cpp
+++ test/CodeGenCXX/eh.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -triple x86_64-apple-darwin -std=c++11 -emit-llvm %s -o - \
-// RUN: | FileCheck %s
+// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -triple x86_64-apple-macosx10.13.99 -std=c++11 -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=UNALIGNED %s
+// RUN: %clang_cc1 -fcxx-exceptions -fexceptions -triple x86_64-apple-macosx10.14 -std=c++11 -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ALIGNED %s
struct test1_D {
double d;
@@ -13,7 +13,8 @@
// CHECK: [[EXNOBJ:%.*]] = call i8* @__cxa_allocate_exception(i64 8)
// CHECK-NEXT: [[EXN:%.*]] = bitcast i8* [[EXNOBJ]] to [[DSTAR:%[^*]*\*]]
// CHECK-NEXT: [[EXN2:%.*]] = bitcast [[DSTAR]] [[EXN]] to i8*
-// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 16 [[EXN2]], i8* align 8 bitcast ([[DSTAR]] @d1 to i8*), i64 8, i1 false)
+// UNALIGNED-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 8 [[EXN2]], i8* align 8 bitcast ([[DSTAR]] @d1 to i8*), i64 8, i1 false)
+// ALIGNED-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 16 [[EXN2]], i8* align 8 bitcast ([[DSTAR]] @d1 to i8*), i64 8, i1 false)
// CHECK-NEXT: call void @__cxa_throw(i8* [[EXNOBJ]], i8* bitcast ({ i8*, i8* }* @_ZTI7test1_D to i8*), i8* null) [[NR:#[0-9]+]]
// CHECK-NEXT: unreachable
@@ -466,7 +467,8 @@
// CHECK: [[T0:%.*]] = call i8* @__cxa_allocate_exception(i64 16)
// CHECK-NEXT: [[T1:%.*]] = bitcast i8* [[T0]] to %"class.test17::DerivedException"*
// CHECK-NEXT: [[T2:%.*]] = bitcast %"class.test17::DerivedException"* [[T1]] to i8*
- // CHECK-NEXT: call void @llvm.memset.p0i8.i64(i8* align 16 [[T2]], i8 0, i64 16, i1 false)
+ // UNALIGNED-NEXT: call void @llvm.memset.p0i8.i64(i8* align 8 [[T2]], i8 0, i64 16, i1 false)
+ // ALIGNED-NEXT: call void @llvm.memset.p0i8.i64(i8* align 16 [[T2]], i8 0, i64 16, i1 false)
}
}
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -941,6 +941,20 @@
}
}
+ // Issue a warning if the type of the thrown object requires an alignment that
+ // is larger than the minimum alignment the libc++abi runtime guarantees.
+ if (Context.getTargetInfo().getTriple().isOSDarwin()) {
+ CharUnits TypeAlign = Context.getTypeAlignInChars(Ty);
+ CharUnits ExnObjAlign = Context.toCharUnitsFromBits(
+ Context.getTargetInfo().getExnObjectAlignment());
+ if (ExnObjAlign < TypeAlign) {
+ Diag(ThrowLoc, diag::warn_throw_underaligned_obj);
+ Diag(ThrowLoc, diag::note_throw_underaligned_obj)
+ << Ty << (unsigned)TypeAlign.getQuantity()
+ << (unsigned)ExnObjAlign.getQuantity();
+ }
+ }
+
return false;
}
Index: lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- lib/CodeGen/ItaniumCXXABI.cpp
+++ lib/CodeGen/ItaniumCXXABI.cpp
@@ -154,17 +154,9 @@
Address Ptr, QualType ElementType,
const CXXDestructorDecl *Dtor) override;
- /// Itanium says that an _Unwind_Exception has to be "double-word"
- /// aligned (and thus the end of it is also so-aligned), meaning 16
- /// bytes. Of course, that was written for the actual Itanium,
- /// which is a 64-bit platform. Classically, the ABI doesn't really
- /// specify the alignment on other platforms, but in practice
- /// libUnwind declares the struct with __attribute__((aligned)), so
- /// we assume that alignment here. (It's generally 16 bytes, but
- /// some targets overwrite it.)
CharUnits getAlignmentOfExnObject() {
- auto align = CGM.getContext().getTargetDefaultAlignForAttributeAligned();
- return CGM.getContext().toCharUnitsFromBits(align);
+ unsigned Align = CGM.getContext().getTargetInfo().getExnObjectAlignment();
+ return CGM.getContext().toCharUnitsFromBits(Align);
}
void emitRethrow(CodeGenFunction &CGF, bool isNoReturn) override;
Index: lib/Basic/Targets/OSTargets.h
===================================================================
--- lib/Basic/Targets/OSTargets.h
+++ lib/Basic/Targets/OSTargets.h
@@ -133,6 +133,37 @@
/// attribute on declarations that can be dynamically replaced.
bool hasProtectedVisibility() const override { return false; }
+ unsigned getExnObjectAlignment() const override {
+ // Older versions of libc++abi guarantee an alignment of only 8-bytes for
+ // exception objects because of a bug in __cxa_exception that was
+ // eventually fixed in r319123.
+ llvm::VersionTuple MinVersion;
+ const llvm::Triple &T = this->getTriple();
+
+ // Compute the earliest OS versions that have the fix to libc++abi.
+ switch (T.getOS()) {
+ case llvm::Triple::Darwin:
+ case llvm::Triple::MacOSX: // Earliest supporting version is 10.14.
+ MinVersion = llvm::VersionTuple(10U, 14U);
+ break;
+ case llvm::Triple::IOS:
+ case llvm::Triple::TvOS: // Earliest supporting version is 12.0.0.
+ MinVersion = llvm::VersionTuple(12U);
+ break;
+ case llvm::Triple::WatchOS: // Earliest supporting version is 5.0.0.
+ MinVersion = llvm::VersionTuple(5U);
+ break;
+ default:
+ llvm_unreachable("Unexpected OS");
+ }
+
+ unsigned Major, Minor, Micro;
+ T.getOSVersion(Major, Minor, Micro);
+ if (llvm::VersionTuple(Major, Minor, Micro) < MinVersion)
+ return 64;
+ return OSTargetInfo<Target>::getExnObjectAlignment();
+ }
+
TargetInfo::IntType getLeastIntTypeByWidth(unsigned BitWidth,
bool IsSigned) const final {
// Darwin uses `long long` for `int_least64_t` and `int_fast64_t`.
Index: include/clang/Basic/TargetInfo.h
===================================================================
--- include/clang/Basic/TargetInfo.h
+++ include/clang/Basic/TargetInfo.h
@@ -637,6 +637,21 @@
/// types for the given target.
unsigned getSimdDefaultAlign() const { return SimdDefaultAlign; }
+ /// Return the alignment (in bits) of the thrown exception object. This is
+ /// only meaningful for targets that allocate C++ exceptions in a system
+ /// runtime, such as those using the Itanium C++ ABI.
+ virtual unsigned getExnObjectAlignment() const {
+ // Itanium says that an _Unwind_Exception has to be "double-word"
+ // aligned (and thus the end of it is also so-aligned), meaning 16
+ // bytes. Of course, that was written for the actual Itanium,
+ // which is a 64-bit platform. Classically, the ABI doesn't really
+ // specify the alignment on other platforms, but in practice
+ // libUnwind declares the struct with __attribute__((aligned)), so
+ // we assume that alignment here. (It's generally 16 bytes, but
+ // some targets overwrite it.)
+ return getDefaultAlignForAttributeAligned();
+ }
+
/// Return the size of intmax_t and uintmax_t for this target, in bits.
unsigned getIntMaxTWidth() const {
return getTypeWidth(IntMaxType);
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -6564,6 +6564,12 @@
"cannot throw object of incomplete type %0">;
def err_throw_incomplete_ptr : Error<
"cannot throw pointer to object of incomplete type %0">;
+def warn_throw_underaligned_obj : Warning<
+ "underaligned exception object thrown">,
+ InGroup<UnderalignedExcpObj>;
+def note_throw_underaligned_obj : Note<
+ "The alignment of %0 (%1-bytes) is larger than the guaranteed alignment of "
+ "the memory Itanium C++ runtime returns (%2-bytes)">;
def err_return_in_constructor_handler : Error<
"return in the catch of a function try block of a constructor is illegal">;
def warn_cdtor_function_try_handler_mem_expr : Warning<
Index: include/clang/Basic/DiagnosticGroups.td
===================================================================
--- include/clang/Basic/DiagnosticGroups.td
+++ include/clang/Basic/DiagnosticGroups.td
@@ -408,6 +408,7 @@
def ObjCFlexibleArray : DiagGroup<"objc-flexible-array">;
def ObjCBoxing : DiagGroup<"objc-boxing">;
def OpenCLUnsupportedRGBA: DiagGroup<"opencl-unsupported-rgba">;
+def UnderalignedExcpObj : DiagGroup<"underaligned-exception-object">;
def DeprecatedObjCIsaUsage : DiagGroup<"deprecated-objc-isa-usage">;
def ExplicitInitializeCall : DiagGroup<"explicit-initialize-call">;
def Packed : DiagGroup<"packed">;
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