[clang] [clang][Builtins] Parse clang extended vectors types. (PR #83584)
Francesco Petrogalli via cfe-commits
cfe-commits at lists.llvm.org
Fri Mar 1 07:46:43 PST 2024
https://github.com/fpetrogalli updated https://github.com/llvm/llvm-project/pull/83584
>From 2b4d67bf59d609321701540a15f48eda04688652 Mon Sep 17 00:00:00 2001
From: Vinayak Dev <104419489+vinayakdsci at users.noreply.github.com>
Date: Fri, 1 Mar 2024 21:10:46 +0530
Subject: [PATCH 1/3] [Clang][Sema]: Allow copy constructor side effects
(#81127)
Copy constructors can have initialization with side effects, and thus
clang should not emit a warning when -Wunused-variable is used in this
context. Currently however, a warning is emitted.
Now, compilation happens without warnings.
Fixes #79518
---
clang/docs/ReleaseNotes.rst | 4 +++
clang/lib/Sema/SemaDecl.cpp | 3 +-
clang/test/SemaCXX/warn-unused-variables.cpp | 33 ++++++++++++++++++--
3 files changed, 37 insertions(+), 3 deletions(-)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 1286263700963c..cfe0ac6a5dca61 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -218,6 +218,10 @@ Bug Fixes in This Version
for logical operators in C23.
Fixes (`#64356 <https://github.com/llvm/llvm-project/issues/64356>`_).
+- Clang no longer produces a false-positive `-Wunused-variable` warning
+ for variables created through copy initialization having side-effects in C++17 and later.
+ Fixes (`#79518 <https://github.com/llvm/llvm-project/issues/79518>`_).
+
Bug Fixes to Compiler Builtins
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 9fdd8eb236d1ee..6289cf75e17413 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2044,7 +2044,8 @@ static bool ShouldDiagnoseUnusedDecl(const LangOptions &LangOpts,
return false;
if (Init) {
- const auto *Construct = dyn_cast<CXXConstructExpr>(Init);
+ const auto *Construct =
+ dyn_cast<CXXConstructExpr>(Init->IgnoreImpCasts());
if (Construct && !Construct->isElidable()) {
const CXXConstructorDecl *CD = Construct->getConstructor();
if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>() &&
diff --git a/clang/test/SemaCXX/warn-unused-variables.cpp b/clang/test/SemaCXX/warn-unused-variables.cpp
index b649c7d8089355..29e8d08d37d8c6 100644
--- a/clang/test/SemaCXX/warn-unused-variables.cpp
+++ b/clang/test/SemaCXX/warn-unused-variables.cpp
@@ -1,5 +1,7 @@
// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify %s
-// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify -std=gnu++11 %s
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify=expected,cxx98-14 -std=gnu++11 %s
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify=expected,cxx98-14 -std=gnu++14 %s
+// RUN: %clang_cc1 -fsyntax-only -Wunused-variable -Wunused-label -Wno-c++1y-extensions -verify -std=gnu++17 %s
template<typename T> void f() {
T t;
t = 17;
@@ -183,7 +185,8 @@ void foo(int size) {
NonTriviallyDestructible array[2]; // no warning
NonTriviallyDestructible nestedArray[2][2]; // no warning
- Foo fooScalar = 1; // expected-warning {{unused variable 'fooScalar'}}
+ // Copy initialzation gives warning before C++17
+ Foo fooScalar = 1; // cxx98-14-warning {{unused variable 'fooScalar'}}
Foo fooArray[] = {1,2}; // expected-warning {{unused variable 'fooArray'}}
Foo fooNested[2][2] = { {1,2}, {3,4} }; // expected-warning {{unused variable 'fooNested'}}
}
@@ -297,3 +300,29 @@ void RAIIWrapperTest() {
}
} // namespace gh54489
+
+// Ensure that -Wunused-variable does not emit warning
+// on copy constructors with side effects (C++17 and later)
+#if __cplusplus >= 201703L
+namespace gh79518 {
+
+struct S {
+ S(int);
+};
+
+// With an initializer list
+struct A {
+ int x;
+ A(int x) : x(x) {}
+};
+
+void foo() {
+ S s(0); // no warning
+ S s2 = 0; // no warning
+ S s3{0}; // no warning
+
+ A a = 1; // no warning
+}
+
+} // namespace gh79518
+#endif
>From 9cd3e17192833e2cbafed55b649307ead32dcc3e Mon Sep 17 00:00:00 2001
From: Francesco Petrogalli <francesco.petrogalli at apple.com>
Date: Fri, 1 Mar 2024 16:23:57 +0100
Subject: [PATCH 2/3] [clang][Builtins] Parse clang extended vectors types.
Clang extended vector types are mangled as follows:
ext_vector_type_<lanes>_<scalar type>
This is used to defetmine the builtins signature for builtins that
use parmeters defined as
typedef <scalar type> ext_vector_type_<lanes>_<scalar type> __attribute__((ext_vector_type(<lanes>)))
For example:
typedef double ext_vector_type_4_double __attribute__((ext_vector_type(4)))
---
.../target-builtins-prototype-parser.td | 20 +++++++++++++++++++
clang/utils/TableGen/ClangBuiltinsEmitter.cpp | 10 ++++++++++
2 files changed, 30 insertions(+)
create mode 100644 clang/test/TableGen/target-builtins-prototype-parser.td
diff --git a/clang/test/TableGen/target-builtins-prototype-parser.td b/clang/test/TableGen/target-builtins-prototype-parser.td
new file mode 100644
index 00000000000000..681a607da7e115
--- /dev/null
+++ b/clang/test/TableGen/target-builtins-prototype-parser.td
@@ -0,0 +1,20 @@
+// RUN: clang-tblgen -I %p/../../../clang/include/ %s --gen-clang-builtins | FileCheck %s
+// RUN: not clang-tblgen -I %p/../../../clang/include/ %s --gen-clang-builtins -DERROR_EXPECTED_LANES 2>&1 | FileCheck %s --check-prefix=ERROR_EXPECTED_LANES
+
+include "clang/Basic/BuiltinsBase.td"
+
+def : Builtin {
+ let Prototype = "ext_vector_type_8_int(double, ext_vector_type_4_bool)";
+ let Spellings = ["__builtin_test_use_clang_extended_vectors"];
+}
+
+// CHECK: BUILTIN(__builtin_test_use_clang_extended_vectors, "E8idE4b", "")
+
+#ifdef ERROR_EXPECTED_LANES
+def : Builtin {
+// ERROR_EXPECTED_LANES: :[[# @LINE + 1]]:7: error: Expected number of lanes
+ let Prototype = "ext_vector_type__int(double, ext_vector_type_4_bool)";
+ let Spellings = ["__builtin_test_use_clang_extended_vectors"];
+}
+#endif
+
diff --git a/clang/utils/TableGen/ClangBuiltinsEmitter.cpp b/clang/utils/TableGen/ClangBuiltinsEmitter.cpp
index 48f55b8af97e4e..774f703390a05e 100644
--- a/clang/utils/TableGen/ClangBuiltinsEmitter.cpp
+++ b/clang/utils/TableGen/ClangBuiltinsEmitter.cpp
@@ -85,6 +85,16 @@ class PrototypeParser {
if (Substitution.empty())
PrintFatalError(Loc, "Not a template");
ParseType(Substitution);
+ } else if (T.consume_front("ext_vector_type_")) {
+ // Clang extended vector types are mangled as follows:
+ //
+ // ext_vector_type_<lanes>_<scalar type>
+ unsigned long long Lanes;
+ if (llvm::consumeUnsignedInteger(T, 10, Lanes))
+ PrintFatalError(Loc, "Expected number of lanes ");
+ Type += "E" + std::to_string(Lanes);
+ T.consume_front("_");
+ ParseType(T);
} else {
auto ReturnTypeVal = StringSwitch<std::string>(T)
.Case("__builtin_va_list_ref", "A")
>From e7ac017c9092a99828401d2209061b02570c7dbb Mon Sep 17 00:00:00 2001
From: Francesco Petrogalli <francesco.petrogalli at apple.com>
Date: Fri, 1 Mar 2024 16:41:04 +0100
Subject: [PATCH 3/3] Move the check just before the prototype. NFC.
---
clang/test/TableGen/target-builtins-prototype-parser.td | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/clang/test/TableGen/target-builtins-prototype-parser.td b/clang/test/TableGen/target-builtins-prototype-parser.td
index 681a607da7e115..97de30d91a9491 100644
--- a/clang/test/TableGen/target-builtins-prototype-parser.td
+++ b/clang/test/TableGen/target-builtins-prototype-parser.td
@@ -4,11 +4,11 @@
include "clang/Basic/BuiltinsBase.td"
def : Builtin {
+// CHECK: BUILTIN(__builtin_test_use_clang_extended_vectors, "E8idE4b", "")
let Prototype = "ext_vector_type_8_int(double, ext_vector_type_4_bool)";
let Spellings = ["__builtin_test_use_clang_extended_vectors"];
}
-// CHECK: BUILTIN(__builtin_test_use_clang_extended_vectors, "E8idE4b", "")
#ifdef ERROR_EXPECTED_LANES
def : Builtin {
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