Origami404 updated this revision to Diff 483796.
Origami404 added a comment.
[clang] add -Wvla-stack-allocation and divide different VLA warning
New behaviors:
-Wvla-stack-allocation
warns on use of a VLA that involves a stack allocation
-Wvla-portability
warns on any use of a VM type, even if -Wvla-stack-allocation is
given.
-Wvla
groups together -Wvla-stack-allocation and -Wvla-portability
Fixes: https://github.com/llvm/llvm-project/issues/57098
Link: https://reviews.llvm.org/D132952
Co-authored-by: YingChi Long <m...@inclyc.cn>
Differential Revision: https://reviews.llvm.org/D137343
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D137343/new/
https://reviews.llvm.org/D137343
Files:
clang/docs/ReleaseNotes.rst
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaType.cpp
clang/test/C/drs/dr3xx.c
clang/test/Sema/cast.c
clang/test/Sema/warn-vla.c
clang/test/SemaCXX/warn-vla.cpp
Index: clang/test/SemaCXX/warn-vla.cpp
===================================================================
--- clang/test/SemaCXX/warn-vla.cpp
+++ clang/test/SemaCXX/warn-vla.cpp
@@ -1,7 +1,10 @@
// RUN: %clang_cc1 -fsyntax-only -verify -Wvla %s
void test1(int n) { // expected-note {{here}}
- int v[n]; // expected-warning {{variable length array}} expected-note {{parameter 'n'}}
+ int v[n]; /* expected-warning {{variable length array}}
+ expected-note {{parameter 'n'}}
+ expected-warning {{variable length array that may require stack allocation used}}
+ */
}
void test2(int n, int v[n]) { // expected-warning {{variable length array}} expected-note {{parameter 'n'}} expected-note {{here}}
@@ -11,7 +14,10 @@
template<typename T>
void test4(int n) { // expected-note {{here}}
- int v[n]; // expected-warning {{variable length array}} expected-note {{parameter 'n'}}
+ int v[n]; /* expected-warning {{variable length array}}
+ expected-note {{parameter 'n'}}
+ expected-warning {{variable length array that may require stack allocation used}}
+ */
}
template<typename T>
Index: clang/test/Sema/warn-vla.c
===================================================================
--- clang/test/Sema/warn-vla.c
+++ clang/test/Sema/warn-vla.c
@@ -1,12 +1,59 @@
-// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify -Wvla %s
-// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify -Wvla %s
+// RUN: %clang_cc1 -std=c89 -fsyntax-only -verify=expected,c89 -Wvla %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify=expected,c99 -Wvla %s
+// RUN: %clang_cc1 -std=c99 -fsyntax-only -verify=expected,only-stack-allocation -Wvla-stack-alloc -Wno-vla-portability %s
void test1(int n) {
- int v[n]; // expected-warning {{variable length array}}
+ int v[n]; /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c89-warning {{variable length array that may require stack allocation used}}
+ c99-warning {{variable length array used}}
+ c99-warning {{variable length array that may require stack allocation used}}
+ only-stack-allocation-warning {{variable length array that may require stack allocation used}}
+ */
}
-void test2(int n, int v[n]) { // expected-warning {{variable length array}}
+void test2(int n, int v[n]) { /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+*/
}
-void test3(int n, int v[n]); // expected-warning {{variable length array}}
+void test3(int n, int v[n]); /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+*/
+int test4_num;
+typedef int Test4[test4_num]; /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+ expected-error {{variable length array declaration not allowed at file scope}}
+*/
+
+void func() {
+ typedef int test5[test4_num]; /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+ */
+
+ int test6[test4_num]; /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c89-warning {{variable length array that may require stack allocation used}}
+ c99-warning {{variable length array used}}
+ c99-warning {{variable length array that may require stack allocation used}}
+ only-stack-allocation-warning {{variable length array that may require stack allocation used}}
+ */
+
+ // FIXME: warn twice
+ (void)sizeof(int[test4_num]); /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+ c99-warning {{variable length array used}}
+ */
+
+ int (*test7)[test4_num]; /*
+ c89-warning {{variable length arrays are a C99 feature}}
+ c99-warning {{variable length array used}}
+ */
+}
Index: clang/test/Sema/cast.c
===================================================================
--- clang/test/Sema/cast.c
+++ clang/test/Sema/cast.c
@@ -2,7 +2,8 @@
int array[(long)(char *)0]; // expected-warning {{variable length array used}} \
// expected-warning {{variable length array folded to constant array as an extension}} \
- // expected-note {{this conversion is not allowed in a constant expression}}
+ // expected-note {{this conversion is not allowed in a constant expression}} \
+ // expected-warning {{variable length array that may require stack allocation used}}
typedef struct { unsigned long bits[(((1) + (64) - 1) / (64))]; } cpumask_t;
cpumask_t x;
Index: clang/test/C/drs/dr3xx.c
===================================================================
--- clang/test/C/drs/dr3xx.c
+++ clang/test/C/drs/dr3xx.c
@@ -86,7 +86,9 @@
/* Ensure that a constant array of variable-length arrays are still
* considered a variable-length array.
*/
- vla y[3]; /* expected-warning {{variable length array}} */
+ vla y[3]; /* expected-warning {{variable length array}}
+ expected-warning {{variable length array that may require stack allocation used}}
+ */
}
/* WG14 DR313: yes
@@ -153,10 +155,14 @@
typedef int type[dr320_v]; /* c89only-warning {{variable length arrays are a C99 feature}}
c99andup-warning {{variable length array used}}
*/
- extern type bad; /* expected-error {{variable length array declaration cannot have 'extern' linkage}} */
+ extern type bad; /* expected-error {{variable length array declaration cannot have 'extern' linkage}}
+ expected-warning {{variable length array that may require stack allocation used}}
+ */
/* C99 6.7.5.2p2, second sentence. */
- static type fine; /* expected-error {{variable length array declaration cannot have 'static' storage duration}} */
+ static type fine; /* expected-error {{variable length array declaration cannot have 'static' storage duration}}
+ expected-warning {{variable length array that may require stack allocation used}}
+ */
}
/* WG14 DR321: yes
Index: clang/lib/Sema/SemaType.cpp
===================================================================
--- clang/lib/Sema/SemaType.cpp
+++ clang/lib/Sema/SemaType.cpp
@@ -2538,7 +2538,7 @@
VLADiag = diag::err_opencl_vla;
VLAIsError = true;
} else if (getLangOpts().C99) {
- VLADiag = diag::warn_vla_used;
+ VLADiag = diag::warn_vla_portability;
VLAIsError = false;
} else if (isSFINAEContext()) {
VLADiag = diag::err_vla_in_sfinae;
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -7477,6 +7477,9 @@
}
}
+ if (R->isVariableArrayType())
+ Diag(D.getIdentifierLoc(), diag::warn_vla_stack_alloc);
+
// If this variable has a VLA type and an initializer, try to
// fold to a constant-sized type. This is otherwise invalid.
if (D.hasInitializer() && R->isVariableArrayType())
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -131,8 +131,10 @@
// C99 variable-length arrays
def ext_vla : Extension<"variable length arrays are a C99 feature">,
InGroup<VLAExtension>;
-def warn_vla_used : Warning<"variable length array used">,
- InGroup<VLA>, DefaultIgnore;
+def warn_vla_portability : Warning<"variable length array used">,
+ InGroup<VLAPortability>, DefaultIgnore;
+def warn_vla_stack_alloc : Warning<"variable length array that may require stack allocation used">,
+ InGroup<VLAStackAlloc>, DefaultIgnore;
def err_vla_in_sfinae : Error<
"variable length array cannot be formed during template argument deduction">;
def err_array_star_in_function_definition : Error<
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -827,7 +827,9 @@
def VectorConversion : DiagGroup<"vector-conversion">; // clang specific
def VexingParse : DiagGroup<"vexing-parse">;
def VLAExtension : DiagGroup<"vla-extension">;
-def VLA : DiagGroup<"vla", [VLAExtension]>;
+def VLAPortability : DiagGroup<"vla-portability">;
+def VLAStackAlloc : DiagGroup<"vla-stack-alloc">;
+def VLA : DiagGroup<"vla", [VLAExtension, VLAPortability, VLAStackAlloc]>;
def VolatileRegisterVar : DiagGroup<"volatile-register-var">;
def Visibility : DiagGroup<"visibility">;
def ZeroLengthArray : DiagGroup<"zero-length-array">;
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -425,6 +425,16 @@
``#pragma clang __debug sloc_usage`` can also be used to request this report.
- Clang no longer permits the keyword 'bool' in a concept declaration as a
concepts-ts compatibility extension.
+- Added ``-Wvla-stack-allocation`` to only give warnings about VLA that need
+ stack allocation.
+
+ .. code-block:: C
+
+ void f(int n) {
+ int a[n]; // VLA that needs stack allocation
+ }
+
+ void g(int n, int a[n]) {} // VLA that don't need stack allocation
Non-comprehensive list of changes in this release
-------------------------------------------------
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