Silence spurious -Wnontrivial-memcall warnings in C mode #137429
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clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.
For example:
```
struct S {
int * __ptrauth(1, 1, 100) p;
} s;
memset(&s, 0, sizeof(struct S));
```
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870
|
@llvm/pr-subscribers-clang Author: Akira Hatanaka (ahatanak) Changesclang currently issues a warning when memset is used on a struct that contains an address-discriminated pointer field, even though this is entirely valid behavior. For example: Only allow the warning to be emitted in C++ mode to silence the warning. rdar://142495870 Full diff: https://github.com/llvm/llvm-project/pull/137429.diff 2 Files Affected:
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 9c9372d9ee2b0..ee3b55c83699e 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -9724,9 +9724,9 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
// completed later. GCC does not diagnose such code, but we may want to
// consider diagnosing it in the future, perhaps under a different, but
// related, diagnostic group.
- bool MayBeTriviallyCopyableCXXRecord =
- RT->isIncompleteType() ||
- RT->desugar().isTriviallyCopyableType(Context);
+ bool NonTriviallyCopyableCXXRecord =
+ getLangOpts().CPlusPlus && !RT->isIncompleteType() &&
+ !RT->desugar().isTriviallyCopyableType(Context);
if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) &&
RT->getDecl()->isNonTrivialToPrimitiveDefaultInitialize()) {
@@ -9735,7 +9735,7 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
<< ArgIdx << FnName << PointeeTy << 0);
SearchNonTrivialToInitializeField::diag(PointeeTy, Dest, *this);
} else if ((BId == Builtin::BImemset || BId == Builtin::BIbzero) &&
- !MayBeTriviallyCopyableCXXRecord && ArgIdx == 0) {
+ NonTriviallyCopyableCXXRecord && ArgIdx == 0) {
// FIXME: Limiting this warning to dest argument until we decide
// whether it's valid for source argument too.
DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
@@ -9748,7 +9748,7 @@ void Sema::CheckMemaccessArguments(const CallExpr *Call,
<< ArgIdx << FnName << PointeeTy << 1);
SearchNonTrivialToCopyField::diag(PointeeTy, Dest, *this);
} else if ((BId == Builtin::BImemcpy || BId == Builtin::BImemmove) &&
- !MayBeTriviallyCopyableCXXRecord && ArgIdx == 0) {
+ NonTriviallyCopyableCXXRecord && ArgIdx == 0) {
// FIXME: Limiting this warning to dest argument until we decide
// whether it's valid for source argument too.
DiagRuntimeBehavior(Dest->getExprLoc(), Dest,
diff --git a/clang/test/Sema/warn-nontrivial-struct-memaccess-ptrauth.c b/clang/test/Sema/warn-nontrivial-struct-memaccess-ptrauth.c
new file mode 100644
index 0000000000000..d9cd712330c1b
--- /dev/null
+++ b/clang/test/Sema/warn-nontrivial-struct-memaccess-ptrauth.c
@@ -0,0 +1,42 @@
+// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -verify %s
+
+void *memset(void *, int, __SIZE_TYPE__);
+void bzero(void *, __SIZE_TYPE__);
+void *memcpy(void *, const void *, __SIZE_TYPE__);
+void *memmove(void *, const void *, __SIZE_TYPE__);
+
+#define AQ __ptrauth(1,1,50)
+#define IQ __ptrauth(1,0,50)
+
+struct PtrAuthTrivial {
+ int f0;
+ int * IQ f1;
+};
+
+struct PtrAuthNonTrivial0 {
+ int f0;
+ int * AQ f1; // expected-note 2 {{non-trivial to copy}}
+ int f2;
+};
+
+struct PtrAuthNonTrivial1 {
+ int * AQ f0; // expected-note 2 {{non-trivial to copy}}
+ int f1;
+ struct PtrAuthNonTrivial0 f2;
+};
+
+void testPtrAuthTrivial(struct PtrAuthTrivial *d, struct PtrAuthTrivial *s) {
+ memset(d, 0, sizeof(struct PtrAuthTrivial));
+ bzero(d, sizeof(struct PtrAuthTrivial));
+ memcpy(d, s, sizeof(struct PtrAuthTrivial));
+ memmove(d, s, sizeof(struct PtrAuthTrivial));
+}
+
+void testPtrAuthNonTrivial1(struct PtrAuthNonTrivial1 *d,
+ struct PtrAuthNonTrivial1 *s) {
+ memset(d, 0, sizeof(struct PtrAuthNonTrivial1));
+ bzero(d, sizeof(struct PtrAuthNonTrivial1));
+ memcpy(d, s, sizeof(struct PtrAuthNonTrivial1)); // expected-warning {{that is not trivial to primitive-copy}} expected-note {{explicitly cast the pointer to silence}}
+ memmove(d, s, sizeof(struct PtrAuthNonTrivial1)); // expected-warning {{that is not trivial to primitive-copy}} expected-note {{explicitly cast the pointer to silence}}
+}
|
ojhunt
reviewed
Apr 26, 2025
| RT->desugar().isTriviallyCopyableType(Context); | ||
| bool NonTriviallyCopyableCXXRecord = | ||
| getLangOpts().CPlusPlus && !RT->isIncompleteType() && | ||
| !RT->desugar().isTriviallyCopyableType(Context); |
There was a problem hiding this comment.
I would like to have isTriviallyCopyableType do any required desugaring or canonicalization rather than requiring every call site do this work, it's a constant hazard.
There was a problem hiding this comment.
Do we have to desugar the type before calling isTriviallyCopyableType? It doesn't look like other call sites are doing so.
Why is the call to desugar` needed here?
ojhunt
reviewed
Apr 26, 2025
ojhunt
reviewed
Apr 26, 2025
shafik
reviewed
Apr 26, 2025
The |
ojhunt
approved these changes
Apr 29, 2025
| // RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -x c++ -verify=cxx,expected %s | ||
| // RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -fsyntax-only -x c++ -verify=cxx,expected %s | ||
|
|
||
| #if defined __cplusplus |
There was a problem hiding this comment.
ahahah, I was literally thinking "add a -D argument to say it's C++" because I'm a muppet and forgot the builtin macro :D
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/59/builds/16905 Here is the relevant piece of the build log for the reference |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/18/builds/15265 Here is the relevant piece of the build log for the reference |
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.
For example:
```
struct S {
int * __ptrauth(1, 1, 100) p;
} s;
memset(&s, 0, sizeof(struct S));
```
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.
For example:
```
struct S {
int * __ptrauth(1, 1, 100) p;
} s;
memset(&s, 0, sizeof(struct S));
```
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870
IanWood1
pushed a commit
to IanWood1/llvm-project
that referenced
this pull request
May 6, 2025
clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.
For example:
```
struct S {
int * __ptrauth(1, 1, 100) p;
} s;
memset(&s, 0, sizeof(struct S));
```
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870
GeorgeARM
pushed a commit
to GeorgeARM/llvm-project
that referenced
this pull request
May 7, 2025
clang currently issues a warning when memset is used on a struct that
contains an address-discriminated pointer field, even though this is
entirely valid behavior.
For example:
```
struct S {
int * __ptrauth(1, 1, 100) p;
} s;
memset(&s, 0, sizeof(struct S));
```
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870
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clang currently issues a warning when memset is used on a struct that contains an address-discriminated pointer field, even though this is entirely valid behavior.
For example:
Only allow the warning to be emitted in C++ mode to silence the warning.
rdar://142495870