[libc] fix -Wmissing-attributes in setjmp #112415
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@llvm/pr-subscribers-libc Author: Nick Desaulniers (nickdesaulniers) ChangesFixes: observed in the GCC build by manually expanding LLVM_LIBC_FUNCTION to add We probably need to revisit adding nothrow throughout our declarations, so Link: #88054 Full diff: https://github.com/llvm/llvm-project/pull/112415.diff 2 Files Affected:
diff --git a/libc/src/setjmp/setjmp_impl.h b/libc/src/setjmp/setjmp_impl.h
index 4175a7397ae187..a9f330d4722e10 100644
--- a/libc/src/setjmp/setjmp_impl.h
+++ b/libc/src/setjmp/setjmp_impl.h
@@ -16,6 +16,7 @@
namespace LIBC_NAMESPACE_DECL {
+[[gnu::nothrow]]
int setjmp(jmp_buf buf);
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/setjmp/x86_64/setjmp.cpp b/libc/src/setjmp/x86_64/setjmp.cpp
index c9ca578fb1e6db..7854132a83583c 100644
--- a/libc/src/setjmp/x86_64/setjmp.cpp
+++ b/libc/src/setjmp/x86_64/setjmp.cpp
@@ -17,8 +17,13 @@
namespace LIBC_NAMESPACE_DECL {
-[[gnu::naked]]
-LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
+LLVM_LIBC_FUNCTION_ATTR decltype(LIBC_NAMESPACE::setjmp) __setjmp_impl__ __asm__("setjmp");
+
+decltype(LIBC_NAMESPACE::setjmp) setjmp [[gnu::alias("setjmp"), gnu::nothrow]];
+
+[[gnu::naked, gnu::nothrow]]
+int __setjmp_impl__ (__jmp_buf *buf) {
+
asm(R"(
mov %%rbx, %c[rbx](%%rdi)
mov %%rbp, %c[rbp](%%rdi)
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✅ With the latest revision this PR passed the C/C++ code formatter. |
lntue
reviewed
Oct 15, 2024
|
It seems that naked functions are implicitly nothrow in GCC: https://godbolt.org/z/3Yv1ae5rv |
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Fixes:
llvm-project/libc/src/setjmp/x86_64/setjmp.cpp:21:25: error: ‘int
__llvm_libc_19_0_0_git::setjmp(__jmp_buf*)’ specifies less restrictive
attribute than its target ‘int
__llvm_libc_19_0_0_git::__setjmp_impl__(__jmp_buf*)’: ‘nothrow’
[-Werror=missing-attributes]
21 | LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
| ^~~~~~
Marking functions as 'naked' implies 'nothrow', so the function declaration
should be marked nothrow. Only do this conditionally for GCC for now, otherwise
clang with diagnose -Wmissing-exception-spec on the __ ## name ## _impl__
alias.
We probably need to revisit adding nothrow throughout our definitions, so
there is probably a better way to clean this up in the future.
Link: llvm#88054
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lntue
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Oct 15, 2024
DanielCChen
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Oct 16, 2024
Fixes:
llvm-project/libc/src/setjmp/x86_64/setjmp.cpp:21:25: error: ‘int
__llvm_libc_19_0_0_git::setjmp(__jmp_buf*)’ specifies less restrictive
attribute than its target ‘int
__llvm_libc_19_0_0_git::__setjmp_impl__(__jmp_buf*)’: ‘nothrow’
[-Werror=missing-attributes]
21 | LLVM_LIBC_FUNCTION(int, setjmp, (__jmp_buf * buf)) {
| ^~~~~~
observed in the GCC build by manually expanding LLVM_LIBC_FUNCTION to add
`gnu::nothrow` to the alias.
We probably need to revisit adding nothrow throughout our declarations, so
there is probably a better way to clean this up in the future.
Link: llvm#88054
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Fixes:
observed in the GCC build by manually expanding LLVM_LIBC_FUNCTION to add
gnu::nothrowto the alias.We probably need to revisit adding nothrow throughout our declarations, so
there is probably a better way to clean this up in the future.
Link: #88054