For a definition (of most linkage types), dso_local is set for ELF -fno-pic/-fpie
and COFF, but not for Mach-O. This nuance causes unneeded binary format differences.
This patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `
if there is an explicit linkage.
* Clang will set dso_local for Mach-O, which is currently implied by TargetMachine.cpp. This will make COFF/Mach-O and executable ELF similar.
* Eventually I hope we can make dso_local the textual LLVM IR default (write explicit "dso_preemptable" when applicable) and -fpic ELF will be similar to everything else. This patch helps move toward that goal.
After a first attempt to fix the test-suite failures, my first recommit
caused the same failures again. I had updated CMakeList.txt files of
tests that needed -fcommon, but it turns out that there are also
Makefiles which are used by some bots, so I've updated these Makefiles
now too.
See the original commit message for more details on this change:
0a9fc9233e
This includes fixes for:
- test-suite: some benchmarks need to be compiled with -fcommon, see D75557.
- compiler-rt: one test needed -fcommon, and another a change, see D75520.
This reverts commit 0a9fc9233e.
Going to look at the asan failures.
I find the failures in the test suite weird, because they look
like compile time test and I don't understand how that can be
failing, but will have a brief look at that too.
This makes -fno-common the default for all targets because this has performance
and code-size benefits and is more language conforming for C code.
Additionally, GCC10 also defaults to -fno-common and so we get consistent
behaviour with GCC.
With this change, C code that uses tentative definitions as definitions of a
variable in multiple translation units will trigger multiple-definition linker
errors. Generally, this occurs when the use of the extern keyword is neglected
in the declaration of a variable in a header file. In some cases, no specific
translation unit provides a definition of the variable. The previous behavior
can be restored by specifying -fcommon.
As GCC has switched already, we benefit from applications already being ported
and existing documentation how to do this. For example:
- https://gcc.gnu.org/gcc-10/porting_to.html
- https://wiki.gentoo.org/wiki/Gcc_10_porting_notes/fno_common
Differential revision: https://reviews.llvm.org/D75056
The previous change was insufficient to mark the content as read-write as the
structure itself was marked constant. Adjust this and add tests to ensure that
the section is marked appropriately as being read-write.
llvm-svn: 277200
Per review feedback the name was wrong and it can be used outside
Objective-C.
Unfortunately, making the internal struct visible broke some ASTMatchers
tests that assumed that the first record decl would be from user code,
rather than a builtin type. I'm worried that this will also affect
users' code. So this patch adds a typedef to wrap the internal struct
and only makes the typedef visible to namelookup. This is sufficient to
allow the ASTReader to merge the decls we need without making the struct
itself visible.
rdar://problem/24425801
llvm-svn: 259734
Original message:
Make CF constant string decl visible to name lookup to fix module errors
The return type of the __builtin___*StringMakeConstantString functions
is a pointer to a struct, so we need that struct to be visible to name
lookup so that we will correctly merge multiple declarations of that
type if they come from different modules.
Incidentally, to make this visible to name lookup we need to rename the
type to __NSConstantString, since the real NSConstantString is an
Objective-C interface type. This shouldn't affect anyone outside the
compiler since users of the constant string builtins cast the result
immediately to CFStringRef.
Since this struct type is otherwise implicitly created by the AST
context and cannot access namelookup, we make this a predefined type
and initialize it in Sema.
Note: this issue of builtins that refer to types not visible to name
lookup technically also affects other builtins (e.g. objc_msgSendSuper),
but in all other cases the builtin is a library builtin and the issue
goes away if you include the library that defines the types it uses,
unlike for these constant string builtins.
rdar://problem/24425801
llvm-svn: 259721
The return type of the __builtin___*StringMakeConstantString functions
is a pointer to a struct, so we need that struct to be visible to name
lookup so that we will correctly merge multiple declarations of that
type if they come from different modules.
Incidentally, to make this visible to name lookup we need to rename the
type to __NSConstantString, since the real NSConstantString is an
Objective-C interface type. This shouldn't affect anyone outside the
compiler since users of the constant string builtins cast the result
immediately to CFStringRef.
Since this struct type is otherwise implicitly created by the AST
context and cannot access namelookup, we make this a predefined type
and initialize it in Sema.
Note: this issue of builtins that refer to types not visible to name
lookup technically also affects other builtins (e.g. objc_msgSendSuper),
but in all other cases the builtin is a library builtin and the issue
goes away if you include the library that defines the types it uses,
unlike for these constant string builtins.
rdar://problem/24425801
llvm-svn: 259624
for caching couple of global symbols used
for generation of CF/NS string meta-data
so they are not released prematuely in certain
corner cases. // rdar:// 13598026.
Reviewed by John M.
llvm-svn: 179599
Fangrui Song