For a default visibility external linkage definition, dso_local is set for ELF
-fno-pic/-fpie and COFF and Mach-O. Since default clang -cc1 for ELF is similar
to -fpic ("PIC Level" is not set), this nuance causes unneeded binary format differences.
To make emitted IR similar, ELF -cc1 -fpic will default to -fno-semantic-interposition,
which sets dso_local for default visibility external linkage definitions.
To make this flip smooth and enable future (dso_local as definition default),
this patch replaces (function) `define ` with `define{{.*}} `,
(variable/constant/alias) `= ` with `={{.*}} `, or inserts appropriate `{{.*}} `.
As described here:
https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623
In order to allow Lambdas to be used with traditional Win32 APIs, they
emit a conversion function for (what Raymond Chen claims is all) a
number of the calling conventions. Through experimentation, we
discovered that the list isn't quite 'all'.
This patch implements this by taking the list of conversions that MSVC
emits (across 'all' architectures, I don't see any CCs on ARM), then
emits them if they are supported by the current target.
However, we also add 3 other options (which may be duplicates):
free-function, member-function, and operator() calling conventions. We
do this because we have an extension where we generate both free and
member for these cases so th at people specifying a calling convention
on the lambda will have the expected behavior when specifying one of
those two.
MSVC doesn't seem to permit specifying calling-convention on lambdas,
but we do, so we need to make sure those are emitted as well. We do this
so that clang-only conventions are supported if the user specifies them.
Differential Revision: https://reviews.llvm.org/D90634
As mentioned in the defect, the lambda static invoker does not follow
the calling convention of the lambda itself, which seems wrong. This
patch ensures that the calling convention of operator() is passed onto
the invoker and conversion-operator type.
This is accomplished by extracting the calling-convention determination
code out into a separate function in order to better reflect the 'thiscall'
work, as well as somewhat better support the future implementation of
https://devblogs.microsoft.com/oldnewthing/20150220-00/?p=44623
For any target (basically just win32) that has a different free and
static function calling convention, this generates BOTH alternatives.
This required some work to get the Windows mangler to work correctly for
this, as well as some tie-breaking for the unary operators.
Differential Revision: https://reviews.llvm.org/D89559
Fangrui Song