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 `{{.*}} `.
Some function declarations like this:
void foo();
do not have a type declaration, for that you'd use:
void foo(void);
Clang internally bitcasts the variadic function declaration to a
function pointer, but doesn't use the correct address space on AVR. This
commit fixes that.
This fix is necessary to let Clang compile compiler-rt for AVR.
Differential Revision: https://reviews.llvm.org/D78125
Ben Shi