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.
The frontend option -fno-optimize-sibling-calls resolves to -cc1's
-mdisable-tail-calls, which is passed to the TargetMachine in the
backend. PassManagerBuilder was adding the -tailcallelim pass anyway.
Use a new DisableTailCalls option in PassManagerBuilder to disable tail
calls harder.
Requires the matching commit in LLVM that adds DisableTailCalls.
<rdar://problem/16050591>
llvm-svn: 206543
Fangrui Song