When link-time garbage collection is in use (-gc-sections), it is
often useful to mark sections that should not be eliminated.
This is accomplished by surrounding an input section's wildcard
entry with KEEP(). Patch implements that command.
Differential revision: http://reviews.llvm.org/D17242
llvm-svn: 261616
Each rule in SECTIONS commands is something like ".foo *(.baz.*)",
which instructs the linker to collect all sections whose name matches
".baz.*" from all files and put them into .foo section.
Previously, we didn't recognize the wildcard character. This patch
adds that feature.
Performance impact is a bit concerning because a linker script can
contain hundreds of SECTIONS rules, and doing pattern matching against
each rule would be too expensive. We could merge all patterns into
single DFA so that it takes O(n) to the input size. However, it is
probably too much at this moment -- we don't know whether the
performance of pattern matching matters or not. So I chose to
implement the simplest algorithm in this patch. I hope this simple
pattern matcher is sufficient.
llvm-svn: 260745
Previously, we had code for linker scripts in Writer. This patch
separates that as LinkerScript class. The class provides a few
functions to query linker scripts and is also a container of some
linker-script-specific information.
Hopefully, Writer will only implement the default behavior and let
the new class handle gotchas regarding linker scripts.
llvm-svn: 260591
George Rimar