llvm-mirror/tools/gold/Makefile
Rafael Espindola 77b37756aa Rewrite the gold plugin to fix pr19901.
There is a fundamental difference between how the gold API and lib/LTO view
the LTO process.

The gold API talks about a particular symbol in a particular file. The lib/LTO
API talks about a symbol in the merged module.

The merged module is then defined in terms of the IR semantics. In particular,
a linkonce_odr GV is only copied if it is used, since it is valid to drop
unused linkonce_odr GVs.

In the testcase in pr19901 both properties collide. What happens is that gold
asks us to keep a particular linkonce_odr symbol, but the IR linker doesn't
copy it to the merged module and we never have a chance to ask lib/LTO to keep
it.

This patch fixes it by having a more direct implementation of the gold API. If
it asks us to keep a symbol, we change the linkage so it is not linkonce. If it
says we can drop a symbol, we do so. All of this before we even send the module
to lib/Linker.

Since now we don't have to produce LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN,
during symbol resolution we can use a temporary LLVMContext and do lazy
module loading. This allows us to keep the minimum possible amount of
allocated memory around. This should also allow as much parallelism as
we want, since there is no shared context.

llvm-svn: 216215
2014-08-21 20:28:55 +00:00

32 lines
1.0 KiB
Makefile

#===- tools/gold/Makefile ----------------------------------*- Makefile -*-===##
#
# The LLVM Compiler Infrastructure
#
# This file is distributed under the University of Illinois Open Source
# License. See LICENSE.TXT for details.
#
##===----------------------------------------------------------------------===##
LEVEL := ../..
LIBRARYNAME := LLVMgold
LINK_LIBS_IN_SHARED := 1
SHARED_LIBRARY := 1
LOADABLE_MODULE := 1
EXPORTED_SYMBOL_FILE = $(PROJ_SRC_DIR)/gold.exports
# Include this here so we can get the configuration of the targets
# that have been configured for construction. We have to do this
# early so we can set up LINK_COMPONENTS before including Makefile.rules
include $(LEVEL)/Makefile.config
LINK_COMPONENTS := $(TARGETS_TO_BUILD) Linker BitWriter IPO
# Because off_t is used in the public API, the largefile parts are required for
# ABI compatibility.
CXXFLAGS += -I$(BINUTILS_INCDIR) -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64
LDFLAGS += -L$(SharedLibDir)/$(SharedPrefix)
include $(LEVEL)/Makefile.common