To pave the way for simple DLL generation (end goal:
druntime-ldc-shared.dll).
The dllexport storage class for functions definitions is enough; the
automatically generated import .lib seems to resolve the regular symbol
name to the actual symbol (__imp_*), so dllimport for declarations seems
superfluous.
For global variables, things are apparently different unfortunately.
And streamline implicit -singleobj with DMD, also enforcing it when
compiling a *single* module *and* specifying the -of name.
[-makedeps currently depends on -singleobj.]
This uses LLVM's TimeProfiler functionality, such that LLVM's work is traced in the same profile (optimization and machine code gen).
Functionality is meant to be identical to Clang and LLD's --ftime-trace.
I.e., *define* templated symbols in each referencing compilation unit
when using discardable linkonce_odr linkage, analogous to C++.
This makes each compilation unit self-sufficient wrt. templated symbols,
which also means increased opportunity for inlining and less need for
LTO. There should be no more undefined symbol issues caused by buggy
template culling.
The biggest advantage is that the optimizer can discard unused
linkonce_odr symbols early instead of optimizing and forwarding to the
assembler. So this is especially useful with -O to decrease compilation
times and can at least in some scenarios greatly outweigh the
(potentially very much) higher number of symbols defined by the glue
layer.
Libraries compiled with -linkonce-templates can generally not be linked
against dependent code compiled without -linkonce-templates; the other
way around works.
Incl. making sure `-cov=N ... -cov[=ctfe]` doesn't reset the required
percentage to 0.
Use a dummy *bool* option for a better help output (displaying `--cov`,
not `--cov=<value>`).
This patch gives new option which avoids the PLT and lazy binding while
making external calls.
Implementation inspired by `-fno-plt` support to Clang.
Clang's patch: https://reviews.llvm.org/D39079
This is a breaking change, conforming to new DMD semantics.
The previous semantics were inconsistent, as -{enable,disable}-asserts
and -boundscheck (as well as new -{enable,disable}-switch-errors)
weren't overridden.
