When a PHI use is <undef>, don't emit a copy in the predecessor block,
but insert an IMPLICIT_DEF instruction instead. This ensures that
virtual register uses are always jointly dominated by defs, even if some
of them are IMPLICIT_DEF.
llvm-svn: 159121
When the source register to a 2-addr instruction is undefined, there is
no need to attempt any transformations - simply replace the source
register with the destination register.
This also comes up when lowering IMPLICIT_DEF instructions - make sure
the <undef> flag is moved to the new partial register def operand:
%vreg8<def> = INSERT_SUBREG %vreg9<undef>, %vreg0<kill>, sub_16bit
rewrite undef:
%vreg8<def> = INSERT_SUBREG %vreg8<undef>, %vreg0<kill>, sub_16bit
convert to:
%vreg8:sub_16bit<def,read-undef> = COPY %vreg0<kill>
llvm-svn: 159120
The function live-out registers must be live at all function returns,
and %RCX is only used by eh.return. When a function also has a normal
return, only %RAX holds a return value.
This fixes PR13188.
llvm-svn: 159116
This adds support for the tls_model attribute. This allows the user to
choose a TLS model that is better than what LLVM would select by
default. For example, a variable might be declared as:
__thread int x __attribute__((tls_model("initial-exec")));
if it will not be used in a shared library that is dlopen'ed.
This depends on LLVM r159077.
llvm-svn: 159078
This allows the user/front-end to specify a model that is better
than what LLVM would choose by default. For example, a variable
might be declared as
@x = thread_local(initialexec) global i32 42
if it will not be used in a shared library that is dlopen'ed.
If the specified model isn't supported by the target, or if LLVM can
make a better choice, a different model may be used.
llvm-svn: 159077
attributes in more places where we didn't and catching a lot more issues.
This implements nearly every aspect of C++11 attribute parsing, except for:
- Attributes are permitted on explicit instantiations inside the declarator
(but not preceding the decl-spec)
- Attributes are permitted on friend declarations of functions.
- Multiple instances of the same attribute in an attribute-list (e.g.
[[noreturn, noreturn]], not [[noreturn]] [[noreturn]] which is conforming)
are allowed.
The first two are marked as expected-FIXME in the test file and the latter
is probably a defect and is currently untested.
Thanks to Richard Smith for providing the lion's share of the testcases.
llvm-svn: 159072
It's simple: Don't treat <undef> operands as uses, and don't assume a
virtual register has a defining instruction unless a real use has been
seen.
llvm-svn: 159061
Heavily based on a patch from
Aaron Wishnick <aaron.s.wishnick@gmail.com>.
I'll clean up the duplicated function in CodeGen as
a follow-up, later today or tomorrow.
llvm-svn: 159060
Jakob Stoklund Olesen