dead code.
This is important for C++ templates that essentially compute the valid
input in a way that is constant and will cause all the invalid cases to
be dead code that is deleted. Code in the wild actually does this and
GCC also accepts these kinds of patterns so it is important to support
it.
To make this work, we provide a non-error path to diagnose these issues,
and use a default-error warning instead. This keeps the relatively
strict handling but prevents nastiness like SFINAE on these errors. It
also allows us to safely use the system to diagnose this only when it
occurs at runtime (in emitted code).
Entertainingly, this required fixing the syntax in various other ways
for the x86 test because we never bothered to diagnose that the returns
were invalid.
Since debugging these compile failures was super confusing, I've also
improved the diagnostic to actually say what the value was. Most of the
checks I've made ignore this to simplify maintenance, but I've checked
it in a few places to make sure the diagnsotic is working.
Depends on D48462. Without that, we might actually crash some part of
the compiler after bypassing the error here.
Thanks to Richard, Ben Kramer, and especially Craig Topper for all the
help here.
Differential Revision: https://reviews.llvm.org/D48464
llvm-svn: 335309
This adds low-level builtins to allow access to all of the z13 vector
instructions. Note that instructions whose semantics can be described
by standard C (including clang extensions) do not get any builtins.
For each instructions whose semantics *cannot* (fully) be described, we
define a builtin named __builtin_s390_<insn> that directly maps to this
instruction. These are intended to be compatible with GCC.
For instructions that also set the condition code, the builtin will take
an extra argument of type "int *" at the end. The integer pointed to by
this argument will be set to the post-instruction CC value.
For many instructions, the low-level builtin is mapped to the corresponding
LLVM IR intrinsic. However, a number of instructions can be represented
in standard LLVM IR without requiring use of a target intrinsic.
Some instructions require immediate integer operands within a certain
range. Those are verified at the Sema level.
Based on a patch by Richard Sandiford.
llvm-svn: 236532
Chandler Carruth