The logic for marking runtime libcalls unavailable currently duplicates
essentially the same logic for some random subset of targets, where
someone reported an issue and then someone went and fixed the issue for
that specific target only. However, the availability for most of these
is completely target independent. In particular:
* MULO_I128 is never available in libgcc
* Various I128 libcalls are not available for 32-bit targets in libgcc
* powi is never available in MSVCRT
Unify the logic for these, so we don't miss any targets. This fixes
https://github.com/llvm/llvm-project/issues/16778 on AArch64, which is
one of the targets that was previously missed in this logic.
This change is part of this proposal:
https://discourse.llvm.org/t/rfc-all-the-math-intrinsics/78294
Based on example PR #96222 and fix PR #101268, with some differences due
to 2-arg intrinsic and intermediate refactor (RuntimeLibCalls.cpp).
- Add llvm.experimental.constrained.atan2 - Intrinsics.td,
ConstrainedOps.def, LangRef.rst
- Add to ISDOpcodes.h and TargetSelectionDAG.td, connect to intrinsic in
BasicTTIImpl.h, and LibFunc_ in SelectionDAGBuilder.cpp
- Update LegalizeDAG.cpp, LegalizeFloatTypes.cpp, LegalizeVectorOps.cpp,
and LegalizeVectorTypes.cpp
- Update isKnownNeverNaN in SelectionDAG.cpp
- Update SelectionDAGDumper.cpp
- Update libcalls - RuntimeLibcalls.def, RuntimeLibcalls.cpp
- TargetLoweringBase.cpp - Expand for vectors, promote f16
- X86ISelLowering.cpp - Expand f80, promote f32 to f64 for MSVC
Part 4 for Implement the atan2 HLSL Function #70096.
This reverts commit 740161a9b98c9920dedf1852b5f1c94d0a683af5.
I moved the `ISD` dependencies into the CodeGen portion of the handling,
it's a little awkward but it's the easiest solution I can think of for
now.
Summary:
The LTO pass and LLD linker have logic in them that forces extraction
and prevent internalization of needed runtime calls. However, these
currently take all RTLibcalls into account, even if the target does not
support them. The target opts-out of a libcall if it sets its name to
nullptr. This patch pulls this logic out into a class in the header so
that LTO / lld can use it to determine if a symbol actually needs to be
kept.
This is important for targets like AMDGPU that want to be able to use
`lld` to perform the final link step, but does not want the overhead of
uncalled functions. (This adds like a second to the link time trivially)
