Similar to 806761a7629df268c8aed49657aeccffa6bca449.
For IR files without a target triple, -mtriple= specifies the full
target triple while -march= merely sets the architecture part of the
default target triple, leaving a target triple which may not make sense,
e.g. amdgpu-apple-darwin.
Therefore, -march= is error-prone and not recommended for tests without
a target triple. The issue has been benign as we recognize
$unknown-apple-darwin as ELF instead of rejecting it outrightly.
This patch changes AMDGPU tests to not rely on the default
OS/environment components. Tests that need fixes are not changed:
```
LLVM :: CodeGen/AMDGPU/fabs.f64.ll
LLVM :: CodeGen/AMDGPU/fabs.ll
LLVM :: CodeGen/AMDGPU/floor.ll
LLVM :: CodeGen/AMDGPU/fneg-fabs.f64.ll
LLVM :: CodeGen/AMDGPU/fneg-fabs.ll
LLVM :: CodeGen/AMDGPU/r600-infinite-loop-bug-while-reorganizing-vector.ll
LLVM :: CodeGen/AMDGPU/schedule-if-2.ll
```
Add support for emitting GFX11.5 s_singleuse_vdst instructions. This is
a power saving feature whereby the compiler can annotate VALU
instructions whose results are known to have only a single use, so the
hardware can in some cases avoid writing the result back to VGPR RAM.
To begin with the pass is disabled by default because of one missing
feature: we need an exclusion list of opcodes that never qualify as
single-use producers and/or consumers. A future patch will implement
this and enable the pass by default.
---------
Co-authored-by: Scott Egerton <scott.egerton@amd.com>
