[RISCV] Re-separate unaligned scalar and vector memory features in the backend. (#88954)

This is largely a revert of commit
e81796671890b59c110f8e41adc7ca26f8484d20.

As #88029 shows, there exist

[RISCV] Re-separate unaligned scalar and vector memory features in the backend. (#88954)

This is largely a revert of commit
e81796671890b59c110f8e41adc7ca26f8484d20.

As #88029 shows, there exists hardware that only supports unaligned
scalar.

I'm leaving how this gets exposed to the clang interface to a future
patch.

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[RISCV] Collapse fast unaligned access into a single feature [nfc-ish] (#73971)

When we'd originally added unaligned-scalar-mem and
unaligned-vector-mem, they were separated into two parts under th

[RISCV] Collapse fast unaligned access into a single feature [nfc-ish] (#73971)

When we'd originally added unaligned-scalar-mem and
unaligned-vector-mem, they were separated into two parts under the
theory that some processor might implement one, but not the other. At
the moment, we don't have evidence of such a processor. The C/C++ level
interface, and the clang driver command lines have settled on a single
unaligned flag which indicates both scalar and vector support unaligned.
Given that, let's remove the test matrix complexity for a set of
configurations which don't appear useful.

Given these are internal feature names, I don't think we need to provide
any forward compatibility. Anyone disagree?

Note: The immediate trigger for this patch was finding another case
where the unaligned-vector-mem wasn't being properly serialized to IR
from clang which resulted in problems reproducing assembly from clang's
-emit-llvm feature. Instead of fixing this, I decided getting rid of the
complexity was the better approach.

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[RISCV] Add memcpy lowering test coverage with and without V

[RISCV] Set Fast flag for unaligned memory accesses

The +unaligned-scalar-mem and +unaligned-vector-mem features were added in
D126085 and D149375 respectively to allow subtargets to indicate that
t

[RISCV] Set Fast flag for unaligned memory accesses

The +unaligned-scalar-mem and +unaligned-vector-mem features were added in
D126085 and D149375 respectively to allow subtargets to indicate that
they supported misaligned loads/stores with "sufficient" performance.
This is separate from whether or not the target actually supports
misaligned accesses, which could be determined from Zicclsm.

This patch enables the Fast flag under the assumption that any subtarget
that declares support for +unaligned-*-mem will want to opt into
optimisations that take advantage of misaligned scalar accesses, such as
store merging.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D150771

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[RISCV] Revise check names for unaligned memory op tests [nfc]

This has come up a few times in review; the current ones seem to be universally confusing. Even I as the original author of most of th

[RISCV] Revise check names for unaligned memory op tests [nfc]

This has come up a few times in review; the current ones seem to be universally confusing. Even I as the original author of most of these get confused. Switch to using the SLOW/FAST naming used by x86, hopefully that's a bit clearer.

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[RISCV] Use LBU for extloadi8.

The Zcb extension has c.lbu, but not c.lb. This patch makes us
prefer LBU over LB if we have a choice which will enable more
compression opportunities.

Reviewed By: a

[RISCV] Use LBU for extloadi8.

The Zcb extension has c.lbu, but not c.lb. This patch makes us
prefer LBU over LB if we have a choice which will enable more
compression opportunities.

Reviewed By: asb

Differential Revision: https://reviews.llvm.org/D146270

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Revert "[CGP] Add generic TargetLowering::shouldAlignPointerArgs() implementation"

These commits are causing a test-suite build failure on AIX. Revert for now for time to investigate.
https://lab.ll

Revert "[CGP] Add generic TargetLowering::shouldAlignPointerArgs() implementation"

These commits are causing a test-suite build failure on AIX. Revert for now for time to investigate.
https://lab.llvm.org/buildbot/#/builders/214/builds/5779/steps/9/logs/stdio

This reverts commit bd87a2449da0c82e63cebdf9c131c54a5472e3a7 and 4c72266830ffa332ebb7cf1d3bbd6c56d001fa0f.

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[CGP] Add generic TargetLowering::shouldAlignPointerArgs() implementation

This function was added for ARM targets, but aligning global/stack pointer
arguments passed to memcpy/memmove/memset can imp

[CGP] Add generic TargetLowering::shouldAlignPointerArgs() implementation

This function was added for ARM targets, but aligning global/stack pointer
arguments passed to memcpy/memmove/memset can improve code size and
performance for all targets that don't have fast unaligned accesses.
This adds a generic implementation that adjusts the alignment to pointer
size if unaligned accesses are slow.
Review D134168 suggests that this significantly improves performance on
synthetic benchmarks such as Dhrystone on RV32 as it avoids memcpy() calls.

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D134282

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[RISCV] Convert some tests to opaque pointers (NFC)

[RISCV] Teach shouldConvertConstantLoadToIntImm that constant materialization can use constant pools.

I think it only makes sense to return true here if we aren't going
to turn around and create a c

[RISCV] Teach shouldConvertConstantLoadToIntImm that constant materialization can use constant pools.

I think it only makes sense to return true here if we aren't going
to turn around and create a constant pool for the immmediate.

I left out the check for useConstantPoolForLargeInts() thinking
that even if you don't want the commpiler to create a constant pool
you might still want to avoid materializing an integer that is
already available in a global variable.

Test file was copied from AArch64/ARM and has not been commited yet.
Will post separate review for that.

Reviewed By: luismarques

Differential Revision: https://reviews.llvm.org/D129402

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[RISCV] Add test cases for inline memcpy expansion

Test file was taken directly from AArch64/ARM. I've added RUN
lines for aligned and unaligned since many of the test cases
are strings that aren't

[RISCV] Add test cases for inline memcpy expansion

Test file was taken directly from AArch64/ARM. I've added RUN
lines for aligned and unaligned since many of the test cases
are strings that aren't aligned and have an odd size.

Some of these test cases are modified by D129402.

Differential Revision: https://reviews.llvm.org/D129403

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