- Remove calls to pass initialization from pass constructors.
- https://github.com/llvm/llvm-project/issues/111767

In function handleMFLOSlot, we may get a variable LastInstInFunction
with a value of true from function getNextMachineInstr and IInSlot may
be null which would trigger an assert.
So we need to skip this case.

Fix #118223.

Identified with misc-include-cleaner.

Fix issue1: In mips1-4, require a minimum of 2 instructions between a
mflo/mfhi and the next mul/dmult/div/ddiv/divu/ddivu instruction.
Fix issue2: In mips1-4, should not put mflo into the delay slot for the
return.

Fix https://github.com/llvm/llvm-project/issues/81291

Differential Revision: https://reviews.llvm.org/D125391

The microMIPS instruction set is compatible with the MIPS instruction
set at the assembly level but not in terms of encodings. `nop` in
microMIPS is a special case as it has the same encoding as `nop` for
MIPS.

Fix this error by reducing the usage of NOP in the MIPS backend such
that only that ISA correct variants are produced.

Differential Revision: https://reviews.llvm.org/D124716

LLVM so far has only supported the MIPS-II and above architectures. MIPS-II is pretty close to MIPS-I, the major difference
being that "load" instructions always take one extra instruction slot to propogate to registers. This patch adds support for
MIPS-I by adding hazard handling for load delay slots, alongside MIPSR6 forbidden slots and FPU slots, inserting a NOP
instruction between a load and any instruction immediately following that reads the load's destination register. I also
included a simple regression test. Since no existing tests target MIPS-I, those all still pass.

Issue ref: https://github.com/simias/psx-sdk-rs/issues/1

I also tested by building a simple demo app with Clang and running it in an emulator.

Patch by: @impiaaa

Differential Revision: https://reviews.llvm.org/D122427