This adds infrastructure to print and parse MIR MachineOperand comments.
The motivation for the ARM backend is to print condition code names instead of
magic constants that are difficult to read (for human beings). For example,
instead of this:
dead renamable $r2, $cpsr = tEOR killed renamable $r2, renamable $r1, 14, $noreg
t2Bcc %bb.4, 0, killed $cpsr
we now print this:
dead renamable $r2, $cpsr = tEOR killed renamable $r2, renamable $r1, 14 /* CC::always */, $noreg
t2Bcc %bb.4, 0 /* CC:eq */, killed $cpsr
This shows that MachineOperand comments are enclosed between /* and */. In this
example, the EOR instruction is not conditionally executed (i.e. it is "always
executed"), which is encoded by the 14 immediate machine operand. Thus, now
this machine operand has /* CC::always */ as a comment. The 0 on the next
conditional branch instruction represents the equal condition code, thus now
this operand has /* CC:eq */ as a comment.
As it is a comment, the MI lexer/parser completely ignores it. The benefit is
that this keeps the change in the lexer extremely minimal and no target
specific parsing needs to be done. The changes on the MIPrinter side are also
minimal, as there is only one target hooks that is used to create the machine
operand comments.
Differential Revision: https://reviews.llvm.org/D74306
This reverts commit e34801c8e6 and the followup due to multiple
problems.
I've tried to keep the tests and RDA parts where possible, as those
still seem useful.
The mve-phireg.ll test no longer really tests what it was added for,
but the original case was fairly complex. I've left the test in as a
general codegen test.
This is a recommit of D71330, but with a few things fixed and changed:
1) ReachingDefAnalysis: this was not running with optnone as it was checking
skipFunction(), which other analysis passes don't do. I guess this is a
copy-paste from a codegen pass.
2) VPTBlockPass: here I've added skipFunction(), because like most/all
optimisations, we don't want to run this with optnone.
This fixes the issues with the initial/previous commit: the VPTBlockPass was
running with optnone, but ReachingDefAnalysis wasn't, and so VPTBlockPass was
crashing querying ReachingDefAnalysis.
I've added test case mve-vpt-block-optnone.mir to check that we don't run
VPTBlock with optnone.
Differential Revision: https://reviews.llvm.org/D71470
Sjoerd Meijer