Encoding optimization:
```
mi/mi32 -> mi8
ri/ri32 -> ri8
```
if the immediate operand is 8-bit wide.
Assembler relaxation:
```
mi8 -> mi/mi32
ri8 -> ri/ri32
```
If the immediate operand is a symbol expression and it's value is
unknown.
PUSH[16|32|64]i[8|32] are not arithmetic instructions, so I renamed the
functions.
Reviewed By: Amir
Differential Revision: https://reviews.llvm.org/D151028
This caused compiler assertions, see comment on
https://reviews.llvm.org/D150107.
This also reverts the dependent follow-up change:
> [X86] Remove patterns for ADD/AND/OR/SUB/XOR/CMP with immediate 8 and optimize during MC lowering, NFCI
>
> This is follow-up of D150107.
>
> In addition, the function `X86::optimizeToFixedRegisterOrShortImmediateForm` can be
> shared with project bolt and eliminates the code in X86InstrRelaxTables.cpp.
>
> Differential Revision: https://reviews.llvm.org/D150949
This reverts commit 2ef8ae134828876ab3ebda4a81bb2df7b095d030 and
5586bc539acb26cb94e461438de01a5080513401.
This is follow-up of D150107.
In addition, the function `X86::optimizeToFixedRegisterOrShortImmediateForm` can be
shared with project bolt and eliminates the code in X86InstrRelaxTables.cpp.
Differential Revision: https://reviews.llvm.org/D150949
1. Share code `optimizeInstFromVEX3ToVEX2` with MCInstLower
2. Move the code of optimization for shift/rotate to a separate file
3. Since the function is shared, a side effect is that more encoding
optimizations are done on the Asmparser side. Considering we already
use reverse-encoding for optimization in AsmParser before this patch,
I believe the change is positive and expected.
This is a reland of D150068 with the fix D150440.
1. Share code `optimizeInstFromVEX3ToVEX2` with MCInstLower
2. Move the code of optimization for shift/rotate to a separate file
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D150068
