[mono][jit] Partially implemented logical immediates on arm64 #93606
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jandupej
requested review from
vargaz,
lambdageek and
SamMonoRT
as code owners
lambdageek
reviewed
Oct 17, 2023
src/mono/mono/mini/mini-arm64.c
Outdated
| @@ -620,62 +625,131 @@ emit_subx_sp_imm (guint8 *code, int imm) | |||
| return code; | |||
| } | |||
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| static int | |||
| num_trailing_zeros (guint64 imm) | |||
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Can we put this in a header in mono/utils (or in minipal) so we can use it in more places
vargaz
approved these changes
Oct 17, 2023
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CI failures are not related. Merging. |
ghost
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This implements a subset of https://developer.arm.com/documentation/ddi0596/2020-12/Base-Instructions/AND--immediate---Bitwise-AND--immediate-- (incl.
ands,eor,orr). If the immediate value can be expressed as(1<<n) - 1, the new codegen is used. Although this covers only a few of the cases supported by the instruction, the instances where we are trying to mask away some of the upper bits seem prevalent (in our codebase) and are handled here.E.g. clamping the shift amount in long shifts:
becomes
EDIT: The recognized bit pattern is now expanded to
0*1+0*. A plain-ish HelloWorld build revealed almost 400 instances of this pattern.