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[MCA] Add flag -show-encoding to llvm-mca.
Audit Requiredcbec9af6bfb0

Authored by andreadb on Aug 9 2019, 4:26 AM.

Description

[MCA] Add flag -show-encoding to llvm-mca.

Flag -show-encoding enables the printing of instruction encodings as part of the
the instruction info view.

Example (with flags -mtriple=x86_64-- -mcpu=btver2):

Instruction Info:
[1]: #uOps
[2]: Latency
[3]: RThroughput
[4]: MayLoad
[5]: MayStore
[6]: HasSideEffects (U)
[7]: Encoding Size

[1] [2] [3] [4] [5] [6] [7] Encodings: Instructions:
1 2 1.00 4 c5 f0 59 d0 vmulps %xmm0, %xmm1, %xmm2
1 4 1.00 4 c5 eb 7c da vhaddps %xmm2, %xmm2, %xmm3
1 4 1.00 4 c5 e3 7c e3 vhaddps %xmm3, %xmm3, %xmm4

In this example, column Encoding Size is the size in bytes of the instruction
encoding. Column Encodings reports the actual instruction encodings as byte
sequences in hex (objdump style).

The computation of encodings is done by a utility class named mca::CodeEmitter.

In future, I plan to expose the CodeEmitter to the instruction builder, so that
information about instruction encoding sizes can be used by the simulator. That
would be a first step towards simulating the throughput from the decoders in the
hardware frontend.

Differential Revision: https://reviews.llvm.org/D65948

llvm-svn: 368432

Details

Auditors
grosbach
Committed
andreadbAug 9 2019, 4:26 AM
Differential Revision
D65948: [MCA] Add flag -show-encoding to llvm-mca.
Parents
rG3cdd586be28f: [AArch64] Set pref. func. align to 8 bytes on Neoverse E1 & Cortex-A65
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