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[llvm-mca][docs] Define IPC where it is first mentioned. NFC. 

Expand the abbreviation where it is first used, and use IPC elsewhere.

llvm-svn: 337739
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Matt Davis 2018-07-23 21:10:50 +00:00
parent c764e9a87e
commit 07dee81a68
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14
llvm/docs/CommandGuide/llvm-mca.rst
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@ -21,9 +21,9 @@ The main goal of this tool is not just to predict the performance of the code
when run on the target, but also help with diagnosing potential performance
issues.
Given an assembly code sequence, llvm-mca estimates the IPC, as well as
hardware resource pressure. The analysis and reporting style were inspired by
the IACA tool from Intel.
Given an assembly code sequence, llvm-mca estimates the Instructions Per Cycle
(IPC), as well as hardware resource pressure. The analysis and reporting style
were inspired by the IACA tool from Intel.
:program:`llvm-mca` allows the usage of special code comments to mark regions of
the assembly code to be analyzed. A comment starting with substring
@ -287,10 +287,10 @@ for a total of 900 dynamically executed instructions.
The report is structured in three main sections. The first section collects a
few performance numbers; the goal of this section is to give a very quick
overview of the performance throughput. In this example, the two important
performance indicators are the predicted total number of cycles, and the
Instructions Per Cycle (IPC). IPC is probably the most important throughput
indicator. A big delta between the Dispatch Width and the computed IPC is an
indicator of potential performance issues.
performance indicators are the predicted total number of cycles, and the IPC.
IPC is probably the most important throughput indicator. A big delta between
the Dispatch Width and the computed IPC is an indicator of potential
performance issues.
The second section of the report shows the latency and reciprocal
throughput of every instruction in the sequence. That section also reports