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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [llvm-mca] Add the ability to mark section(s) of code for analysis"
href="https://bugs.llvm.org/show_bug.cgi?id=36875">36875</a>
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<th>Summary</th>
<td>[llvm-mca] Add the ability to mark section(s) of code for analysis
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<th>Product</th>
<td>new-bugs
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
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<th>Assignee</th>
<td>andrea.dibiagio@gmail.com
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
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<th>CC</th>
<td>atrick@apple.com, clement.courbet@gmail.com, craig.topper@gmail.com, greg.bedwell@sony.com, hfinkel@anl.gov, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
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<pre>Currently llvm-mca will analyse all the asm data in an input file, this often
means that it can be tricky to get analysis for a hot loop section of code
without all the prologue/epilogue/branches/return code getting in the way.
What would be ideal is if we had a way to mark the section(s) of code that we
actually want an analysis for - in raw asm this will require
comments/directives of some sort.
What would be even better would be is if we could provide these markers in
C++/IR code to make it easy to pipe the asm directly into llvm-mca, this would
be similar to IACA's IACA_START/IACA_END macros but without inserting any code
into the final object file.
Not sure if we might have to treat these marker as some sort of barrier so it
might affect the ordering of instructions?
I don't know the best way to handle multiple sections - outputting one section
after another obviously, I don't think we need any 'multi section' summary -
but we might need an user friendly way in the marker to distinguish between
sections (or maybe loc is enough)?.
Yet another thing that might be of use is if there is a way that we could
include this in debug/DWARF data to help with comparing static analysis vs
profiling.</pre>
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