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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [llvm-exegesis] Idealized Resource Pressure misinterprets ProcResGroups"
href="https://bugs.llvm.org/show_bug.cgi?id=37697">37697</a>
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<th>Summary</th>
<td>[llvm-exegesis] Idealized Resource Pressure misinterprets ProcResGroups
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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>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
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<th>CC</th>
<td>andrea.dibiagio@gmail.com, clement.courbet@gmail.com, gchatelet@google.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
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<pre>I've seeing cases where the Idealized Resource Pressure calculation is
idealising for use on resources that the model doesn't refer to.
These seem to be caused by having common root groups.
For instance, on btver2:
def JFPU0 : ProcResource<1>; // Vector/FPU Pipe0: VALU0/VIMUL/FPA
def JFPU1 : ProcResource<1>; // Vector/FPU Pipe1: VALU1/STC/FPM
// Fpu Pipe Scheduler
def JFPU01 : ProcResGroup<[JFPU0, JFPU1]> {
let BufferSize=18;
}
For instructions that only use JFPU0 or JFPU1, we see idealized predictions
using JFPU01 but then get applied to the other resources:
WriteProcRes:
JFPU01: 1
JFPU0: 1
Idealized Resource Pressure
JFPU0: 0.50 <--- HUH?
JFPU1: 1.50</pre>
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