[llvm-bugs] [Bug 46118] New: Large numbers of (e.g., 27) redundant vxorpd generated on loop entry
via llvm-bugs
llvm-bugs at lists.llvm.org
Thu May 28 01:53:41 PDT 2020
https://bugs.llvm.org/show_bug.cgi?id=46118
Bug ID: 46118
Summary: Large numbers of (e.g., 27) redundant vxorpd generated
on loop entry
Product: new-bugs
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: new bugs
Assignee: unassignedbugs at nondot.org
Reporter: elrodc at gmail.com
CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org
The generated code does the following:
vxorp 27 registers
checks if the loop iterates at least once. If it doesn't, jump.
vxorp those exact same 27 registers
enters loop.
The second set of 27 vxorpd is unnecessary, those registers are all already 0.
Godbolt:
https://godbolt.org/z/nsc7kc
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