[LLVMbugs] [Bug 18344] New: llc doesn't optimize load from XMM well enough.
bugzilla-daemon at llvm.org
bugzilla-daemon at llvm.org
Mon Dec 30 04:37:08 PST 2013
http://llvm.org/bugs/show_bug.cgi?id=18344
Bug ID: 18344
Summary: llc doesn't optimize load from XMM well enough.
Product: tools
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: llc
Assignee: unassignedbugs at nondot.org
Reporter: ili.filippov at gmail.com
CC: llvmbugs at cs.uiuc.edu
Classification: Unclassified
Created attachment 11798
--> http://llvm.org/bugs/attachment.cgi?id=11798&action=edit
Reproducer
This issue is reproducible with LLVM trunk.
The reproducer is attached.
Command to reproduce: llc -O2 reproducer.ll
llc generates the sequence of instructions:
vmovdqa %xmm0, -24(%rsp)
movslq -24(%rsp), %rax
movslq -20(%rsp), %rcx
movslq -16(%rsp), %rdx
movslq -12(%rsp), %r8
but it seems that another sequence of instructions will be more efficient:
vpextrd $0, %xmm0, %rax
vpextrd $1, %xmm0, %rcx
vpextrd $2, %xmm0, %rdx
vpextrd $3, %xmm0, %r8
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