http://llvm.org/bugs/show_bug.cgi?id=2874
Summary: missed optimization opportunity: imull -> shl+add
Product: libraries
Version: trunk
Platform: PC
OS/Version: Linux
Status: NEW
Severity: enhancement
Priority: P2
Component: Backend: X86
AssignedTo: [EMAIL PROTECTED]
ReportedBy: [EMAIL PROTECTED]
CC: [email protected]
LLVM will optimize (x << 8) + x into x*257, but on some CPUs the imull is
actually slower than the shift and add. The backend should take a moment to
unfurl those multiplies when possible.
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