[llvm-bugs] [Bug 39980] New: [X86] Use scheduler models to remove inputs from dependency breaking instructions

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39980

            Bug ID: 39980
           Summary: [X86] Use scheduler models to remove inputs from
                    dependency breaking instructions
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: craig.topper at gmail.com
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, spatel+llvm at rotateright.com

After r348959, the X86 backend creates more SBB instructions with a dependency
breaking MOV32r0 pseudo in front of it. On some AMD CPUs, SBB with the same
register is recognized as a dependency breaking instruction on its own. We
should remove the MOV32r0 dependency for those CPUs.

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