[LLVMbugs] [Bug 14481] New: ColdCC poorly implemented (ignored) on X86/X86_64

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=14481

             Bug #: 14481
           Summary: ColdCC poorly implemented (ignored) on X86/X86_64
           Product: new-bugs
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: willdtz at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified


Created attachment 9631
  --> http://llvm.org/bugs/attachment.cgi?id=9631
Example fix for X86/X86_64

Calls to coldcc functions unnecessarily are treated as clobbering registers in
the same manner as normal calls.  Instead, we should better model the "this
call clobbers nothing" property that makes coldcc useful.

Attached is a works-for-me(TM) patch that resolves this issue on x86_64, and
might work on X86 as well.  Ideally this could be implemented in a more
target-agnostic manner, but I'm not sure how to best approach that.  I leave
that to the good folk more familiar with the related components :).

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