[llvm-bugs] [Bug 28821] New: Stack coloring fails to re-use stack that the inliner's alloca merging can recover

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=28821

            Bug ID: 28821
           Summary: Stack coloring fails to re-use stack that the
                    inliner's alloca merging can recover
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Common Code Generator Code
          Assignee: unassignedbugs at nondot.org
          Reporter: chandlerc at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

If I turn off the Inliner's alloca merging (flag to be committed as
-disable-inlined-alloca-merging) I've found at least one function which
regresses stack size by a surprisingly large ratio (almost 3x) despite having
*identical instructions* before and after.

My only conclusion is that the allocas could have shared space but the stack
coloring algorithm failed to recognize this for some reason.

The function is "NArchive::N7z::GetStringForSizeValue(unsigned int)" in
7zHandler.cpp in the test-suite.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20160803/b68013df/attachment.html>