This is the mail archive of the mailing list for the GCC project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Fix PR 20100, PR 20115. Remove pass_maybe_create_global_var.

Andrew Pinski wrote:

On Feb 23, 2005, at 12:03 AM, Diego Novillo wrote:

We were creating .GLOBAL_VAR before comptuing aliases to avoid
the initial SSA creation to deal with too many virtual operands.
So, we do an IL scan, and if we find a lot of function calls, we
would create .GLOBAL_VAR.  A better solution is to just not
bother adding virtual operands at call sites if aliases have not
been computed.  This gives us a minor speedup in operand
scanning and SSA rewriting.

Note that pass_maybe_create_global_var was added to speed up
the compiler. See PR 15855.  I think you just slowed down this
testcase again.

No. Read my description again. We are doing *less* work without this pass:

 ...                             Before  After
 tree PTA                        0.85    0.80     -5.9%
 tree alias analysis             1.08    0.95    -12.0%
 tree SSA rewrite                2.43    2.34     -3.7%
 tree SSA other                  5.71    5.68     -0.5%
 tree operand scan               4.91    4.78     -2.6%
 dominator optimization          3.56    3.25     -8.7%

(PR 15855 is part of my collection of test cases I use to test compile time speed).


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]