[llvm-commits] Patch to safely restore optimization to testcase from PR3225 on x86

Eli Friedman eli.friedman at gmail.com
Tue Dec 16 21:40:28 PST 2008

A little while ago, I committed a patch for PR3225 which disables a
dangerous optimization for expanding double-width shifts (e.g. 64-bit
shifts on x86).  This significantly pessimized the code generated on
x86 for the cases which the optimization covered.

The attached performs a similar optimization in x86 platform-specific
code, which significantly improves code quality for the cases it
covers; this version is safe because SHLD/SHRD do the right thing for
shifts with a zero amount.

Any comments?

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: x.txt
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20081216/90d971ea/attachment.txt>

More information about the llvm-commits mailing list