On Sun, Sep 7, 2008 at 1:58 PM, Richard Sandiford <[EMAIL PROTECTED]> wrote: >> I agree. So your plan would be to change rs6000 to an unspec, and drop >> the problematic hunk in simplify-rtx.c? That would be okay with me, but >> it's not a small change for rs6000. > > Yeah, this is very much my preferred option. > > FWIW, here's a proof-of-concept patch for GNU/Linux and AIX. > It knowingly breaks Darwin, so it can't be applied as-is. > But if the idea seems OK to David, I'll volunteer to do the > Darwin stuff too (including x86 if necessary). > > I compared the gcc.c-torture, gcc.dg and g++.dg output for the > following options: > > -O2 > -O2 -fpic > -O2 -fPIC > -O2 -mminimal-toc > > on the following targets: > > powerpc-linux-gnu > powerpc64-linux-gnu > powerpc-aix4.3 > > and there were no differences.
I do not object in principle to converting the TOC addressing to use UNSPEC. We need to ensure that this produces the same assembly code, not just lack of testsuite failures. I still think that this is ignoring the issue of simplify-rtx.c versus commutative_operand_precedence. Even if rs6000 does not rely on this idiom, simplify-rtx.c is re-grouping operands it should not change. David
