On May 30, 2011, Michael Matz <m...@suse.de> wrote: > Hi, > On Mon, 30 May 2011, Alexandre Oliva wrote:
>> > 3. expand dominators before dominated blocks, so that DEFs of >> > replaceable SSA names are expanded before their uses. Expand them >> > when they're encountered, but not requiring a REG as a result. >> > Save the RTL expression that results from the expansion for use in >> > debug insns and at the non-debug use. >> >> This patch addresses some of the problems in 2, avoiding expanding code >> out of order within a block, and (hopefully) ensuring that, expanding >> dominators before dominatedblocks, DEFs are expanded before USEs. > That isn't necessary. Replaceable SSA_NAMEs are defined in the same BB as > their use, and hence they're expanded strictly before their use already > right now. Hmm... You're obviously right. I must have misinterpreted some other failure, then. Thanks, this enables some simplification to two of the patches. >> There is a theoretical possibility that a USE may be expanded before a >> DEF, depending on internal details of out-of-ssa, > This can only happen with non-replaceable SSA_NAMEs and I thought you wish > to deal only with replaceable. Yup. > That said, I dislike approach 2 for the same worries you noted. And with > the above I don't see why your approach (3) isn't workable without changes > to the BB order, which should then be a really small patch. Yup. I'll give that a try. > As SSA_NAMEs are (fairly) dense it might be better to simply use an > array instead of a pointer_map for the SSA_NAME->rtx mapping. Likewise. Thanks! -- Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/ You must be the change you wish to see in the world. -- Gandhi Be Free! -- http://FSFLA.org/ FSF Latin America board member Free Software Evangelist Red Hat Brazil Compiler Engineer
