I tested the test case with "r13" which is another callee saved register, I think it's ok to replace.
Thanks > -----Original Message----- > From: Ye Joey [mailto:joey.ye...@gmail.com] > Sent: Friday, December 23, 2011 11:25 AM > To: Bin Cheng > Cc: gcc-patches@gcc.gnu.org; richard.guent...@gmail.com > Subject: Re: [PATCH RFA] tree-optimization/PR43491, Unnecessary temporary for > global register variable > > Writing to rbp will damage stack frame. Though it is a compile only > case, better not to write rbp. > > OK to s/rbp/r13 when commit it? > > - Joey > > On Thu, Dec 22, 2011 at 9:59 AM, Bin Cheng <bin.ch...@arm.com> wrote: > > Hi, > > > > This patch fixes the bug PR43491, which exists at least on > > arm-none-eabi/mips-elf > > targets. > > > > The cause is ssa-pre eliminates global register variable when it is the RHS > > of > > single assign statment, while following passes do not handle the > > const/register > > attributes of the variable. > > > > This patch skips the elimination of global register variable when it is the > > RHS > > of a single assignment in SSA-PRE pass. > > > > By doing this, > > > > 0) gcc won't generate the redundant move instruction as reported in the bug. > > 1) normal redundancy elimination on global registers will not be hurt, > > since sccvn and pre has already detected the true elimination chances > > and they will be eliminated afterward in function eliminate. > > 2) the inserted statements(including PHIs) for global register variables > > will not be marked as NECESSARY in function eliminate and will be > > deleted in remove_dead_inserted_code. So no redundant insertions will be > > generated in PRE pass. > > > > Some discussion can be found at: > > http://gcc.gnu.org/ml/gcc/2011-12/msg00000.html > > > > The patch is tested on x86 and arm-none-eabi, no failure introduced. > > > > Is it OK? > > > > Thanks > > > > gcc/ChangeLog: > > 2011-12-21 Bin Cheng <bin.ch...@arm.com> > > Richard Guenther <rguent...@suse.de> > > > > PR tree-optimization/43491 > > * tree-ssa-pre.c (eliminate): Don't replace global register variable > > when > > it is the RHS of a single assign. > > > > gcc/testsuite/ChangeLog: > > 2011-12-21 Bin Cheng <bin.ch...@arm.com> > > > > PR tree-optimization/43491 > > * gcc.dg/tree-ssa/pr43491.c: New test.
