| Message ID | 20130906062029.kleaivsw00ggow8c-nzlynne@webmail.spamcop.net |
|---|---|
| State | New |
| Headers | show |
On Fri, Sep 6, 2013 at 12:20 PM, Joern Rennecke wrote: > We found that > > std::basic_string<char, std::char_traits<char>, std::allocator<char> > ::copy(char*, unsigned long, unsigned long) const > > got miscompiled for ARC because reorg thought that all call-clobbered > registers were dead after a conditional call. Hmm, interesting to have a target with both predication and delay slots... > I can't reproduce the test case with current trunk + ARC port, but I reckon > this is just due to the fickleness of the register allocator. Chances are, > every other version, some other obscure function is miscompiled without > this patch. > > bootstrapped on i686-pc-linux-gnu. That's not a very good test, i686 doesn't use this code ;-) > OK to apply? Yes, the patch is OK. However, I wouldn't be surprised if using COND_EXECs together with delay slots has more hidden problems. Browsing through resource.c, the "if (jump_insn)" block at lines 1095:1119 jumps out as another place you should probably look into. Ciao! Steven
diff --git a/gcc/resource.c b/gcc/resource.c Index: resource.c =================================================================== --- resource.c (revision 202295) +++ resource.c (working copy) @@ -994,11 +994,18 @@ mark_target_live_regs (rtx insns, rtx ta if (CALL_P (real_insn)) { - /* CALL clobbers all call-used regs that aren't fixed except - sp, ap, and fp. Do this before setting the result of the - call live. */ - AND_COMPL_HARD_REG_SET (current_live_regs, - regs_invalidated_by_call); + /* Values in call-clobbered registers survive a COND_EXEC CALL + if that is not executed; this matters for resoure use because + they may be used by a complementarily (or more strictly) + predicated instruction, or if the CALL is NORETURN. */ + if (GET_CODE (PATTERN (real_insn)) != COND_EXEC) + { + /* CALL clobbers all call-used regs that aren't fixed except + sp, ap, and fp. Do this before setting the result of the + call live. */ + AND_COMPL_HARD_REG_SET (current_live_regs, + regs_invalidated_by_call); + } /* A CALL_INSN sets any global register live, since it may have been modified by the call. */