search for: adjustcopiesbackfrom

...lt;Vreg1, hi_sub_reg, Vreg2, lo_sub_reg> ; B >> is a >> 64 bit virt reg. > > I used this approach and it worked find until I hit, what I believe is, a > bug in the register coalescer. > When the register coalescer cannot trivially coalesce a copy, say C,, it > calls AdjustCopiesBackFrom. In this function, we try to see if have this > situation. > > A3 = B0 > ..... > ..... > B1 = A3 <--The copy C > > And if so, we check if we can merge the two ranges of B into a single range. > However, this is not safe if A3 is a subreg define while A3 is not...

...> New_MI_3:: B= REG_SEQUENCE<Vreg1, hi_sub_reg, Vreg2, lo_sub_reg> ; B > is a > 64 bit virt reg. I used this approach and it worked find until I hit, what I believe is, a bug in the register coalescer. When the register coalescer cannot trivially coalesce a copy, say C,, it calls AdjustCopiesBackFrom. In this function, we try to see if have this situation. A3 = B0 ..... ..... B1 = A3 <--The copy C And if so, we check if we can merge the two ranges of B into a single range. However, this is not safe if A3 is a subreg define while A3 is not a subreg use. For instance, consider this c...

Hi Jakob, Thanks for your reply. > > The <undef> flag goes on NewMI_1 because the virtual register B isn't live > before that instruction. > > But you probably shouldn't be doing this yourself. Your NewMI code isn't in > SSA form because B has multiple definitions. Just use a REG_SEQUENCE > instruction, and let the register allocator do the transformation

> > > That sounds like a bug, probably adjustCopiesBackFrom needs to check > ACopyMI->isFullCopy(). > > Do you have a test case for this? > > Yes and No. Yes because the example is from a unit testcase that I have. No because it manifests itself only with my half baked pass that I was talking about earlier in this thread. Pranav ---------...

On Jul 6, 2012, at 7:30 AM, Pranav D Bhandarkar <pranav.bhandarkar at utexas.edu> wrote: > That sounds like a bug, probably adjustCopiesBackFrom needs to check ACopyMI->isFullCopy(). > > Do you have a test case for this? > > > Yes and No. Yes because the example is from a unit testcase that I have. No because it manifests itself only with my half baked pass that I was talking about earlier in this thread. Alright. Eve...

Thank for your help. You're right, merging vreg32 and vreg48 is perfectly fine, sorry I missed that. I "brute force" debuged by adding MachineFunction dump after each join, I think I found the issue : it's when vreg32 and vreg10 are merged. vreg10 only appears in BB#3, and the join only occurs in BB#3 apparently even if vreg32 lives in the 4 machine blocks After joining, there

Hi Vincent, On 25/10/2012 18:14, Vincent Lejeune wrote: > When examining the debug output of regalloc, it seems that joining 32bits reg also joins 128 parent reg. > > If I look at the : > %vreg34<def> = COPY %vreg6:sel_y; R600_Reg32:%vreg34 R600_Reg128:%vreg6 > > instructions ; it gets joined to : > 928B%vreg34<def> = COPY %vreg48:sel_y; > > when vreg6 and