[Beignet] [PATCH] GBE: Fix live range for temporary register in replaceReg

[Zhigang Gong]

Good catch, ruiling. Just pushed, thanks.

On Tue, Nov 04, 2014 at 03:22:40PM +0800, Ruiling Song wrote:
> previously it is simply assigned as [insnID, insnID], But it is used in 2 instruction:
> [1] MOV tmp, replacedReg
> [2] send null, addr, tmp,...
> 
> As minID maxID is equal, it will be treated as temporary register during spill,
> and no scratch memory allocated. But scratch register is allocated per instruction,
> if tmp in [1] is assigned g100 from spill register pool, instruction [2] would have no idea of that,
> it will assign another register like g102 from spill register pool. As no scratch memory allocated,
> we cannnot do any spill/unspill operation between them.
> 
> To fix this issue, I change the liveness range according to isSrc, so spill/unspill
> could work as normally.
> 
> This patch fix the cos16 test case failure in piglit under strict conformance.
> 
> Signed-off-by: Ruiling Song <ruiling.song at intel.com>
> ---
>  backend/src/backend/gen_reg_allocation.cpp |   14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/backend/src/backend/gen_reg_allocation.cpp b/backend/src/backend/gen_reg_allocation.cpp
> index a57edb3..ef519d9 100644
> --- a/backend/src/backend/gen_reg_allocation.cpp
> +++ b/backend/src/backend/gen_reg_allocation.cpp
> @@ -194,13 +194,17 @@ namespace gbe
>                                     uint32_t regID, bool isSrc,
>                                     ir::Type type = ir::TYPE_FLOAT, bool needMov = true) {
>        ir::Register reg;
> -      if (isSrc)
> +      if (isSrc) {
>          reg = sel.replaceSrc(insn, regID, type, needMov);
> -      else
> +        intervals.push_back(reg);
> +        intervals[reg].minID = insn->ID - 1;
> +        intervals[reg].maxID = insn->ID;
> +      } else {
>          reg = sel.replaceDst(insn, regID, type, needMov);
> -      intervals.push_back(reg);
> -      intervals[reg].minID = insn->ID;
> -      intervals[reg].maxID = insn->ID;
> +        intervals.push_back(reg);
> +        intervals[reg].minID = insn->ID;
> +        intervals[reg].maxID = insn->ID + 1;
> +      }
>        return reg;
>      }
>      /*! Use custom allocator */
> -- 
> 1.7.10.4
> 
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