[Beignet] [PATCH 2/5] GBE: refine longjmp checking.

[Yang, Rong R]

One comment.

> -----Original Message-----
> From: Beignet [mailto:beignet-bounces at lists.freedesktop.org] On Behalf Of
> Zhigang Gong
> Sent: Monday, September 14, 2015 14:20
> To: beignet at lists.freedesktop.org
> Cc: Gong, Zhigang
> Subject: [Beignet] [PATCH 2/5] GBE: refine longjmp checking.
> 
> Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
> ---
>  backend/src/backend/gen_insn_selection.cpp |  2 +-
>  backend/src/ir/function.hpp                | 17 +++++++++++++++++
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/backend/src/backend/gen_insn_selection.cpp
> b/backend/src/backend/gen_insn_selection.cpp
> index ab00269..57dbec9 100644
> --- a/backend/src/backend/gen_insn_selection.cpp
> +++ b/backend/src/backend/gen_insn_selection.cpp
> @@ -1154,7 +1154,7 @@ namespace gbe
>      SelectionInstruction *insn = this->appendInsn(SEL_OP_JMPI, 0, 1);
>      insn->src(0) = src;
>      insn->index = index.value();
> -    insn->extra.longjmp = abs(index - origin) > 800;
> +    insn->extra.longjmp = ctx.getFunction().getDistance(origin, index)
> + > 8000;
>      return insn->extra.longjmp ? 2 : 1;
>    }
> 
> diff --git a/backend/src/ir/function.hpp b/backend/src/ir/function.hpp index
> b5f4ba2..b924332 100644
> --- a/backend/src/ir/function.hpp
> +++ b/backend/src/ir/function.hpp
> @@ -487,6 +487,23 @@ namespace ir {
>      Register getSurfaceBaseReg(uint8_t bti) const;
>      void appendSurface(uint8_t bti, Register reg);
>      /*! Output the control flow graph to .dot file */
> +    /*! Get instruction distance between two BBs */
> +    INLINE uint32_t getDistance(LabelIndex b0, LabelIndex b1) const {
> +      int start, end;
> +      if (b0.value() < b1.value()) {
> +        start = b0.value();
> +        end = b1.value() - 1;
> +      } else {
> +        start = b1.value();
> +        end = b0.value() - 1;
> +      }
> +      uint32_t insnNum = 0;
> +      for(int i = start; i <= end; i++) {
> +        BasicBlock &bb = getBlock(LabelIndex(i));
> +        insnNum += bb.size();
> +      }
If front jump, need not include the start and end block's size.

> +      return insnNum;
> +    }
>      void outputCFG();
>    private:
>      friend class Context;           //!< Can freely modify a function
> --
> 1.9.1
> 
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