[Beignet] [PATCH] libocl: Directly scalarize built-in with vector input.

[Zhigang Gong]

This patch LGTM. Actually, after the sin/cos functions have been optimized,
we don't need to fold those vector operations into a for loop.

Will push it latter. Thanks.

On Sun, Feb 15, 2015 at 04:09:07PM +0800, Ruiling Song wrote:
> This revert the following commit:
> "Re-apply "improve the build performance of vector type built-in function.""
> commitId: 06cce8178649759e12a3a353f0550189d371871b.
> 
> I finally decide to do this because although below kind of program has less
> instructions and less compile-time, but it will also introduce extra memory access,
> which would cause bad run-time performance if the loop is not unrolled. If the loop
> is unrolled, it would be similar like scalarized version.
> 
> OVERLOADABLE float16 func (float16 param0)
> {
>   union{
>     float va[16];
>     float16 vv16;
>   }uret;
>   union{
>     float pa[16];
>     float16 pv16;
>   }usrc0;
>   usrc0.pv16 = param0;
>   for(int i =0; i < 16; i++)
>     uret.va[i] = func(usrc0.pa[i]);
>  return uret.vv16;
> }
> 
> I did some experiment on the affected built-in. I fixed the GPU frequency at 1050,
> and increase input data to 862000. The result is like below (obviously the scalarized
> version has better performance):
> 
> bultin_asinh_float16:
> loop version:      200ms
> scalarized version: 150ms
> 
> builtin_sinh_float16:
> loop version:      250ms
> scalarized version: 160ms
> 
> And also this patch would reduce the generation of large integer. Although we support
> large integer legalization, I find sometime it is hard to legalize in very efficient way
> like large integer LE/GT.
> ---
>  backend/src/libocl/script/gen_vector.py |   45 +++++--------------------------
>  1 file changed, 6 insertions(+), 39 deletions(-)
> 
> diff --git a/backend/src/libocl/script/gen_vector.py b/backend/src/libocl/script/gen_vector.py
> index 291dd87..ffc573a 100755
> --- a/backend/src/libocl/script/gen_vector.py
> +++ b/backend/src/libocl/script/gen_vector.py
> @@ -289,42 +289,9 @@ class builtinProto():
>              formatStr += ';'
>              self.append(formatStr)
>              return formatStr
> -        if self.functionName != 'select' and ptypeSeqs[0] == ptypeSeqs[self.paramCount-1] and ptype[1] > 4:
> -            formatStr += '\n{ \n  union{'
> -            formatStr = self.append(formatStr, '    {0} va[{1}];'.format(vtype[0], vtype[1]))
> -            formatStr = self.append(formatStr, '    {0}{1} vv{2};'.format(vtype[0], vtype[1], vtype[1]))
> -            formatStr += '\n  }uret;'
> -            formatStr += '\n  union{'
> -            formatStr = self.append(formatStr, '    {0} pa[{1}];'.format(ptype[0], ptype[1]))
> -            formatStr = self.append(formatStr, '    {0}{1} pv{2};'.format(ptype[0], ptype[1], ptype[1]))
> -            formatStr += '\n  }'
> -            for n in range(0, self.paramCount):
> -              formatStr += 'usrc{0}'.format(n)
> -              if n+1 != self.paramCount:
> -                formatStr +=', '
> -            formatStr += ';'
> -
> -            for n in range(0, self.paramCount):
> -              formatStr = self.append(formatStr, '  usrc{0}.pv{1} = param{2};'.format(n, ptype[1], n))
> -            formatStr = self.append(formatStr, '  for(int i =0; i < {0}; i++)'.format(ptype[1]))
> -            formatStr += '\n    uret.va[i] = '
> -            if self.prefix == 'relational' and self.functionName != 'bitselect' and self.functionName != 'select':
> -              formatStr += '-'
> -            formatStr += '{0}('.format(self.functionName)
> -
> -            for n in range(0, self.paramCount):
> -              formatStr += 'usrc{0}.pa[i]'.format(n)
> -              if n+1 != self.paramCount:
> -                formatStr +=', '
> -            formatStr += ');'
> -            formatStr = self.append(formatStr, ' return uret.vv{0};'.format(vtype[1]))
> -            formatStr += '\n}'
> -            formatStr = self.append(formatStr)
> -            return formatStr
> -        else:
> -          formatStr = self.append(formatStr, '{{return ({0}{1})('.format(vtype[0], vtype[1]))
> -          self.indent = len(formatStr)
> -          for j in range(0, vtype[1]):
> +        formatStr = self.append(formatStr, '{{return ({0}{1})('.format(vtype[0], vtype[1]))
> +        self.indent = len(formatStr)
> +        for j in range(0, vtype[1]):
>              if (j != 0):
>                  formatStr += ','
>                  if (j + 1) % 2 == 0:
> @@ -359,10 +326,10 @@ class builtinProto():
>  
>              formatStr += ')'
>  
> -          formatStr += '); }\n'
> -          self.append(formatStr)
> +        formatStr += '); }\n'
> +        self.append(formatStr)
>  
> -          return formatStr
> +        return formatStr
>  
>      def output(self):
>          for line in self.outputStr:
> -- 
> 1.7.10.4
> 
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