[PATCH, rs6000] (2/3) Fix widening multiply high/low operations for little endian

[Bill Schmidt]

Per Richard S's suggestion, I'm reworking parts 1 and 3 of the patch
set, but this one will remain unchanged and is ready for review.

Thanks,
Bill

On Sun, 2013-11-03 at 23:34 -0600, Bill Schmidt wrote:
> Hi,
> 
> This patch fixes the widening multiply high/low operations to work
> correctly in the presence of the first patch of this series, which
> reverses the meanings of multiply even/odd instructions.  Here we
> reorder the input operands to the vector merge low/high instructions.
> 
> The general rule is that vmrghh(x,y) [BE] = vmrglh(y,x) [LE], and so on;
> that is, we need to reverse the usage of merge high and merge low, and
> also swap their inputs, to obtain the same semantics.  In this case we
> are only swapping the inputs, because the reversed usage of high and low
> has already been done for us in the generic handling code for
> VEC_WIDEN_MULT_LO_EXPR.
> 
> Bootstrapped and tested with the rest of the patch set on
> powerpc64{,le}-unknown-linux-gnu, with no regressions.  Is this ok for
> trunk?
> 
> Thanks,
> Bill
> 
> 
> 2013-11-03  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
> 
> 	* config/rs6000/altivec.md (vec_widen_umult_hi_v16qi): Swap
> 	arguments to merge instruction for little endian.
> 	(vec_widen_umult_lo_v16qi): Likewise.
> 	(vec_widen_smult_hi_v16qi): Likewise.
> 	(vec_widen_smult_lo_v16qi): Likewise.
> 	(vec_widen_umult_hi_v8hi): Likewise.
> 	(vec_widen_umult_lo_v8hi): Likewise.
> 	(vec_widen_smult_hi_v8hi): Likewise.
> 	(vec_widen_smult_lo_v8hi): Likewise.
> 
> 
> Index: gcc/config/rs6000/altivec.md
> ===================================================================
> --- gcc/config/rs6000/altivec.md	(revision 204192)
> +++ gcc/config/rs6000/altivec.md	(working copy)
> @@ -2185,7 +2235,10 @@
>    
>    emit_insn (gen_vec_widen_umult_even_v16qi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_umult_odd_v16qi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrghh (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrghh (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrghh (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2202,7 +2255,10 @@
>    
>    emit_insn (gen_vec_widen_umult_even_v16qi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_umult_odd_v16qi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrglh (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrglh (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrglh (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2219,7 +2275,10 @@
>    
>    emit_insn (gen_vec_widen_smult_even_v16qi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_smult_odd_v16qi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrghh (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrghh (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrghh (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2236,7 +2295,10 @@
>    
>    emit_insn (gen_vec_widen_smult_even_v16qi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_smult_odd_v16qi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrglh (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrglh (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrglh (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2253,7 +2315,10 @@
>    
>    emit_insn (gen_vec_widen_umult_even_v8hi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_umult_odd_v8hi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrghw (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrghw (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrghw (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2270,7 +2335,10 @@
>    
>    emit_insn (gen_vec_widen_umult_even_v8hi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_umult_odd_v8hi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrglw (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrglw (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrglw (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2287,7 +2355,10 @@
>    
>    emit_insn (gen_vec_widen_smult_even_v8hi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_smult_odd_v8hi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrghw (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrghw (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrghw (operands[0], vo, ve));
>    DONE;
>  }")
> 
> @@ -2304,7 +2375,10 @@
>    
>    emit_insn (gen_vec_widen_smult_even_v8hi (ve, operands[1], operands[2]));
>    emit_insn (gen_vec_widen_smult_odd_v8hi (vo, operands[1], operands[2]));
> -  emit_insn (gen_altivec_vmrglw (operands[0], ve, vo));
> +  if (BYTES_BIG_ENDIAN)
> +    emit_insn (gen_altivec_vmrglw (operands[0], ve, vo));
> +  else
> +    emit_insn (gen_altivec_vmrglw (operands[0], vo, ve));
>    DONE;
>  }")
> 
> 
>