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rs6000.h (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED): Add macro to say we can efficiently handle overlapping unaligned loads. 

2016-10-09  Aaron Sawdey  <acsawdey@linux.vnet.ibm.com>

	* config/rs6000/rs6000.h (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED): 
	Add macro to say we can efficiently handle overlapping unaligned
	loads.
	* config/rs6000/rs6000.c (expand_block_compare): Avoid generating
	poor code for processors older than p8.

From-SVN: r240908
This commit is contained in:
Aaron Sawdey 2016-10-10 04:42:08 +00:00 committed by Aaron Sawdey
parent 4815e7d405
commit 87b44b83c0
3 changed files with 33 additions and 4 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2016-10-09 Aaron Sawdey <acsawdey@linux.vnet.ibm.com>
* config/rs6000/rs6000.h (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED):
Add macro to say we can efficiently handle overlapping unaligned
loads.
* config/rs6000/rs6000.c (expand_block_compare): Avoid generating
poor code for processors older than p8.
2016-10-09 Eric Botcazou <ebotcazou@adacore.com>
* gen-pass-instances.awk: Remove GNUism.

26
gcc/config/rs6000/rs6000.c
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@ -18771,6 +18771,14 @@ expand_block_compare (rtx operands[])
if (bytes <= 0)
return true;
/* The code generated for p7 and older is not faster than glibc
memcmp if alignment is small and length is not short, so bail
out to avoid those conditions. */
if (!TARGET_EFFICIENT_OVERLAPPING_UNALIGNED
&& ((base_align == 1 && bytes > 16)
|| (base_align == 2 && bytes > 32)))
return false;
rtx tmp_reg_src1 = gen_reg_rtx (word_mode);
rtx tmp_reg_src2 = gen_reg_rtx (word_mode);
@ -18820,13 +18828,18 @@ expand_block_compare (rtx operands[])
while (bytes > 0)
{
int align = compute_current_alignment (base_align, offset);
load_mode = select_block_compare_mode(offset, bytes, align, word_mode_ok);
if (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED)
load_mode = select_block_compare_mode (offset, bytes, align,
word_mode_ok);
else
load_mode = select_block_compare_mode (0, bytes, align, word_mode_ok);
load_mode_size = GET_MODE_SIZE (load_mode);
if (bytes >= load_mode_size)
cmp_bytes = load_mode_size;
else
else if (TARGET_EFFICIENT_OVERLAPPING_UNALIGNED)
{
/* Move this load back so it doesn't go past the end. */
/* Move this load back so it doesn't go past the end.
P8/P9 can do this efficiently. */
int extra_bytes = load_mode_size - bytes;
cmp_bytes = bytes;
if (extra_bytes < offset)
@ -18836,7 +18849,12 @@ expand_block_compare (rtx operands[])
bytes = cmp_bytes;
}
}
else
/* P7 and earlier can't do the overlapping load trick fast,
so this forces a non-overlapping load and a shift to get
rid of the extra bytes. */
cmp_bytes = bytes;
src1 = adjust_address (orig_src1, load_mode, offset);
src2 = adjust_address (orig_src2, load_mode, offset);

3
gcc/config/rs6000/rs6000.h
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@ -607,6 +607,9 @@ extern int rs6000_vector_align[];
&& TARGET_POWERPC64)
#define TARGET_VEXTRACTUB (TARGET_P9_VECTOR && TARGET_DIRECT_MOVE \
&& TARGET_UPPER_REGS_DI && TARGET_POWERPC64)
/* This wants to be set for p8 and newer. On p7, overlapping unaligned
loads are slow. */
#define TARGET_EFFICIENT_OVERLAPPING_UNALIGNED TARGET_EFFICIENT_UNALIGNED_VSX
/* Byte/char syncs were added as phased in for ISA 2.06B, but are not present
in power7, so conditionalize them on p8 features. TImode syncs need quad