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[RS6000] power8 unaligned fp load/store

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According to the POWER8 Processor User’s Manual and some
experimentation on power8 hardware, unaligned fp load/store on power8
does not invoke the alignment interrupt.

	* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Make scalar
	float access depend on TARGET_EFFICIENT_UNALIGNED_VSX.
	* config/rs6000/rs6000.opt (-mefficient-unaligned-vsx): Renamed
	from -mefficient-unaligned-vector.  Note that this affects fp too.

From-SVN: r239013
This commit is contained in:
Alan Modra 2016-08-03 10:12:06 +09:30 • committed by Alan Modra
parent cef58349a0
commit 860271ec6c
3 changed files with 13 additions and 6 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2016-08-03 Alan Modra <amodra@gmail.com>
* config/rs6000/rs6000.h (SLOW_UNALIGNED_ACCESS): Make scalar
float access depend on TARGET_EFFICIENT_UNALIGNED_VSX.
* config/rs6000/rs6000.opt (-mefficient-unaligned-vsx): Renamed
from -mefficient-unaligned-vector. Note that this affects fp too.
2016-08-03 Alan Modra <amodra@gmail.com>
* config/rs6000/rs6000.c (rs6000_rtx_costs): Make unaligned mem

8
gcc/config/rs6000/rs6000.h
View file

@ -990,10 +990,10 @@ enum data_align { align_abi, align_opt, align_both };
aligned to 4 or 8 bytes. */
#define SLOW_UNALIGNED_ACCESS(MODE, ALIGN) \
(STRICT_ALIGNMENT \
|| (SCALAR_FLOAT_MODE_NOT_VECTOR_P (MODE) && (ALIGN) < 32) \
|| (!TARGET_EFFICIENT_UNALIGNED_VSX \
&& ((VECTOR_MODE_P (MODE) || FLOAT128_VECTOR_P (MODE)) \
&& (((int)(ALIGN)) < VECTOR_ALIGN (MODE)))))
|| (!TARGET_EFFICIENT_UNALIGNED_VSX \
&& ((SCALAR_FLOAT_MODE_NOT_VECTOR_P (MODE) && (ALIGN) < 32) \
|| ((VECTOR_MODE_P (MODE) || FLOAT128_VECTOR_P (MODE)) \
&& (int) (ALIGN) < VECTOR_ALIGN (MODE)))))
/* Standard register usage. */

4
gcc/config/rs6000/rs6000.opt
View file

@ -211,9 +211,9 @@ mallow-movmisalign
Target Undocumented Var(TARGET_ALLOW_MOVMISALIGN) Init(-1) Save
; Allow the movmisalign in DF/DI vectors
mefficient-unaligned-vector
mefficient-unaligned-vsx
Target Undocumented Report Mask(EFFICIENT_UNALIGNED_VSX) Var(rs6000_isa_flags)
; Consider unaligned VSX accesses to be efficient
; Consider unaligned VSX vector and fp accesses to be efficient
mallow-df-permute
Target Undocumented Var(TARGET_ALLOW_DF_PERMUTE) Save