The vec_perm code falls back to doing byte-level permutes if
element-level permutes aren't supported. There were two copies
of the code to calculate the mode, and later patches add another,
so this patch splits it out into a helper function.
2017-12-09 Richard Sandiford <richard.sandif...@linaro.org>
gcc/
* optabs-query.h (qimode_for_vec_perm): Declare.
* optabs-query.c (can_vec_perm_p): Split out qimode search to...
(qimode_for_vec_perm): ...this new function.
* optabs.c (expand_vec_perm): Use qimode_for_vec_perm.
Index: gcc/optabs-query.h
===================================================================
--- gcc/optabs-query.h 2017-12-09 22:47:12.476364764 +0000
+++ gcc/optabs-query.h 2017-12-09 22:47:14.730310076 +0000
@@ -174,6 +174,7 @@ enum insn_code can_extend_p (machine_mod
enum insn_code can_float_p (machine_mode, machine_mode, int);
enum insn_code can_fix_p (machine_mode, machine_mode, int, bool *);
bool can_conditionally_move_p (machine_mode mode);
+opt_machine_mode qimode_for_vec_perm (machine_mode);
bool can_vec_perm_p (machine_mode, bool, vec_perm_indices *);
/* Find a widening optab even if it doesn't widen as much as we want. */
#define find_widening_optab_handler(A, B, C) \
Index: gcc/optabs-query.c
===================================================================
--- gcc/optabs-query.c 2017-12-09 22:47:12.476364764 +0000
+++ gcc/optabs-query.c 2017-12-09 22:47:14.729310075 +0000
@@ -345,6 +345,22 @@ can_conditionally_move_p (machine_mode m
return direct_optab_handler (movcc_optab, mode) != CODE_FOR_nothing;
}
+/* If a target doesn't implement a permute on a vector with multibyte
+ elements, we can try to do the same permute on byte elements.
+ If this makes sense for vector mode MODE then return the appropriate
+ byte vector mode. */
+
+opt_machine_mode
+qimode_for_vec_perm (machine_mode mode)
+{
+ machine_mode qimode;
+ if (GET_MODE_INNER (mode) != QImode
+ && mode_for_vector (QImode, GET_MODE_SIZE (mode)).exists (&qimode)
+ && VECTOR_MODE_P (qimode))
+ return qimode;
+ return opt_machine_mode ();
+}
+
/* Return true if VEC_PERM_EXPR of arbitrary input vectors can be
expanded using SIMD extensions of the CPU. SEL may be NULL, which
stands for an unknown constant. Note that additional permutations
@@ -375,9 +391,7 @@ can_vec_perm_p (machine_mode mode, bool
return true;
/* We allow fallback to a QI vector mode, and adjust the mask. */
- if (GET_MODE_INNER (mode) == QImode
- || !mode_for_vector (QImode, GET_MODE_SIZE (mode)).exists (&qimode)
- || !VECTOR_MODE_P (qimode))
+ if (!qimode_for_vec_perm (mode).exists (&qimode))
return false;
/* ??? For completeness, we ought to check the QImode version of
Index: gcc/optabs.c
===================================================================
--- gcc/optabs.c 2017-12-09 22:47:12.476364764 +0000
+++ gcc/optabs.c 2017-12-09 22:47:14.731310077 +0000
@@ -5452,9 +5452,7 @@ expand_vec_perm (machine_mode mode, rtx
/* Set QIMODE to a different vector mode with byte elements.
If no such mode, or if MODE already has byte elements, use VOIDmode. */
- if (GET_MODE_INNER (mode) == QImode
- || !mode_for_vector (QImode, w).exists (&qimode)
- || !VECTOR_MODE_P (qimode))
+ if (!qimode_for_vec_perm (mode).exists (&qimode))
qimode = VOIDmode;
/* If the input is a constant, expand it specially. */
