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vect: Fix epilogue mode skipping

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gcc/ChangeLog:

	PR tree-optimization/103997
	* tree-vect-loop.cc (vect_analyze_loop): Fix mode skipping for epilogue
	vectorization.
This commit is contained in:
Andre Vieira
2022-01-19 14:11:32 +00:00
parent ffc7f200ad
commit f4ca0a53be
1 changed files with 19 additions and 5 deletions
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24
gcc/tree-vect-loop.cc
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@@ -3004,6 +3004,12 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
unsigned int mode_i = 0;
unsigned HOST_WIDE_INT simdlen = loop->simdlen;
/* Keep track of the VF for each mode. Initialize all to 0 which indicates
a mode has not been analyzed. */
auto_vec<poly_uint64, 8> cached_vf_per_mode;
for (unsigned i = 0; i < vector_modes.length (); ++i)
cached_vf_per_mode.safe_push (0);
/* First determine the main loop vectorization mode, either the first
one that works, starting with auto-detecting the vector mode and then
following the targets order of preference, or the one with the
@@ -3011,6 +3017,10 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
while (1)
{
bool fatal;
unsigned int last_mode_i = mode_i;
/* Set cached VF to -1 prior to analysis, which indicates a mode has
failed. */
cached_vf_per_mode[last_mode_i] = -1;
opt_loop_vec_info loop_vinfo
= vect_analyze_loop_1 (loop, shared, &loop_form_info,
NULL, vector_modes, mode_i,
@@ -3020,6 +3030,12 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
if (loop_vinfo)
{
/* Analyzis has been successful so update the VF value. The
VF should always be a multiple of unroll_factor and we want to
capture the original VF here. */
cached_vf_per_mode[last_mode_i]
= exact_div (LOOP_VINFO_VECT_FACTOR (loop_vinfo),
loop_vinfo->suggested_unroll_factor);
/* Once we hit the desired simdlen for the first time,
discard any previous attempts. */
if (simdlen
@@ -3100,12 +3116,10 @@ vect_analyze_loop (class loop *loop, vec_info_shared *shared)
{
/* If the target does not support partial vectors we can shorten the
number of modes to analyze for the epilogue as we know we can't pick a
mode that has at least as many NUNITS as the main loop's vectorization
factor, since that would imply the epilogue's vectorization factor
would be at least as high as the main loop's and we would be
vectorizing for more scalar iterations than there would be left. */
mode that would lead to a VF at least as big as the
FIRST_VINFO_VF. */
if (!supports_partial_vectors
&& maybe_ge (GET_MODE_NUNITS (vector_modes[mode_i]), first_vinfo_vf))
&& maybe_ge (cached_vf_per_mode[mode_i], first_vinfo_vf))
{
mode_i++;
if (mode_i == vector_modes.length ())