From: Ju-Zhe Zhong <juzhe.zh...@rivai.ai>
Hi, Richard and Richi.
This patch add support live vectorization by VEC_EXTRACT for LEN loop control.
Consider this following case:
#include <stdint.h>
#define EXTRACT_LAST(TYPE) \
TYPE __attribute__ ((noinline, noclone)) \
test_##TYPE (TYPE *x, int n, TYPE value) \
{ \
TYPE last; \
for (int j = 0; j < n; ++j) \
{ \
last = x[j]; \
x[j] = last * value; \
} \
return last; \
}
#define TEST_ALL(T) \
T (uint8_t) \
TEST_ALL (EXTRACT_LAST)
ARM SVE IR:
Preheader:
max_mask_34 = .WHILE_ULT (0, bnd.5_6, { 0, ... });
Loop:
...
# loop_mask_22 = PHI <next_mask_35(4), max_mask_34(3)>
...
vect_last_12.8_23 = .MASK_LOAD (_7, 8B, loop_mask_22);
vect__4.9_27 = vect_last_12.8_23 * vect_cst__26;
.MASK_STORE (_7, 8B, loop_mask_22, vect__4.9_27);
...
next_mask_35 = .WHILE_ULT (_1, bnd.5_6, { 0, ... });
...
Epilogue:
_25 = .EXTRACT_LAST (loop_mask_22, vect_last_12.8_23);
For RVV since we prefer len in loop control, after this patch for RVV:
Loop:
...
loop_len_22 = SELECT_VL;
vect_last_12.8_23 = .MASK_LOAD (_7, 8B, loop_len_22);
vect__4.9_27 = vect_last_12.8_23 * vect_cst__26;
.MASK_STORE (_7, 8B, loop_len_22, vect__4.9_27);
...
Epilogue:
_25 = .VEC_EXTRACT (loop_len_22 - 1 - bias, vect_last_12.8_23);
Details of this approach:
1. Step 1 - Add 'vect_can_vectorize_extract_last_with_len_p' to enable live
vectorization
for LEN loop control.
This function we check whether target support:
- Use LEN as the loop control.
- Support VEC_EXTRACT optab.
2. Step 2 - Record LEN for loop control if
'vect_can_vectorize_extract_last_with_len_p' is true.
3. Step 3 - Gerenate VEC_EXTRACT (v, LEN - 1 - BIAS).
NOTE: This patch set 'vinfo->any_known_not_updated_vssa = true;' since the
original STMT is a simple
assignment wheras VEC_EXTRACT is neither pure nor const function
according to internal-fn.def:
DEF_INTERNAL_OPTAB_FN (VEC_EXTRACT, 0, vec_extract, vec_extract)
If we don't set 'vinfo->any_known_not_updated_vssa' as true, it will
cause ICE in:
if (need_ssa_update_p (cfun))
{
gcc_assert (loop_vinfo->any_known_not_updated_vssa); ----> Report
assertion fail here.
fun->gimple_df->ssa_renaming_needed = false;
todo |= TODO_update_ssa_only_virtuals;
}
I saw there are 2 places set 'vinfo->any_known_not_updated_vssa' as true:
- The one is in 'vectorizable_simd_clone_call':
/* When the original call is pure or const but the SIMD ABI dictates
an aggregate return we will have to use a virtual definition and
in a loop eventually even need to add a virtual PHI. That's
not straight-forward so allow to fix this up via renaming. */
if (gimple_call_lhs (stmt)
&& !gimple_vdef (stmt)
&& TREE_CODE (TREE_TYPE (TREE_TYPE (bestn->decl))) == ARRAY_TYPE)
vinfo->any_known_not_updated_vssa = true;
- The other is in 'vectorizable_load':
if (memory_access_type == VMAT_LOAD_STORE_LANES)
vinfo->any_known_not_updated_vssa = true;
It seems that they are the same reason as me doing in
'vectorizable_live_operation'.
Feel free to correct me if I am wrong.
Bootstrap and Regression on X86 passed.
gcc/ChangeLog:
* tree-vect-loop.cc (vect_can_vectorize_extract_last_with_len_p): New
function.
(vectorizable_live_operation): Add loop LEN control.
---
gcc/tree-vect-loop.cc | 74 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 68 insertions(+), 6 deletions(-)
diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 00058c3c13e..208918f53fb 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -8964,6 +8964,24 @@ vect_can_vectorize_without_simd_p (code_helper code)
&& vect_can_vectorize_without_simd_p (tree_code (code)));
}
+/* Return true if target supports extract last vectorization with LEN. */
+
+static bool
+vect_can_vectorize_extract_last_with_len_p (tree vectype)
+{
+ /* Return false if target doesn't support LEN in loop control. */
+ machine_mode vmode;
+ if (!get_len_load_store_mode (TYPE_MODE (vectype), true).exists (&vmode)
+ || !get_len_load_store_mode (TYPE_MODE (vectype), false).exists (&vmode))
+ return false;
+
+ /* Target need to support VEC_EXTRACT to extract the last active element. */
+ return convert_optab_handler (vec_extract_optab,
+ TYPE_MODE (vectype),
+ TYPE_MODE (TREE_TYPE (vectype)))
+ != CODE_FOR_nothing;
+}
+
/* Create vector init for vectorized iv. */
static tree
vect_create_nonlinear_iv_init (gimple_seq* stmts, tree init_expr,
@@ -10282,7 +10300,8 @@ vectorizable_live_operation (vec_info *vinfo,
if (loop_vinfo && LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
{
if (!direct_internal_fn_supported_p (IFN_EXTRACT_LAST, vectype,
- OPTIMIZE_FOR_SPEED))
+ OPTIMIZE_FOR_SPEED)
+ && !vect_can_vectorize_extract_last_with_len_p (vectype))
{
if (dump_enabled_p ())
dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -10311,9 +10330,14 @@ vectorizable_live_operation (vec_info *vinfo,
else
{
gcc_assert (ncopies == 1 && !slp_node);
- vect_record_loop_mask (loop_vinfo,
- &LOOP_VINFO_MASKS (loop_vinfo),
- 1, vectype, NULL);
+ if (vect_can_vectorize_extract_last_with_len_p (vectype))
+ vect_record_loop_len (loop_vinfo,
+ &LOOP_VINFO_LENS (loop_vinfo),
+ 1, vectype, 1);
+ else
+ vect_record_loop_mask (loop_vinfo,
+ &LOOP_VINFO_MASKS (loop_vinfo),
+ 1, vectype, NULL);
}
}
/* ??? Enable for loop costing as well. */
@@ -10339,7 +10363,9 @@ vectorizable_live_operation (vec_info *vinfo,
gimple *vec_stmt;
if (slp_node)
{
- gcc_assert (!loop_vinfo || !LOOP_VINFO_FULLY_MASKED_P (loop_vinfo));
+ gcc_assert (!loop_vinfo
+ || (!LOOP_VINFO_FULLY_MASKED_P (loop_vinfo)
+ && !LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo)));
/* Get the correct slp vectorized stmt. */
vec_lhs = SLP_TREE_VEC_DEFS (slp_node)[vec_entry];
@@ -10383,7 +10409,43 @@ vectorizable_live_operation (vec_info *vinfo,
gimple_seq stmts = NULL;
tree new_tree;
- if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
+ if (LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo))
+ {
+ /* Emit:
+
+ SCALAR_RES = VEC_EXTRACT <VEC_LHS, LEN - BIAS - 1>
+
+ where VEC_LHS is the vectorized live-out result and MASK is
+ the loop mask for the final iteration. */
+ gcc_assert (ncopies == 1 && !slp_node);
+ tree scalar_type = TREE_TYPE (STMT_VINFO_VECTYPE (stmt_info));
+ tree len
+ = vect_get_loop_len (loop_vinfo, gsi, &LOOP_VINFO_LENS (loop_vinfo),
+ 1, vectype, 0, 0);
+
+ /* BIAS + 1. */
+ signed char biasval = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
+ tree bias_one
+ = size_binop (PLUS_EXPR, build_int_cst (TREE_TYPE (len), biasval),
+ build_one_cst (TREE_TYPE (len)));
+
+ /* LAST_INDEX = LEN - (BIAS + 1). */
+ tree last_index
+ = gimple_build (&stmts, MINUS_EXPR, TREE_TYPE (len), len, bias_one);
+
+ tree scalar_res = gimple_build (&stmts, CFN_VEC_EXTRACT, scalar_type,
+ vec_lhs_phi, last_index);
+
+ /* Convert the extracted vector element to the scalar type. */
+ new_tree = gimple_convert (&stmts, lhs_type, scalar_res);
+ /* When the original stmt is an assignment but VEC_EXTRACT is not pure
+ or const since it may return a memory result. We will have to use
+ a virtual definition and in a loop eventually even need to add a
+ virtual PHI. That's not straight-forward so allow to fix this up
+ via renaming. */
+ vinfo->any_known_not_updated_vssa = true;
+ }
+ else if (LOOP_VINFO_FULLY_MASKED_P (loop_vinfo))
{
/* Emit:
--
2.36.3
