Hi
Enable GIMPLE folding of the vec_splat() intrinsic.
For review.. feedback is expected. :-)
I came up with the following after spending some time poking around
at the tree_vec_extract() and vector_element() functions as seen
in tree-vect-generic.c looking for insights. Some of this seems a
bit clunky to me yet, but this is functional as far as make-check
can tell, and is as far as I can get without additional input.
This uses the tree_vec_extract() function out of tree-vect-generic.c
to retrieve the splat value, which is a BIT_FIELD_REF. That function is
made non-static as part of this change.
In review of the .gimple output, this folding takes a sample testcase
of
vector bool int testb_0 (vector bool int x)
{
return vec_splat (x, 0b00000);
}
from:
testb_0 (__vector __bool int x)
{
__vector __bool intD.1486 D.2855;
_1 = VIEW_CONVERT_EXPR<__vector signed intD.1468>(xD.2778);
_2 = __builtin_altivec_vspltwD.1919 (_1, 0);
D.2855 = VIEW_CONVERT_EXPR<__vector __bool intD.1486>(_2);
return D.2855;
}
to:
testb_0 (__vector __bool int x)
{
__vector __bool intD.1486 D.2855;
_1 = VIEW_CONVERT_EXPR<__vector signed intD.1468>(xD.2778);
D.2856 = BIT_FIELD_REF <_1, 32, 0>;
_2 = {D.2856, D.2856, D.2856, D.2856};
D.2855 = VIEW_CONVERT_EXPR<__vector __bool intD.1486>(_2);
return D.2855;
}
Testcases are being posted as a separate patch.
OK for trunk?
Thanks,
-Will
[gcc]
2018-08-07 Will Schmidt <will_schm...@vnet.ibm.com>
* config/rs6000/rs6000.c (rs6000_gimple_fold_builtin): Add support for
early gimple folding of vec_splat().
* tree-vect-generic.c: Remove static from tree_vec_extract() definition.
* gimple-fold.h: Add an extern define for tree_vec_extract().
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 35c32be..acc6b49 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -15764,10 +15764,56 @@ rs6000_gimple_fold_builtin (gimple_stmt_iterator *gsi)
tree splat_tree = build_vector_from_val (TREE_TYPE (lhs), splat_value);
g = gimple_build_assign (lhs, splat_tree);
gimple_set_location (g, gimple_location (stmt));
gsi_replace (gsi, g, true);
return true;
+ }
+
+ /* Flavors of vec_splat. */
+ // a = vec_splat (b, 0x3) ; // a = { b[3],b[3],b[3],...};
+ case ALTIVEC_BUILTIN_VSPLTB:
+ case ALTIVEC_BUILTIN_VSPLTH:
+ case ALTIVEC_BUILTIN_VSPLTW:
+ case VSX_BUILTIN_XXSPLTD_V2DI:
+ case VSX_BUILTIN_XXSPLTD_V2DF:
+ {
+ arg0 = gimple_call_arg (stmt, 0); /* input vector. */
+ arg1 = gimple_call_arg (stmt, 1); /* index into arg0. */
+ /* Only fold the vec_splat_*() if arg1 is a constant
+ 5-bit unsigned literal. */
+ if (TREE_CODE (arg1) != INTEGER_CST || TREE_INT_CST_LOW (arg1) > 0x1f)
+ return false;
+
+ lhs = gimple_call_lhs (stmt);
+ tree lhs_type = TREE_TYPE (lhs);
+
+ tree splat;
+ if (TREE_CODE (arg0) == VECTOR_CST)
+ splat = VECTOR_CST_ELT (arg0, TREE_INT_CST_LOW (arg1));
+ else
+ {
+ /* Determine (in bits) the length and start location of the
+ splat value for a call to the tree_vec_extract helper. */
+ int tree_size_in_bits = TREE_INT_CST_LOW (size_in_bytes (lhs_type))
+ * BITS_PER_UNIT;
+ int splat_elem_size = tree_size_in_bits / VECTOR_CST_NELTS (arg0);
+ int splat_start_bit = TREE_INT_CST_LOW (arg1) * splat_elem_size;
+ /* Do not attempt to early-fold if the size + specified offset into
+ the vector would touch outside of the source vector. */
+ if ((splat_start_bit + splat_elem_size) > tree_size_in_bits)
+ return false;
+ tree len = build_int_cst (bitsizetype, splat_elem_size);
+ tree start = build_int_cst (bitsizetype, splat_start_bit);
+ splat = tree_vec_extract (gsi, TREE_TYPE (lhs_type), arg0,
+ len, start);
+ }
+ /* And finally, build the new vector. */
+ tree splat_tree = build_vector_from_val (lhs_type, splat);
+ g = gimple_build_assign (lhs, splat_tree);
+ gimple_set_location (g, gimple_location (stmt));
+ gsi_replace (gsi, g, true);
+ return true;
}
/* vec_mergel (integrals). */
case ALTIVEC_BUILTIN_VMRGLH:
case ALTIVEC_BUILTIN_VMRGLW:
diff --git a/gcc/gimple-fold.h b/gcc/gimple-fold.h
index 04e9bfa..e634180 100644
--- a/gcc/gimple-fold.h
+++ b/gcc/gimple-fold.h
@@ -59,10 +59,11 @@ extern tree gimple_fold_indirect_ref (tree);
extern bool gimple_fold_builtin_sprintf (gimple_stmt_iterator *);
extern bool gimple_fold_builtin_snprintf (gimple_stmt_iterator *);
extern bool arith_code_with_undefined_signed_overflow (tree_code);
extern gimple_seq rewrite_to_defined_overflow (gimple *);
extern void replace_call_with_value (gimple_stmt_iterator *, tree);
+extern tree tree_vec_extract (gimple_stmt_iterator *, tree, tree, tree, tree);
/* gimple_build, functionally matching fold_buildN, outputs stmts
int the provided sequence, matching and simplifying them on-the-fly.
Supposed to replace force_gimple_operand (fold_buildN (...), ...). */
extern tree gimple_build (gimple_seq *, location_t,
diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index 909f790..1c9701d 100644
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -118,11 +118,11 @@ build_word_mode_vector_type (int nunits)
typedef tree (*elem_op_func) (gimple_stmt_iterator *,
tree, tree, tree, tree, tree, enum tree_code,
tree);
-static inline tree
+tree
tree_vec_extract (gimple_stmt_iterator *gsi, tree type,
tree t, tree bitsize, tree bitpos)
{
if (TREE_CODE (t) == SSA_NAME)
{
