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Re: combine BIT_FIELD_REF and VEC_PERM_EXPR
On Mon, 3 Sep 2012, Richard Guenther wrote:
Please do the early outs where you compute the arguments. Thus, right
after getting op0 in this case or right after computing n for the n != 1 check.
I think you need to verify that the type of 'op' is actually the element type
of op0. The BIT_FIELD_REF can happily access elements two and three
of { 1, 2, 3, 4 } as a long for example. See the BIT_FIELD_REF foldings
in fold-const.c.
On Mon, 3 Sep 2012, Richard Guenther wrote:
If you use fold_build3 you need to check that the result is in expected form
(a is_gimple_invariant or an SSA_NAME).
I first tried this:
+ if (TREE_CODE (tem) != SSA_NAME
+ && TREE_CODE (tem) != BIT_FIELD_REF
+ && !is_gimple_min_invariant (tem))
+ return false;
but then I thought that fold_stmt probably does the right thing (?) so I
switched to it.
Now that I look at this line, I wonder if I am missing some unshare_expr for
p and/or op1.
If either is a CONSTRUCTOR and its def stmt is not removed and it survives
into tem then yes ...
I added an unconditional unshare_expr. I guess it would be possible to
look at if the permutation is only used once and in that case maybe not
call unshare_expr (?) and call remove_prop_source_from_use at the end, but
it gets a bit complicated and I don't think it helps compared to waiting
for the next DCE pass.
Please also add handling of code == CONSTRUCTOR.
The cases I tried were already handled by fre1. I can add code for
constructor, but I'll need to look for a testcase first. Can that go to a
different patch?
Yes.
This is currently handled by FRE. The only testcase I have that reaches
forwprop is bit_field_ref (vec_perm_expr (constructor)) and will require
me to disable this patch so I can test that one...
New version of the patch (I really think I already regtested it, but I'll
do it again to be sure):
2012-09-08 Marc Glisse <marc.glisse@inria.fr>
gcc/
* tree-ssa-forwprop.c (simplify_bitfield): New function.
(ssa_forward_propagate_and_combine): Call it.
gcc/testsuite/
* gcc.dg/tree-ssa/forwprop-21.c: New testcase.
--
Marc Glisse
Index: tree-ssa-forwprop.c
===================================================================
--- tree-ssa-forwprop.c (revision 191089)
+++ tree-ssa-forwprop.c (working copy)
@@ -2567,20 +2567,92 @@ combine_conversions (gimple_stmt_iterato
gimple_assign_set_rhs_code (stmt, CONVERT_EXPR);
update_stmt (stmt);
return remove_prop_source_from_use (op0) ? 2 : 1;
}
}
}
return 0;
}
+/* Combine an element access with a shuffle. Returns true if there were
+ any changes made, else it returns false. */
+
+static bool
+simplify_bitfield (gimple_stmt_iterator *gsi)
+{
+ gimple stmt = gsi_stmt (*gsi);
+ gimple def_stmt;
+ tree op, op0, op1, op2;
+ tree elem_type;
+ unsigned idx, n, size;
+ enum tree_code code;
+
+ op = gimple_assign_rhs1 (stmt);
+ gcc_checking_assert (TREE_CODE (op) == BIT_FIELD_REF);
+
+ op0 = TREE_OPERAND (op, 0);
+ if (TREE_CODE (op0) != SSA_NAME
+ || TREE_CODE (TREE_TYPE (op0)) != VECTOR_TYPE)
+ return false;
+
+ elem_type = TREE_TYPE (TREE_TYPE (op0));
+ if (TREE_TYPE (op) != elem_type)
+ return false;
+
+ size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));
+ op1 = TREE_OPERAND (op, 1);
+ n = TREE_INT_CST_LOW (op1) / size;
+ if (n != 1)
+ return false;
+
+ def_stmt = SSA_NAME_DEF_STMT (op0);
+ if (!def_stmt || !is_gimple_assign (def_stmt)
+ || !can_propagate_from (def_stmt))
+ return false;
+
+ op2 = TREE_OPERAND (op, 2);
+ idx = TREE_INT_CST_LOW (op2) / size;
+
+ code = gimple_assign_rhs_code (def_stmt);
+
+ if (code == VEC_PERM_EXPR)
+ {
+ tree p, m, index, tem;
+ unsigned nelts;
+ m = gimple_assign_rhs3 (def_stmt);
+ if (TREE_CODE (m) != VECTOR_CST)
+ return false;
+ nelts = VECTOR_CST_NELTS (m);
+ idx = TREE_INT_CST_LOW (VECTOR_CST_ELT (m, idx));
+ idx %= 2 * nelts;
+ if (idx < nelts)
+ {
+ p = gimple_assign_rhs1 (def_stmt);
+ }
+ else
+ {
+ p = gimple_assign_rhs2 (def_stmt);
+ idx -= nelts;
+ }
+ index = build_int_cst (TREE_TYPE (TREE_TYPE (m)), idx * size);
+ tem = build3 (BIT_FIELD_REF, TREE_TYPE (op),
+ unshare_expr (p), op1, index);
+ gimple_assign_set_rhs1 (stmt, tem);
+ fold_stmt (gsi);
+ update_stmt (gsi_stmt (*gsi));
+ return true;
+ }
+
+ return false;
+}
+
/* Determine whether applying the 2 permutations (mask1 then mask2)
gives back one of the input. */
static int
is_combined_permutation_identity (tree mask1, tree mask2)
{
tree mask;
unsigned int nelts, i, j;
bool maybe_identity1 = true;
bool maybe_identity2 = true;
@@ -2825,20 +2897,22 @@ ssa_forward_propagate_and_combine (void)
cfg_changed = true;
changed = did_something != 0;
}
else if (code == VEC_PERM_EXPR)
{
int did_something = simplify_permutation (&gsi);
if (did_something == 2)
cfg_changed = true;
changed = did_something != 0;
}
+ else if (code == BIT_FIELD_REF)
+ changed = simplify_bitfield (&gsi);
break;
}
case GIMPLE_SWITCH:
changed = simplify_gimple_switch (stmt);
break;
case GIMPLE_COND:
{
int did_something;
Index: testsuite/gcc.dg/tree-ssa/forwprop-21.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/forwprop-21.c (revision 0)
+++ testsuite/gcc.dg/tree-ssa/forwprop-21.c (revision 0)
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized" } */
+typedef int v4si __attribute__ ((vector_size (4 * sizeof(int))));
+
+int
+test (v4si *x, v4si *y)
+{
+ v4si m = { 2, 3, 6, 5 };
+ v4si z = __builtin_shuffle (*x, *y, m);
+ return z[2];
+}
+/* { dg-final { scan-tree-dump-not "VEC_PERM_EXPR" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
Property changes on: testsuite/gcc.dg/tree-ssa/forwprop-21.c
___________________________________________________________________
Added: svn:eol-style
+ native
Added: svn:keywords
+ Author Date Id Revision URL