On Thu, Apr 21, 2016 at 12:45 AM, Patrick Palka <patr...@parcs.ath.cx> wrote:
> During assert-location discovery, if an SSA name is live according to
> live_on_edge() on some outgoing edge E, then the SSA name definitely has
> at least two uses: the use on the outgoing edge, and the use in some BB
> dominating E->src from which the SSA_NAME and the potential assertion
> was discovered. These two uses can't be the same because the liveness
> array is populated on-the-fly in reverse postorder so the latter use
> which dominates BB couldn't have yet contributed to the liveness bitmap.
>
> So AFAICT it's not necessary to check live_on_edge() as well as
> !has_single_use() since the former check will imply the latter. So this
> patch removes these redundant calls to has_single_use() (and alse
> replaces the use of has_single_use() in find_assert_locations_1 with a
> liveness bitmap test which should be cheaper and more accurate).
>
> I bootstrapped and regtested this change on x86_64-pc-linux-gnu. I also
> confirmed that the number of calls made to register_new_assert_for
> before and after the patch remains the same during compilation of
> libstdc++ and during compilation of gimple-match.c and when running the
> tree-ssa.exp testsuite. Does this look OK to commit?
Ok.
Thanks,
Richard.
> gcc/ChangeLog:
>
> * tree-vrp.c (register_edge_assert_for_2): Remove redundant
> has_single_use() tests.
> (register_edge_assert_for_1): Likewise.
> (find_assert_locations_1): Check the liveness bitmap instead of
> calling has_single_use().
> ---
> gcc/tree-vrp.c | 29 ++++++++++-------------------
> 1 file changed, 10 insertions(+), 19 deletions(-)
>
> diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
> index bbdf9ce..3cb470b 100644
> --- a/gcc/tree-vrp.c
> +++ b/gcc/tree-vrp.c
> @@ -5145,8 +5145,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
>
> /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
> reachable from E. */
> - if (live_on_edge (e, name)
> - && !has_single_use (name))
> + if (live_on_edge (e, name))
> register_new_assert_for (name, name, comp_code, val, NULL, e, bsi);
>
> /* In the case of NAME <= CST and NAME being defined as
> @@ -5188,8 +5187,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> && (cst2 == NULL_TREE
> || TREE_CODE (cst2) == INTEGER_CST)
> && INTEGRAL_TYPE_P (TREE_TYPE (name3))
> - && live_on_edge (e, name3)
> - && !has_single_use (name3))
> + && live_on_edge (e, name3))
> {
> tree tmp;
>
> @@ -5215,8 +5213,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> && TREE_CODE (name2) == SSA_NAME
> && TREE_CODE (cst2) == INTEGER_CST
> && INTEGRAL_TYPE_P (TREE_TYPE (name2))
> - && live_on_edge (e, name2)
> - && !has_single_use (name2))
> + && live_on_edge (e, name2))
> {
> tree tmp;
>
> @@ -5319,8 +5316,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> tree op1 = gimple_assign_rhs2 (def_stmt);
> if (TREE_CODE (op0) == SSA_NAME
> && TREE_CODE (op1) == INTEGER_CST
> - && live_on_edge (e, op0)
> - && !has_single_use (op0))
> + && live_on_edge (e, op0))
> {
> enum tree_code reverse_op = (rhs_code == PLUS_EXPR
> ? MINUS_EXPR : PLUS_EXPR);
> @@ -5346,8 +5342,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> && (comp_code == LE_EXPR || comp_code == GT_EXPR
> || !tree_int_cst_equal (val,
> TYPE_MIN_VALUE (TREE_TYPE (val))))
> - && live_on_edge (e, name2)
> - && !has_single_use (name2))
> + && live_on_edge (e, name2))
> {
> tree tmp, cst;
> enum tree_code new_comp_code = comp_code;
> @@ -5392,8 +5387,7 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> && INTEGRAL_TYPE_P (TREE_TYPE (name2))
> && IN_RANGE (tree_to_uhwi (cst2), 1, prec - 1)
> && prec == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (val)))
> - && live_on_edge (e, name2)
> - && !has_single_use (name2))
> + && live_on_edge (e, name2))
> {
> mask = wi::mask (tree_to_uhwi (cst2), false, prec);
> val2 = fold_binary (LSHIFT_EXPR, TREE_TYPE (val), val, cst2);
> @@ -5498,12 +5492,10 @@ register_edge_assert_for_2 (tree name, edge e,
> gimple_stmt_iterator bsi,
> || !INTEGRAL_TYPE_P (TREE_TYPE (names[1]))
> || (TYPE_PRECISION (TREE_TYPE (name2))
> != TYPE_PRECISION (TREE_TYPE (names[1])))
> - || !live_on_edge (e, names[1])
> - || has_single_use (names[1]))
> + || !live_on_edge (e, names[1]))
> names[1] = NULL_TREE;
> }
> - if (live_on_edge (e, name2)
> - && !has_single_use (name2))
> + if (live_on_edge (e, name2))
> names[0] = name2;
> }
> }
> @@ -5724,8 +5716,7 @@ register_edge_assert_for_1 (tree op, enum tree_code
> code,
>
> /* We know that OP will have a zero or nonzero value. If OP is used
> more than once go ahead and register an assert for OP. */
> - if (live_on_edge (e, op)
> - && !has_single_use (op))
> + if (live_on_edge (e, op))
> {
> val = build_int_cst (TREE_TYPE (op), 0);
> register_new_assert_for (op, op, code, val, NULL, e, bsi);
> @@ -6158,7 +6149,7 @@ find_assert_locations_1 (basic_block bb, sbitmap live)
> /* Note we want to register the assert for the
> operand of the NOP_EXPR after SI, not after the
> conversion. */
> - if (! has_single_use (t))
> + if (bitmap_bit_p (live, SSA_NAME_VERSION (t)))
> register_new_assert_for (t, t, comp_code, value,
> bb, NULL, si);
> }
> --
> 2.8.1.231.g95ac767
>
