gcc/ChangeLog:
* gimple-fold.cc (optimize_atomic_compare_exchange_p): enable
for SCALAR_FLOAT_TYPE_P type of expected var, or if TYPE_PRECISION
is different from mode's bitsize
(fold_builtin_atomic_compare_exchange): if TYPE_PRECISION is
different from mode's bitsize, try to keep track all the bits and
mix it with VIEW_CONVERT_EXPR<itype>(expected).
Signed-off-by: xndcn <xnd...@gmail.com>
---
gcc/gimple-fold.cc | 77 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 71 insertions(+), 6 deletions(-)
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index cb4b57250..321ff4f41 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -5306,12 +5306,7 @@ optimize_atomic_compare_exchange_p (gimple *stmt)
|| !auto_var_in_fn_p (TREE_OPERAND (expected, 0), current_function_decl)
|| TREE_THIS_VOLATILE (etype)
|| VECTOR_TYPE_P (etype)
- || TREE_CODE (etype) == COMPLEX_TYPE
- /* Don't optimize floating point expected vars, VIEW_CONVERT_EXPRs
- might not preserve all the bits. See PR71716. */
- || SCALAR_FLOAT_TYPE_P (etype)
- || maybe_ne (TYPE_PRECISION (etype),
- GET_MODE_BITSIZE (TYPE_MODE (etype))))
+ || TREE_CODE (etype) == COMPLEX_TYPE)
return false;
tree weak = gimple_call_arg (stmt, 3);
@@ -5350,8 +5345,10 @@ fold_builtin_atomic_compare_exchange
(gimple_stmt_iterator *gsi)
tree itype = TREE_VALUE (TREE_CHAIN (TREE_CHAIN (parmt)));
tree ctype = build_complex_type (itype);
tree expected = TREE_OPERAND (gimple_call_arg (stmt, 1), 0);
+ tree etype = TREE_TYPE (expected);
bool throws = false;
edge e = NULL;
+ tree allbits = NULL_TREE;
gimple *g = gimple_build_assign (make_ssa_name (TREE_TYPE (expected)),
expected);
gsi_insert_before (gsi, g, GSI_SAME_STMT);
@@ -5362,6 +5359,67 @@ fold_builtin_atomic_compare_exchange
(gimple_stmt_iterator *gsi)
build1 (VIEW_CONVERT_EXPR, itype,
gimple_assign_lhs (g)));
gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+ // VIEW_CONVERT_EXPRs might not preserve all the bits. See PR71716.
+ // so we have to keep track all bits here.
+ if (maybe_ne (TYPE_PRECISION (etype),
+ GET_MODE_BITSIZE (TYPE_MODE (etype))))
+ {
+ gimple_stmt_iterator cgsi
+ = gsi_after_labels (single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+ allbits = create_tmp_var (itype);
+ // allbits is initialized to 0, which can be ignored first time
+ gimple *init_stmt
+ = gimple_build_assign (allbits, build_int_cst (itype, 0));
+ gsi_insert_before (&cgsi, init_stmt, GSI_SAME_STMT);
+ tree maskbits = create_tmp_var (itype);
+ // maskbits is initialized to full 1 (0xFFF...)
+ init_stmt = gimple_build_assign (maskbits, build1 (BIT_NOT_EXPR,
+ itype, allbits));
+ gsi_insert_before (&cgsi, init_stmt, GSI_SAME_STMT);
+
+ // g = g & maskbits
+ g = gimple_build_assign (make_ssa_name (itype),
+ build2 (BIT_AND_EXPR, itype,
+ gimple_assign_lhs (g), maskbits));
+ gsi_insert_before (gsi, g, GSI_SAME_STMT);
+
+ gimple *def_mask = gimple_build_assign (
+ make_ssa_name (itype),
+ build2 (LSHIFT_EXPR, itype, build_int_cst (itype, 1),
+ build_int_cst (itype, TYPE_PRECISION (etype))));
+ gsi_insert_before (gsi, def_mask, GSI_SAME_STMT);
+ def_mask = gimple_build_assign (make_ssa_name (itype),
+ build2 (MINUS_EXPR, itype,
+ gimple_assign_lhs (def_mask),
+ build_int_cst (itype, 1)));
+ gsi_insert_before (gsi, def_mask, GSI_SAME_STMT);
+ // maskbits = (1 << TYPE_PRECISION (etype)) - 1
+ def_mask = gimple_build_assign (maskbits, SSA_NAME,
+ gimple_assign_lhs (def_mask));
+ gsi_insert_before (gsi, def_mask, GSI_SAME_STMT);
+
+ // paddingbits = (~maskbits) & allbits
+ def_mask
+ = gimple_build_assign (make_ssa_name (itype),
+ build1 (BIT_NOT_EXPR, itype,
+ gimple_assign_lhs (def_mask)));
+ gsi_insert_before (gsi, def_mask, GSI_SAME_STMT);
+ def_mask
+ = gimple_build_assign (make_ssa_name (itype),
+ build2 (BIT_AND_EXPR, itype, allbits,
+ gimple_assign_lhs (def_mask)));
+ gsi_insert_before (gsi, def_mask, GSI_SAME_STMT);
+
+ // g = g | paddingbits, i.e.,
+ // g = (VIEW_CONVERT_EXPR<itype>(expected) & maskbits)
+ // | (allbits &(~maskbits))
+ g = gimple_build_assign (make_ssa_name (itype),
+ build2 (BIT_IOR_EXPR, itype,
+ gimple_assign_lhs (g),
+ gimple_assign_lhs (def_mask)));
+ gsi_insert_before (gsi, g, GSI_SAME_STMT);
+ }
}
int flag = (integer_onep (gimple_call_arg (stmt, 3)) ? 256 : 0)
+ int_size_in_bytes (itype);
@@ -5410,6 +5468,13 @@ fold_builtin_atomic_compare_exchange
(gimple_stmt_iterator *gsi)
gsi_insert_after (gsi, g, GSI_NEW_STMT);
if (!useless_type_conversion_p (TREE_TYPE (expected), itype))
{
+ // save all bits here
+ if (maybe_ne (TYPE_PRECISION (etype),
+ GET_MODE_BITSIZE (TYPE_MODE (etype))))
+ {
+ g = gimple_build_assign (allbits, SSA_NAME, gimple_assign_lhs (g));
+ gsi_insert_after (gsi, g, GSI_NEW_STMT);
+ }
g = gimple_build_assign (make_ssa_name (TREE_TYPE (expected)),
VIEW_CONVERT_EXPR,
build1 (VIEW_CONVERT_EXPR, TREE_TYPE (expected),
--
2.25.1
