Hi!
We pattern recognize already many different patterns, and closest to the
requested one also
yc = (type) y;
zc = (type) z;
x = yc + zc;
w = (typeof_y) x;
if (x > max)
where y/z has the same unsigned type and type is a wider unsigned type
and max is maximum value of the narrower unsigned type.
But apparently people are creative in writing this in diffent ways,
this requests
yc = (type) y;
zc = (type) z;
x = yc + zc;
w = (typeof_y) x;
if (x >> narrower_type_bits)
The following patch implements that.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-05-13 Jakub Jelinek <ja...@redhat.com>
PR middle-end/113982
* tree-ssa-math-opts.cc (arith_overflow_check_p): Also return 1
for RSHIFT_EXPR by precision of maxval if shift result is only
used in a cast or comparison against zero.
(match_arith_overflow): Handle the RSHIFT_EXPR use case.
* gcc.dg/pr113982.c: New test.
--- gcc/tree-ssa-math-opts.cc.jj 2024-04-11 09:26:36.318369218 +0200
+++ gcc/tree-ssa-math-opts.cc 2024-05-10 18:17:08.795744811 +0200
@@ -3947,6 +3947,66 @@ arith_overflow_check_p (gimple *stmt, gi
else
return 0;
+ if (maxval
+ && ccode == RSHIFT_EXPR
+ && crhs1 == lhs
+ && TREE_CODE (crhs2) == INTEGER_CST
+ && wi::to_widest (crhs2) == TYPE_PRECISION (TREE_TYPE (maxval)))
+ {
+ tree shiftlhs = gimple_assign_lhs (use_stmt);
+ if (!shiftlhs)
+ return 0;
+ use_operand_p use;
+ if (!single_imm_use (shiftlhs, &use, &cur_use_stmt))
+ return 0;
+ if (gimple_code (cur_use_stmt) == GIMPLE_COND)
+ {
+ ccode = gimple_cond_code (cur_use_stmt);
+ crhs1 = gimple_cond_lhs (cur_use_stmt);
+ crhs2 = gimple_cond_rhs (cur_use_stmt);
+ }
+ else if (is_gimple_assign (cur_use_stmt))
+ {
+ if (gimple_assign_rhs_class (cur_use_stmt) == GIMPLE_BINARY_RHS)
+ {
+ ccode = gimple_assign_rhs_code (cur_use_stmt);
+ crhs1 = gimple_assign_rhs1 (cur_use_stmt);
+ crhs2 = gimple_assign_rhs2 (cur_use_stmt);
+ }
+ else if (gimple_assign_rhs_code (cur_use_stmt) == COND_EXPR)
+ {
+ tree cond = gimple_assign_rhs1 (cur_use_stmt);
+ if (COMPARISON_CLASS_P (cond))
+ {
+ ccode = TREE_CODE (cond);
+ crhs1 = TREE_OPERAND (cond, 0);
+ crhs2 = TREE_OPERAND (cond, 1);
+ }
+ else
+ return 0;
+ }
+ else
+ {
+ enum tree_code sc = gimple_assign_rhs_code (cur_use_stmt);
+ tree castlhs = gimple_assign_lhs (cur_use_stmt);
+ if (!CONVERT_EXPR_CODE_P (sc)
+ || !castlhs
+ || !INTEGRAL_TYPE_P (TREE_TYPE (castlhs))
+ || (TYPE_PRECISION (TREE_TYPE (castlhs))
+ > TYPE_PRECISION (TREE_TYPE (maxval))))
+ return 0;
+ return 1;
+ }
+ }
+ else
+ return 0;
+ if ((ccode != EQ_EXPR && ccode != NE_EXPR)
+ || crhs1 != shiftlhs
+ || !integer_zerop (crhs2))
+ return 0;
+ return 1;
+ }
+
if (TREE_CODE_CLASS (ccode) != tcc_comparison)
return 0;
@@ -4049,6 +4109,7 @@ arith_overflow_check_p (gimple *stmt, gi
_8 = IMAGPART_EXPR <_7>;
if (_8)
and replace (utype) x with _9.
+ Or with x >> popcount (max) instead of x > max.
Also recognize:
x = ~z;
@@ -4481,10 +4542,62 @@ match_arith_overflow (gimple_stmt_iterat
gcc_checking_assert (is_gimple_assign (use_stmt));
if (gimple_assign_rhs_class (use_stmt) == GIMPLE_BINARY_RHS)
{
- gimple_assign_set_rhs1 (use_stmt, ovf);
- gimple_assign_set_rhs2 (use_stmt, build_int_cst (type, 0));
- gimple_assign_set_rhs_code (use_stmt,
- ovf_use == 1 ? NE_EXPR : EQ_EXPR);
+ if (gimple_assign_rhs_code (use_stmt) == RSHIFT_EXPR)
+ {
+ g2 = gimple_build_assign (make_ssa_name (boolean_type_node),
+ ovf_use == 1 ? NE_EXPR : EQ_EXPR,
+ ovf, build_int_cst (type, 0));
+ gimple_stmt_iterator gsiu = gsi_for_stmt (use_stmt);
+ gsi_insert_before (&gsiu, g2, GSI_SAME_STMT);
+ gimple_assign_set_rhs_with_ops (&gsiu, NOP_EXPR,
+ gimple_assign_lhs (g2));
+ update_stmt (use_stmt);
+ use_operand_p use;
+ single_imm_use (gimple_assign_lhs (use_stmt), &use,
+ &use_stmt);
+ if (gimple_code (use_stmt) == GIMPLE_COND)
+ {
+ gcond *cond_stmt = as_a <gcond *> (use_stmt);
+ gimple_cond_set_lhs (cond_stmt, ovf);
+ gimple_cond_set_rhs (cond_stmt, build_int_cst (type, 0));
+ }
+ else
+ {
+ gcc_checking_assert (is_gimple_assign (use_stmt));
+ if (gimple_assign_rhs_class (use_stmt)
+ == GIMPLE_BINARY_RHS)
+ {
+ gimple_assign_set_rhs1 (use_stmt, ovf);
+ gimple_assign_set_rhs2 (use_stmt,
+ build_int_cst (type, 0));
+ }
+ else if (gimple_assign_cast_p (use_stmt))
+ gimple_assign_set_rhs1 (use_stmt, ovf);
+ else
+ {
+ tree_code sc = gimple_assign_rhs_code (use_stmt);
+ gcc_checking_assert (sc == COND_EXPR);
+ tree cond = gimple_assign_rhs1 (use_stmt);
+ cond = build2 (TREE_CODE (cond),
+ boolean_type_node, ovf,
+ build_int_cst (type, 0));
+ gimple_assign_set_rhs1 (use_stmt, cond);
+ }
+ }
+ update_stmt (use_stmt);
+ gsi_remove (&gsiu, true);
+ gsiu = gsi_for_stmt (g2);
+ gsi_remove (&gsiu, true);
+ continue;
+ }
+ else
+ {
+ gimple_assign_set_rhs1 (use_stmt, ovf);
+ gimple_assign_set_rhs2 (use_stmt, build_int_cst (type, 0));
+ gimple_assign_set_rhs_code (use_stmt,
+ ovf_use == 1
+ ? NE_EXPR : EQ_EXPR);
+ }
}
else
{
--- gcc/testsuite/gcc.dg/pr113982.c.jj 2024-05-10 15:00:28.536651833 +0200
+++ gcc/testsuite/gcc.dg/pr113982.c 2024-05-10 15:01:49.721570343 +0200
@@ -0,0 +1,60 @@
+/* PR middle-end/113982 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-widening_mul" } */
+
+#if __SIZEOF_INT128__
+typedef __uint128_t W;
+typedef unsigned long long T;
+#else
+typedef unsigned long long W;
+typedef unsigned int T;
+#endif
+#define B __CHAR_BIT__ * sizeof (T)
+
+struct S { int p; T r; };
+
+struct S
+foo (T x, T y)
+{
+ W z = (W) x + y;
+ return (struct S) { z >> B, (T) z };
+}
+
+struct S
+bar (T x)
+{
+ W z = (W) x + 132;
+ return (struct S) { z >> B, (T) z };
+}
+
+struct S
+baz (T x, unsigned short y)
+{
+ W z = (W) x + y;
+ return (struct S) { z >> B, (T) z };
+}
+
+struct S
+qux (unsigned short x, T y)
+{
+ W z = (W) x + y;
+ return (struct S) { z >> B, (T) z };
+}
+
+struct S
+corge (T x, T y)
+{
+ T w = x + y;
+ W z = (W) x + y;
+ return (struct S) { z >> B, w };
+}
+
+struct S
+garple (T x, T y)
+{
+ W z = (W) x + y;
+ T w = x + y;
+ return (struct S) { z >> B, w };
+}
+
+/* { dg-final { scan-tree-dump-times "ADD_OVERFLOW" 6 "widening_mul" { target
{ i?86-*-* x86_64-*-* } } } } */
Jakub
