This improves rewrite_to_defined_overflow slightly if we already
have an unsigned type. The only place where this seems to show up
is ifcombine. It removes one extra statement which gets added and
then later on removed.
OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
gcc/ChangeLog:
PR tree-optimization/111276
* gimple-fold.cc (rewrite_to_defined_overflow): Don't
add a new lhs if we already the unsigned type.
---
gcc/gimple-fold.cc | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index fd01810581a..2fcafeada37 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -8721,10 +8721,19 @@ rewrite_to_defined_overflow (gimple *stmt, bool
in_place /* = false */)
op = gimple_convert (&stmts, type, op);
gimple_set_op (stmt, i, op);
}
- gimple_assign_set_lhs (stmt, make_ssa_name (type, stmt));
+ bool needs_cast_back = false;
+ if (!useless_type_conversion_p (type, TREE_TYPE (lhs)))
+ {
+ gimple_assign_set_lhs (stmt, make_ssa_name (type, stmt));
+ needs_cast_back = true;
+ }
+
if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
gimple_assign_set_rhs_code (stmt, PLUS_EXPR);
- gimple_set_modified (stmt, true);
+
+ if (needs_cast_back || stmts)
+ gimple_set_modified (stmt, true);
+
if (in_place)
{
gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
@@ -8734,6 +8743,10 @@ rewrite_to_defined_overflow (gimple *stmt, bool in_place
/* = false */)
}
else
gimple_seq_add_stmt (&stmts, stmt);
+
+ if (!needs_cast_back)
+ return stmts;
+
gimple *cvt = gimple_build_assign (lhs, NOP_EXPR, gimple_assign_lhs (stmt));
if (in_place)
{
--
2.31.1
