https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113255
--- Comment #11 from Richard Biener <rguenth at gcc dot gnu.org> ---
diff --git a/gcc/alias.cc b/gcc/alias.cc
index b2ec4806d22..0150dd699db 100644
--- a/gcc/alias.cc
+++ b/gcc/alias.cc
@@ -2272,6 +2272,8 @@ static bool
base_alias_check (rtx x, rtx x_base, rtx y, rtx y_base,
machine_mode x_mode, machine_mode y_mode)
{
+ return 1;
+
/* If the address itself has no known base see if a known equivalent
value has one. If either address still has no known base, nothing
is known about aliasing. */
(an experiment I did many years ago already) gives clean testresults
besides
+FAIL: gcc.dg/guality/pr41447-1.c -O2 -DPREVENT_OPTIMIZATION execution test
+FAIL: gcc.dg/guality/pr41447-1.c -O3 -g -DPREVENT_OPTIMIZATION execution
test
+FAIL: gcc.dg/guality/pr41447-1.c -Os -DPREVENT_OPTIMIZATION execution test
+FAIL: gcc.dg/guality/pr41447-1.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none -DPREVENT_OPTIMIZATION execution test
and only minor change in code generation:
text data bss dec hex filename
48374841 64824 1939512 50379177 300b9a9 ../obj2/gcc/cc1plus
48375065 64824 1939512 50379401 300ba89 gcc/cc1plus
where the larger binary is the patched one.
Assembly-wise there are scheduling changes, missed scheduling over spills.
Recovering this and similar cases should be as easy as marking spill
MEMs with a flag (in MEM_EXPR) for example, distinguishing (classes of)
stack memory from the rest. We should have this already (spill_slot_decl,
set_mem_attrs_for_spill), not sure why it doesn't look effective.
Improving test coverage for desired transforms would be nice as well.
