https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124454
--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I will finish this up tomorrow but the patch so far:
```
diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
index e884cb5a966..676985a7e53 100644
--- a/gcc/regcprop.cc
+++ b/gcc/regcprop.cc
@@ -36,6 +36,7 @@
#include "cfgrtl.h"
#include "target.h"
#include "function-abi.h"
+#include "cfgcleanup.h"
/* The following code does forward propagation of hard register copies.
The object is to eliminate as many dependencies as possible, so that
@@ -1443,6 +1444,7 @@ pass_cprop_hardreg::execute (function *fun)
auto_vec<int> *curr = &worklist1;
auto_vec<int> *next = &worklist2;
bool any_debug_changes = false;
+ bool anychanges = false;
/* We need accurate notes. Earlier passes such as if-conversion may
leave notes in an inconsistent state. */
@@ -1462,7 +1464,10 @@ pass_cprop_hardreg::execute (function *fun)
FOR_EACH_BB_FN (bb, fun)
{
if (cprop_hardreg_bb (bb, all_vd, visited))
- curr->safe_push (bb->index);
+ {
+ curr->safe_push (bb->index);
+ anychanges = true;
+ }
if (all_vd[bb->index].n_debug_insn_changes)
any_debug_changes = true;
}
@@ -1489,7 +1494,10 @@ pass_cprop_hardreg::execute (function *fun)
{
bb = BASIC_BLOCK_FOR_FN (fun, index);
if (cprop_hardreg_bb (bb, all_vd, visited))
- next->safe_push (bb->index);
+ {
+ next->safe_push (bb->index);
+ anychanges = true;
+ }
if (all_vd[bb->index].n_debug_insn_changes)
any_debug_changes = true;
}
@@ -1501,6 +1509,14 @@ pass_cprop_hardreg::execute (function *fun)
}
free (all_vd);
+
+ /* Copying prop the sp into an mem can cause what was
+ a trapping instruction into a non-trapping one so
+ cleanup after that. */
+ if (anychanges
+ && cfun->can_throw_non_call_exceptions
+ && purge_all_dead_edges ())
+ cleanup_cfg (0);
return 0;
}
```
And it does not have a very small compile time penalty (a load) if not using
-fnon-call-exceptions so it should be suitable for stage 4 even as
non-call-exceptions is not likely for most code.
