On 2/9/22 03:45, Richard Biener wrote:
> On Tue, Feb 8, 2022 at 9:58 PM Andrew MacLeod <amacleod@redhat.com> wrote:
>> On 2/8/22 03:32, Richard Biener wrote:
>>> On Tue, Feb 8, 2022 at 2:33 AM Andrew MacLeod via Gcc-patches
>>> <gcc-patches@gcc.gnu.org> wrote:
>>>> On 2/7/22 09:29, Andrew MacLeod wrote:
>>>>> I have a proposal for PR 104288.
>>>>>
>>>>> ALL patches (in sequence) bootstrap on their own and each cause no
>>>>> regressions.
>>>> I've been continuing to work with this towards the GCC13 solution for
>>>> statement side effects. And There is another possibility we could
>>>> pursue which is less intrusive
>>>>
>>>> I adapted the portions of patch 2/4 which process nonnull, but changes
>>>> it from being in the nonnull class to being in the cache.
>>>>
>>>> THe main difference is it continues to use a single bit, just changing
>>>> all uses of it to *always* mean its non-null on exit to the block.
>>>>
>>>> Range-on-entry is changed to only check dominator blocks, and
>>>> range_of_expr doesn't check the bit at all.. in both ranger and the cache.
>>>>
>>>> When we are doing the block walk and process side effects, the on-entry
>>>> *cache* range for the block is adjusted to be non-null instead. The
>>>> statements which precede this stmt have already been processed, and all
>>>> remaining statements in this block will now pick up this new non-value
>>>> from the on-entry cache. This should be perfectly safe.
>>>>
>>>> The final tweak is when range_of_expr is looking the def block, it
>>>> normally does not have an on entry cache value. (the def is in the
>>>> block, so there is no entry cache value). It now checks to see if we
>>>> have set one, which can only happen when we have been doing the
>>>> statement walk and set the on-entry cache with a non-null value. This
>>>> allows us to pick up the non-null range in the def block too... (once we
>>>> have passed a statement which set nonnull of course).
>>>>
>>>> THis patch provides much less change to trunk, and is probably a better
>>>> approach as its closer to what is going to happen in GCC13.
>>>>
>>>> Im still working with it, so the patch isnt fully refined yet... but it
>>>> bootstraps and passes all test with no regressions. And passes the new
>>>> tests too. I figured I would mention this before you look to hard at
>>>> the other patchset. the GCC11 patch doesn't change.
>>>>
>>>> Let me know if you prefer this.... I think I do :-) less churn, and
>>>> closer to end state.
>>> Yes, I very much prefer this - some comments to the other patches
>>> still apply to this one. Like using get_nonnull_args and probably
>>> adding a bail-out to computing ranges from stmts that can throw
>>> internally or have abnormal control flow (to not get into range-on-exit
>>> vs. normal vs. exceptional or abnormal edges).
>>>
>>> Richard.
>> with some minor performance tweaks, such as moving adjust_range() to the
>> header so it can be inlined .
>>
>> range-on-edge now applies the non-null from the src block if
>> appropriate, not in range-on-exit. That should resolve the internal
>> throwing statements I think. and I have switched over to
>> get_nonnull_args().
>>
>> Bootstraps on build-x86_64-pc-linux-gnu and passes all regressions.
>>
>> OK for trunk, or did I miss something?
> OK.
>
> I do think there's some confusion about -fnon-call-exceptions. The
> comment
>
> + // Non-call exceptions mean we could throw in the middle of the
> + // block, so just punt on those for now.
>
> also applies to regular exceptions, non-call vs. call EH just
> adds the possibility of non-call stmts to throw. I do not think that
> value-range propagation needs to care about stmts that throw
> in the middle of a block (which automatically means no EH edges
> and thus !stmt_can_throw_internal). When there are EH edges
> then restrictions apply to both calls and non-calls that throw.
>
> So whatever made those cfun->can_throw_non_call_exceptions
> necessary should have shown a more general issue with EH.
its probably paranoid carry over from a few years ago when getting off
the ground, combined with the non-null bit originally applying to the
entire block.
With these changes, and adjusting the outgoing values only on
non-abnormal/EH edge, I suspect they are no longer needed. I will look
at pulling them all out for the next release.
>
> That's something to look at, but not in the scope of this fix.
>
> Richard.
>
>> Andrew
>>
>> PS. odd.. I haven't seen the git diff be wrong before, but it shows the
>> ranger_cache::range_on_edge changes as being in
>> gimple_cache::range_of_expr... They are most definitely are not....
>> and it applies/de-applies fine.. so its just an oddity I guess.
>>
From 2f38b3de7958d83dab383c73029aedbd108d8930 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Mon, 7 Feb 2022 15:52:16 -0500
Subject: [PATCH] Register non-null side effects properly.
This patch adjusts uses of nonnull to accurately reflect "somewhere in block".
It also adds the ability to register statement side effects within a block
for ranger which will apply for the rest of the block.
PR tree-optimization/104288
gcc/
* gimple-range-cache.cc (non_null_ref::set_nonnull): New.
(non_null_ref::adjust_range): Move to header.
(ranger_cache::range_of_def): Don't check non-null.
(ranger_cache::entry_range): Don't check non-null.
(ranger_cache::range_on_edge): Check for nonnull on normal edges.
(ranger_cache::update_to_nonnull): New.
(non_null_loadstore): New.
(ranger_cache::block_apply_nonnull): New.
* ranger-cache.h (class non_null_ref): Update prototypes.
(non_null_ref::adjust_range): Move to here and inline.
(class ranger_cache): Update prototypes.
* gimple-range-path.cc (path_range_query::range_defined_in_block): Do
not search dominators.
(path_range_query::adjust_for_non_null_uses): Ditto.
* gimple-range.cc (gimple_ranger::range_of_expr): Check on-entry for
def overrides. Do not check nonnull.
(gimple_ranger::range_on_entry): Check dominators for nonnull.
(gimple_ranger::range_on_edge): Check for nonnull on normal edges..
* gimple-range.cc (gimple_ranger::register_side_effects): New.
* gimple-range.h (gimple_ranger::register_side_effects): New.
* tree-vrp.cc (rvrp_folder::fold_stmt): Call register_side_effects.
testsuite/gcc/
* gcc.dg/pr104288.c: New.
---
gcc/gimple-range-cache.cc | 135 ++++++++++++++++++++++++--------
gcc/gimple-range-cache.h | 31 ++++++++
gcc/gimple-range-path.cc | 4 +-
gcc/gimple-range.cc | 27 ++++++-
gcc/gimple-range.h | 1 +
gcc/testsuite/gcc.dg/pr104288.c | 23 ++++++
gcc/tree-vrp.cc | 8 +-
7 files changed, 187 insertions(+), 42 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr104288.c
@@ -29,6 +29,10 @@ along with GCC; see the file COPYING3. If not see
#include "gimple-pretty-print.h"
#include "gimple-range.h"
#include "tree-cfg.h"
+#include "target.h"
+#include "attribs.h"
+#include "gimple-iterator.h"
+#include "gimple-walk.h"
#define DEBUG_RANGE_CACHE (dump_file \
&& (param_ranger_debug & RANGER_DEBUG_CACHE))
@@ -50,6 +54,21 @@ non_null_ref::~non_null_ref ()
m_nn.release ();
}
+// This routine will update NAME in BB to be nonnull if it is not already.
+// return TRUE if the update happens.
+
+bool
+non_null_ref::set_nonnull (basic_block bb, tree name)
+{
+ gcc_checking_assert (gimple_range_ssa_p (name)
+ && POINTER_TYPE_P (TREE_TYPE (name)));
+ // Only process when its not already set.
+ if (non_null_deref_p (name, bb, false))
+ return false;
+ bitmap_set_bit (m_nn[SSA_NAME_VERSION (name)], bb->index);
+ return true;
+}
+
// Return true if NAME has a non-null dereference in block bb. If this is the
// first query for NAME, calculate the summary first.
// If SEARCH_DOM is true, the search the dominator tree as well.
@@ -87,35 +106,6 @@ non_null_ref::non_null_deref_p (tree name, basic_block bb, bool search_dom)
return false;
}
-// If NAME has a non-null dereference in block BB, adjust R with the
-// non-zero information from non_null_deref_p, and return TRUE. If
-// SEARCH_DOM is true, non_null_deref_p should search the dominator tree.
-
-bool
-non_null_ref::adjust_range (irange &r, tree name, basic_block bb,
- bool search_dom)
-{
- // Non-call exceptions mean we could throw in the middle of the
- // block, so just punt on those for now.
- if (cfun->can_throw_non_call_exceptions)
- return false;
-
- // We only care about the null / non-null property of pointers.
- if (!POINTER_TYPE_P (TREE_TYPE (name)))
- return false;
- if (r.undefined_p () || r.lower_bound () != 0 || r.upper_bound () == 0)
- return false;
- // Check if pointers have any non-null dereferences.
- if (non_null_deref_p (name, bb, search_dom))
- {
- // Remove zero from the range.
- unsigned prec = TYPE_PRECISION (TREE_TYPE (name));
- r.intersect (wi::one (prec), wi::max_value (prec, UNSIGNED));
- return true;
- }
- return false;
-}
-
// Allocate an populate the bitmap for NAME. An ON bit for a block
// index indicates there is a non-null reference in that block. In
// order to populate the bitmap, a quick run of all the immediate uses
@@ -1014,9 +1004,6 @@ ranger_cache::range_of_def (irange &r, tree name, basic_block bb)
else
r = gimple_range_global (name);
}
-
- if (bb)
- m_non_null.adjust_range (r, name, bb, false);
}
// Get the range of NAME as it occurs on entry to block BB.
@@ -1034,8 +1021,6 @@ ranger_cache::entry_range (irange &r, tree name, basic_block bb)
// Otherwise pick up the best available global value.
if (!m_on_entry.get_bb_range (r, name, bb))
range_of_def (r, name);
-
- m_non_null.adjust_range (r, name, bb, false);
}
// Get the range of NAME as it occurs on exit from block BB.
@@ -1089,6 +1074,9 @@ ranger_cache::range_of_expr (irange &r, tree name, gimple *stmt)
if (gimple_range_ssa_p (expr))
{
exit_range (r, expr, e->src);
+ // If this is not an abnormal edge, check for a non-null exit.
+ if ((e->flags & (EDGE_EH | EDGE_ABNORMAL)) == 0)
+ m_non_null.adjust_range (r, expr, e->src, false);
int_range_max edge_range;
if (m_gori.outgoing_edge_range_p (edge_range, e, expr, *this))
r.intersect (edge_range);
@@ -1467,3 +1455,82 @@ ranger_cache::range_from_dom (irange &r, tree name, basic_block bb)
}
return true;
}
+
+// This routine will update NAME in block BB to the nonnull state.
+// It will then update the on-entry cache for this block to be non-null
+// if it isn't already.
+
+void
+ranger_cache::update_to_nonnull (basic_block bb, tree name)
+{
+ tree type = TREE_TYPE (name);
+ if (gimple_range_ssa_p (name) && POINTER_TYPE_P (type))
+ {
+ m_non_null.set_nonnull (bb, name);
+ // Update the on-entry cache for BB to be non-zero. Note this can set
+ // the on entry value in the DEF block, which can override the def.
+ int_range_max r;
+ exit_range (r, name, bb);
+ if (r.varying_p ())
+ {
+ r.set_nonzero (type);
+ m_on_entry.set_bb_range (name, bb, r);
+ }
+ }
+}
+
+// Adapted from infer_nonnull_range_by_dereference and check_loadstore
+// to process nonnull ssa_name OP in S. DATA contains the ranger_cache.
+
+static bool
+non_null_loadstore (gimple *s, tree op, tree, void *data)
+{
+ if (TREE_CODE (op) == MEM_REF || TREE_CODE (op) == TARGET_MEM_REF)
+ {
+ /* Some address spaces may legitimately dereference zero. */
+ addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (op));
+ if (!targetm.addr_space.zero_address_valid (as))
+ {
+ tree ssa = TREE_OPERAND (op, 0);
+ basic_block bb = gimple_bb (s);
+ ((ranger_cache *)data)->update_to_nonnull (bb, ssa);
+ }
+ }
+ return false;
+}
+
+// This routine is used during a block walk to move the state of non-null for
+// any operands on stmt S to nonnull.
+
+void
+ranger_cache::block_apply_nonnull (gimple *s)
+{
+ if (!flag_delete_null_pointer_checks)
+ return;
+ if (is_a<gphi *> (s))
+ return;
+ if (gimple_code (s) == GIMPLE_ASM || gimple_clobber_p (s))
+ return;
+ if (is_a<gcall *> (s))
+ {
+ tree fntype = gimple_call_fntype (s);
+ bitmap nonnullargs = get_nonnull_args (fntype);
+ // Process any non-null arguments
+ if (nonnullargs)
+ {
+ basic_block bb = gimple_bb (s);
+ for (unsigned i = 0; i < gimple_call_num_args (s); i++)
+ {
+ if (bitmap_empty_p (nonnullargs) || bitmap_bit_p (nonnullargs, i))
+ {
+ tree op = gimple_call_arg (s, i);
+ update_to_nonnull (bb, op);
+ }
+ }
+ BITMAP_FREE (nonnullargs);
+ }
+ // Fallthru and walk load/store ops now.
+ }
+ walk_stmt_load_store_ops (s, (void *)this, non_null_loadstore,
+ non_null_loadstore);
+}
@@ -36,12 +36,41 @@ public:
bool non_null_deref_p (tree name, basic_block bb, bool search_dom = true);
bool adjust_range (irange &r, tree name, basic_block bb,
bool search_dom = true);
+ bool set_nonnull (basic_block bb, tree name);
private:
vec <bitmap> m_nn;
void process_name (tree name);
bitmap_obstack m_bitmaps;
};
+// If NAME has a non-null dereference in block BB, adjust R with the
+// non-zero information from non_null_deref_p, and return TRUE. If
+// SEARCH_DOM is true, non_null_deref_p should search the dominator tree.
+
+inline bool
+non_null_ref::adjust_range (irange &r, tree name, basic_block bb,
+ bool search_dom)
+{
+ // Non-call exceptions mean we could throw in the middle of the
+ // block, so just punt on those for now.
+ if (cfun->can_throw_non_call_exceptions)
+ return false;
+ // We only care about the null / non-null property of pointers.
+ if (!POINTER_TYPE_P (TREE_TYPE (name)))
+ return false;
+ if (r.undefined_p () || r.lower_bound () != 0 || r.upper_bound () == 0)
+ return false;
+ // Check if pointers have any non-null dereferences.
+ if (non_null_deref_p (name, bb, search_dom))
+ {
+ // Remove zero from the range.
+ unsigned prec = TYPE_PRECISION (TREE_TYPE (name));
+ r.intersect (wi::one (prec), wi::max_value (prec, UNSIGNED));
+ return true;
+ }
+ return false;
+}
+
// This class manages a vector of pointers to ssa_block ranges. It
// provides the basis for the "range on entry" cache for all
// SSA names.
@@ -106,6 +135,8 @@ public:
void propagate_updated_value (tree name, basic_block bb);
+ void block_apply_nonnull (gimple *s);
+ void update_to_nonnull (basic_block bb, tree name);
non_null_ref m_non_null;
gori_compute m_gori;
@@ -358,7 +358,7 @@ path_range_query::range_defined_in_block (irange &r, tree name, basic_block bb)
}
if (bb)
- m_non_null.adjust_range (r, name, bb);
+ m_non_null.adjust_range (r, name, bb, false);
if (DEBUG_SOLVER && (bb || !r.varying_p ()))
{
@@ -528,7 +528,7 @@ path_range_query::adjust_for_non_null_uses (basic_block bb)
else
r.set_varying (TREE_TYPE (name));
- if (m_non_null.adjust_range (r, name, bb))
+ if (m_non_null.adjust_range (r, name, bb, false))
set_cache (r, name);
}
}
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-scalar-evolution.h"
#include "gimple-range.h"
#include "gimple-fold.h"
+#include "gimple-walk.h"
gimple_ranger::gimple_ranger () :
non_executable_edge_flag (cfun),
@@ -117,8 +118,10 @@ gimple_ranger::range_of_expr (irange &r, tree expr, gimple *stmt)
// If name is defined in this block, try to get an range from S.
if (def_stmt && gimple_bb (def_stmt) == bb)
{
- range_of_stmt (r, def_stmt, expr);
- m_cache.m_non_null.adjust_range (r, expr, bb, true);
+ // Check for a definition override from a block walk.
+ if (!POINTER_TYPE_P (TREE_TYPE (expr))
+ || !m_cache.block_range (r, bb, expr, false))
+ range_of_stmt (r, def_stmt, expr);
}
// Otherwise OP comes from outside this block, use range on entry.
else
@@ -151,7 +154,12 @@ gimple_ranger::range_on_entry (irange &r, basic_block bb, tree name)
if (m_cache.block_range (entry_range, bb, name))
r.intersect (entry_range);
- m_cache.m_non_null.adjust_range (r, name, bb, true);
+ if (dom_info_available_p (CDI_DOMINATORS))
+ {
+ basic_block dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
+ if (dom_bb)
+ m_cache.m_non_null.adjust_range (r, name, dom_bb, true);
+ }
if (idx)
tracer.trailer (idx, "range_on_entry", true, name, r);
@@ -227,6 +235,9 @@ gimple_ranger::range_on_edge (irange &r, edge e, tree name)
else
{
range_on_exit (r, e->src, name);
+ // If this is not an abnormal edge, check for a non-null exit .
+ if ((e->flags & (EDGE_EH | EDGE_ABNORMAL)) == 0)
+ m_cache.m_non_null.adjust_range (r, name, e->src, false);
gcc_checking_assert (r.undefined_p ()
|| range_compatible_p (r.type(), TREE_TYPE (name)));
@@ -436,6 +447,16 @@ gimple_ranger::fold_stmt (gimple_stmt_iterator *gsi, tree (*valueize) (tree))
return ret;
}
+// Called during dominator walks to register any side effects that take effect
+// from this point forward. Current release is only for tracking non-null
+// within a block.
+
+void
+gimple_ranger::register_side_effects (gimple *s)
+{
+ m_cache.block_apply_nonnull (s);
+}
+
// This routine will export whatever global ranges are known to GCC
// SSA_RANGE_NAME_INFO and SSA_NAME_PTR_INFO fields.
@@ -60,6 +60,7 @@ public:
void dump_bb (FILE *f, basic_block bb);
auto_edge_flag non_executable_edge_flag;
bool fold_stmt (gimple_stmt_iterator *gsi, tree (*) (tree));
+ void register_side_effects (gimple *s);
protected:
bool fold_range_internal (irange &r, gimple *s, tree name);
void prefill_name (irange &r, tree name);
new file mode 100644
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp -fdelete-null-pointer-checks" } */
+/* { dg-skip-if "" { keeps_null_pointer_checks } } */
+
+void keep(int result) __attribute__((noipa));
+void keep(int result)
+{
+ if (result)
+ __builtin_exit(0);
+}
+
+void foo (void *p) __attribute__((nonnull(1)));
+
+void bar (void *p)
+{
+ keep (p == 0);
+ foo (p);
+ if (!p)
+ __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "evrp" } } */
+/* { dg-final { scan-tree-dump-times "== 0B;" 1 "evrp" } } */
@@ -4309,9 +4309,11 @@ public:
bool fold_stmt (gimple_stmt_iterator *gsi) OVERRIDE
{
- if (m_simplifier.simplify (gsi))
- return true;
- return m_ranger->fold_stmt (gsi, follow_single_use_edges);
+ bool ret = m_simplifier.simplify (gsi);
+ if (!ret)
+ ret = m_ranger->fold_stmt (gsi, follow_single_use_edges);
+ m_ranger->register_side_effects (gsi_stmt (*gsi));
+ return ret;
}
private:
--
2.17.2