On 5/29/24 03:19, Richard Biener wrote:
On Tue, May 28, 2024 at 8:57 PM Andrew MacLeod<amacl...@redhat.com> wrote:
The original patch causing the PR made ranger's cache re-entrant to
enable SCEV to use the current range_query when called from within ranger..
SCEV uses the currently active range query (via get_range_query()) for
picking up values. fold_using_range is the general purpose stmt folder
many components use, and it takes a range_query to use for folding.
When propagating values in the cache, we need to ensure no new queries
are invoked, and when the cache is propagating and calculating outgoing
edges, it switches to a read only range_query which uses what it knows
about global values to come up with best result using current state.
SCEV is unaware of what the caller is using for a range_query, so when
attempting to fold a PHI node, it is re-invoking the current query
during propagation which is undesired behavior. This patch tells
fold_using_range to not use SCEV if the range_query being used is not
the same as the one SCEV is going to use.
Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
Can we dump a hint to an active dump-file if this happens? I suppose it's
an unwanted situation, like the pass not setting the active ranger? Sth
like
if (src.query () != get_range_query (cfun)
&& dump_file)
fprintf (dump_file, "Using a range query different from the
installed one\n");
(or better wording).
Btw, could we install src.query () as the global range query around the
relevant recursion or is the place around where we'd need to do this
not so clear-cut?
As requested, this patch will issues a message in the listing if we fail
to execute SCEV under normal usage.
Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.
Andrew
From 3c4b0b16bcbc731e65ab8b2cf58429e24756728a Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacl...@redhat.com>
Date: Thu, 30 May 2024 09:40:46 -0400
Subject: [PATCH 1/2] scev query mismatch message
Add a message to the listing if SCEV is not invoked because of a
range_query mismatch
* gimple-range-fold.cc (range_of_ssa_name_with_loop_info): Issue a
message if SCEV is not invoked due to a mismatch.
---
gcc/gimple-range-fold.cc | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/gcc/gimple-range-fold.cc b/gcc/gimple-range-fold.cc
index 98a4877ba18..6037c29ce11 100644
--- a/gcc/gimple-range-fold.cc
+++ b/gcc/gimple-range-fold.cc
@@ -1267,9 +1267,18 @@ fold_using_range::range_of_ssa_name_with_loop_info (vrange &r, tree name,
// SCEV currently invokes get_range_query () for values. If the query
// being passed in is not the same SCEV will use, do not invoke SCEV.
// This can be remove if/when SCEV uses a passed in range-query.
- if (src.query () != get_range_query (cfun)
- || !range_of_var_in_loop (r, name, l, phi, src.query ()))
- r.set_varying (TREE_TYPE (name));
+ if (src.query () != get_range_query (cfun))
+ {
+ r.set_varying (TREE_TYPE (name));
+ // Report the msmatch if SRC is not the global query. The cache
+ // uses a global query and would provide numerous false positives.
+ if (dump_file && (dump_flags & TDF_DETAILS)
+ && src.query () != get_global_range_query ())
+ fprintf (dump_file,
+ "fold_using-range:: SCEV not invoked due to mismatched queries\n");
+ }
+ else if (!range_of_var_in_loop (r, name, l, phi, src.query ()))
+ r.set_varying (TREE_TYPE (name));
}
// -----------------------------------------------------------------------
--
2.45.0
