of course the patch would be handy...
On 10/13/23 09:23, Andrew MacLeod wrote:
Technically PR 111622 exposes a bug in GCC 13, but its been papered
over on trunk by this:
commit 9ea74d235c7e7816b996a17c61288f02ef767985
Author: Richard Biener <rguent...@suse.de>
Date: Thu Sep 14 09:31:23 2023 +0200
tree-optimization/111294 - better DCE after forwprop
This removes a lot of dead statements, but those statements were being
added to the list of partial equivalences and causing some serious
compile time issues.
Rangers cache loops through equivalences when its propagating on-entry
values, so if the partial equivalence list is very large, it can
consume a lot of time. Typically, partial equivalence lists are
small. In this case, a lot of dead stmts were not removed, so there
was no redundancy elimination and it was causing an issue. This
patch actually speeds things up a hair in the normal case too.
Bootstrapped on x86_64-pc-linux-gnu with no regressions. pushed.
Andrew
From 4eea3c1872a941089cafa105a11d8e40b1a55929 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacl...@redhat.com>
Date: Thu, 12 Oct 2023 17:06:36 -0400
Subject: [PATCH] Do not add partial equivalences with no uses.
PR tree-optimization/111622
* value-relation.cc (equiv_oracle::add_partial_equiv): Do not
register a partial equivalence if an operand has no uses.
---
gcc/value-relation.cc | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/gcc/value-relation.cc b/gcc/value-relation.cc
index 0326fe7cde6..c0f513a0eb1 100644
--- a/gcc/value-relation.cc
+++ b/gcc/value-relation.cc
@@ -392,6 +392,9 @@ equiv_oracle::add_partial_equiv (relation_kind r, tree op1, tree op2)
// In either case, if PE2 has an entry, we simply do nothing.
if (pe2.members)
return;
+ // If there are no uses of op2, do not register.
+ if (has_zero_uses (op2))
+ return;
// PE1 is the LHS and already has members, so everything in the set
// should be a slice of PE2 rather than PE1.
pe2.code = pe_min (r, pe1.code);
@@ -409,6 +412,9 @@ equiv_oracle::add_partial_equiv (relation_kind r, tree op1, tree op2)
}
if (pe2.members)
{
+ // If there are no uses of op1, do not register.
+ if (has_zero_uses (op1))
+ return;
pe1.ssa_base = pe2.ssa_base;
// If pe2 is a 16 bit value, but only an 8 bit copy, we can't be any
// more than an 8 bit equivalence here, so choose MIN value.
@@ -418,6 +424,9 @@ equiv_oracle::add_partial_equiv (relation_kind r, tree op1, tree op2)
}
else
{
+ // If there are no uses of either operand, do not register.
+ if (has_zero_uses (op1) || has_zero_uses (op2))
+ return;
// Neither name has an entry, simply create op1 as slice of op2.
pe2.code = bits_to_pe (TYPE_PRECISION (TREE_TYPE (op2)));
if (pe2.code == VREL_VARYING)
--
2.41.0
