The following avoids repeatedly turning VALUE RTXen into
sth useful and re-applying a constant offset through get_addr
via DSE check_mem_read_rtx. Instead perform this once for
all stores to be visited in check_mem_read_rtx. This avoids
allocating 1.6GB of garbage PLUS RTXen on the PR80960
testcase, fixing the memory usage regression from old GCC.
Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
Thanks,
Richard.
2021-01-27 Richard Biener <rguent...@suse.de>
PR rtl-optimization/80960
* dse.c (check_mem_read_rtx): Call get_addr on the
offsetted address.
---
gcc/dse.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/dse.c b/gcc/dse.c
index c88587e7d94..da0df54a2dd 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -2219,6 +2219,11 @@ check_mem_read_rtx (rtx *loc, bb_info_t bb_info)
}
if (maybe_ne (offset, 0))
mem_addr = plus_constant (get_address_mode (mem), mem_addr, offset);
+ /* Avoid passing VALUE RTXen as mem_addr to canon_true_dependence
+ which will over and over re-create proper RTL and re-apply the
+ offset above. See PR80960 where we almost allocate 1.6GB of PLUS
+ RTXen that way. */
+ mem_addr = get_addr (mem_addr);
if (group_id >= 0)
{
--
2.26.2
