From dd9ca9d770a18ce4b16d867f49fef3293b483ff5 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 8 Apr 2020 14:04:35 +0200 Subject: rtl-optimization/93946 - fix TBAA for redundant store removal in CSE It turns out RTL CSE tries to remove redundant stores but fails to do the usual validity check what such a change is TBAA neutral to later loads. This now triggers with the PR93946 testcases on nios2. 2020-04-08 Richard Biener PR rtl-optimization/93946 * cse.c (cse_insn): Record the tabled expression in src_related. Verify a redundant store removal is valid. --- gcc/cse.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) (limited to 'gcc/cse.c') diff --git a/gcc/cse.c b/gcc/cse.c index 3e8724b..f07bbdb 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -5074,7 +5074,7 @@ cse_insn (rtx_insn *insn) to prefer it. Copy it to src_related. The code below will then give it a negative cost. */ if (GET_CODE (dest) == code && rtx_equal_p (p->exp, dest)) - src_related = dest; + src_related = p->exp; } /* Find the cheapest valid equivalent, trying all the available @@ -5332,7 +5332,16 @@ cse_insn (rtx_insn *insn) && rtx_equal_p (trial, dest) && !side_effects_p (dest) && (cfun->can_delete_dead_exceptions - || insn_nothrow_p (insn))) + || insn_nothrow_p (insn)) + /* We can only remove the later store if the earlier aliases + at least all accesses the later one. */ + && (!MEM_P (trial) + || ((MEM_ALIAS_SET (dest) == MEM_ALIAS_SET (trial) + || alias_set_subset_of (MEM_ALIAS_SET (dest), + MEM_ALIAS_SET (trial))) + && (!MEM_EXPR (trial) + || refs_same_for_tbaa_p (MEM_EXPR (trial), + MEM_EXPR (dest)))))) { SET_SRC (sets[i].rtl) = trial; noop_insn = true; -- cgit v1.1