[PATCH]aarch64: falkor-tag-collision-avoidance.c fix valid_src_p for use of uninitialized value

[Andrea Corallo]

Hi all,

Testing the backport of pr94530 fix (af19e4d0e23e) to GCC 9 I realized
this is not entirely correct.

aarch64_classify_address sets the base field of struct
aarch64_address_info for all aarch64_address_type with the exception
of ADDRESS_SYMBOLIC.  In this case we would access an uninitialized
value.  The attached patch fixes the issue.

Bootstraped on aarch64 and regressioned.  Okay for trunk?

I've also tested af19e4d0e23e + the current patch rebased on on top of
the gcc-9 branch.  Okay to backport?

Andrea

PS I'm wondering if would be good also to always set the addr field in
aarch64_classify_address for safeness.

gcc/ChangeLog

2020-??-??  Andrea Corallo  <andrea.cora...@arm.com>

        * config/aarch64/falkor-tag-collision-avoidance.c
        (valid_src_p): Check for aarch64_address_info type before
        accessing base field.

>From 4af5bb32cd88bb4e65591207839fb0e276b2eb23 Mon Sep 17 00:00:00 2001
From: Andrea Corallo <andrea.cora...@arm.com>
Date: Thu, 9 Apr 2020 15:34:50 +0100
Subject: [PATCH] pr94530 2

---
 gcc/config/aarch64/falkor-tag-collision-avoidance.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/config/aarch64/falkor-tag-collision-avoidance.c b/gcc/config/aarch64/falkor-tag-collision-avoidance.c
index f850153fae02..fb56ff66bfab 100644
--- a/gcc/config/aarch64/falkor-tag-collision-avoidance.c
+++ b/gcc/config/aarch64/falkor-tag-collision-avoidance.c
@@ -538,7 +538,7 @@ valid_src_p (rtx src, rtx_insn *insn, struct loop *loop, bool *pre_post,
   if (!aarch64_classify_address (&addr, XEXP (x, 0), mode, true))
     return false;
 
-  if (!REG_P (addr.base))
+  if (addr.type == ADDRESS_SYMBOLIC || !REG_P (addr.base))
     return false;
 
   unsigned regno = REGNO (addr.base);
-- 
2.17.1