From c223dc70b75caab21a074ea7ccb1ea02c89307dc Mon Sep 17 00:00:00 2001
From: mmitchel <mmitchel@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Tue, 12 Jun 2001 11:17:09 +0000
Subject: [PATCH] * expr.c (store_field): Don't set MEM_ALIAS_SET for a
field in a structure at a variable address.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@43256 138bc75d-0d04-0410-961f-82ee72b054a4
---
gcc/ChangeLog | 5 +++++
gcc/expr.c | 11 ++++++++++-
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 971b753876db..f3fff9f4ba0d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2001-06-12 Mark Mitchell <mark@codesourcery.com>
+
+ * expr.c (store_field): Don't set MEM_ALIAS_SET for a field
+ in a structure at a variable address.
+
2001-06-12 Joseph S. Myers <jsm28@cam.ac.uk>
* doc/gcov.texi: Use more logical markup.
diff --git a/gcc/expr.c b/gcc/expr.c
index a7b0ff4ff12a..966656886430 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -5327,7 +5327,16 @@ store_field (target, bitsize, bitpos, mode, exp, value_mode,
(bitpos
/ BITS_PER_UNIT))));
MEM_SET_IN_STRUCT_P (to_rtx, 1);
- MEM_ALIAS_SET (to_rtx) = alias_set;
+ /* If the address of the structure varies, then it might be on
+ the stack. And, stack slots may be shared across scopes.
+ So, two different structures, of different types, can end up
+ at the same location. We will give the structures alias set
+ zero; here we must be careful not to give non-zero alias sets
+ to their fields. */
+ if (!rtx_varies_p (addr, /*for_alias=*/0))
+ MEM_ALIAS_SET (to_rtx) = alias_set;
+ else
+ MEM_ALIAS_SET (to_rtx) = 0;
return store_expr (exp, to_rtx, value_mode != VOIDmode);
}
--
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