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Fix H.J. Lu's alpha-linux aliasing bug.

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* alias.c (true_dependence): Address with AND can alias scalars.
	(anti_dependence, output_dependence): Likewise.

From-SVN: r15063
This commit is contained in:
Jim Wilson 1997-09-03 19:28:49 +00:00 • committed by Jim Wilson
parent 03e7070558
commit fa8b602464
2 changed files with 13 additions and 2 deletions
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3
gcc/ChangeLog
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@ -1,5 +1,8 @@
Wed Sep 3 10:39:42 1997 Jim Wilson <wilson@cygnus.com>
* alias.c (true_dependence): Address with AND can alias scalars.
(anti_dependence, output_dependence): Likewise.
* alias.c (true_dependence): Test x for BLKmode, in addition to mem.
Wed Sep 3 09:28:50 CDT 1997 Joel Sherrill (joel@OARcorp.com)

12
gcc/alias.c
View file

@ -751,11 +751,14 @@ memrefs_conflict_p (xsize, x, ysize, y, c)
changed. A volatile and non-volatile reference can be interchanged
though.
A MEM_IN_STRUCT reference at a non-QImode varying address can never
A MEM_IN_STRUCT reference at a non-QImode non-AND varying address can never
conflict with a non-MEM_IN_STRUCT reference at a fixed address. We must
allow QImode aliasing because the ANSI C standard allows character
pointers to alias anything. We are assuming that characters are
always QImode here. */
always QImode here. We also must allow AND addresses, because they may
generate accesses outside the object being referenced. This is used to
generate aligned addresses from unaligned addresses, for instance, the
alpha storeqi_unaligned pattern. */
/* Read dependence: X is read after read in MEM takes place. There can
only be a dependence here if both reads are volatile. */
@ -816,6 +819,7 @@ true_dependence (mem, mem_mode, x, varies)
if (MEM_IN_STRUCT_P (x) == MEM_IN_STRUCT_P (mem)
|| mem_mode == QImode || mem_mode == BLKmode
|| GET_MODE (x) == QImode || GET_MODE (x) == BLKmode
|| GET_CODE (x_addr) == AND || GET_CODE (mem_addr) == AND
|| varies (x_addr) == varies (mem_addr))
return 1;
@ -856,9 +860,11 @@ anti_dependence (mem, x)
SIZE_FOR_MODE (x), XEXP (x, 0), 0)
&& ! (MEM_IN_STRUCT_P (mem) && rtx_addr_varies_p (mem)
&& GET_MODE (mem) != QImode
&& GET_CODE (XEXP (mem, 0)) != AND
&& ! MEM_IN_STRUCT_P (x) && ! rtx_addr_varies_p (x))
&& ! (MEM_IN_STRUCT_P (x) && rtx_addr_varies_p (x)
&& GET_MODE (x) != QImode
&& GET_CODE (XEXP (x, 0)) != AND
&& ! MEM_IN_STRUCT_P (mem) && ! rtx_addr_varies_p (mem)));
}
@ -881,9 +887,11 @@ output_dependence (mem, x)
SIZE_FOR_MODE (x), XEXP (x, 0), 0)
&& ! (MEM_IN_STRUCT_P (mem) && rtx_addr_varies_p (mem)
&& GET_MODE (mem) != QImode
&& GET_CODE (XEXP (mem, 0)) != AND
&& ! MEM_IN_STRUCT_P (x) && ! rtx_addr_varies_p (x))
&& ! (MEM_IN_STRUCT_P (x) && rtx_addr_varies_p (x)
&& GET_MODE (x) != QImode
&& GET_CODE (XEXP (x, 0)) != AND
&& ! MEM_IN_STRUCT_P (mem) && ! rtx_addr_varies_p (mem)));
}