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tree-ssa-alias.c (nonaliasing_component_refs_p): Rename into...

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* tree-ssa-alias.c (nonaliasing_component_refs_p): Rename into...
	(aliasing_component_refs_p): ...this.  Return true if there is no
	common base and the base access types have the same alias set.
	(indirect_ref_may_alias_decl_p): Adjust for above renaming.
	(indirect_refs_may_alias_p): Likewise.

From-SVN: r153523
This commit is contained in:
Eric Botcazou 2009-10-24 10:05:23 +00:00 committed by Eric Botcazou
parent 26d8af3556
commit 72580319c2
4 changed files with 59 additions and 15 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2009-10-24 Eric Botcazou <ebotcazou@adacore.com>
* tree-ssa-alias.c (nonaliasing_component_refs_p): Rename into...
(aliasing_component_refs_p): ...this. Return true if there is no
common base and the base access types have the same alias set.
(indirect_ref_may_alias_decl_p): Adjust for above renaming.
(indirect_refs_may_alias_p): Likewise.
2009-10-23 Joseph Myers <joseph@codesourcery.com>
PR c/40033

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2009-10-24 Eric Botcazou <ebotcazou@adacore.com>
* gnat.dg/opt4.adb: New test.
2009-10-23 Joseph Myers <joseph@codesourcery.com>
PR c/40033

22
gcc/testsuite/gnat.dg/opt4.adb Normal file
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@ -0,0 +1,22 @@
-- { dg-do run }
-- { dg-options "-O2" }
procedure Opt4 is
type Rec (D : Natural) is record
S : String (1..D);
end record;
procedure Test (R : Rec) is
begin
if R.D /= 9 then
raise Program_Error;
end if;
end;
R : Rec(9);
begin
R := (9, "123456789");
Test (R);
end;

40
gcc/tree-ssa-alias.c
View File

@ -553,10 +553,10 @@ same_type_for_tbaa (tree type1, tree type2)
on an indirect reference may alias. */
static bool
nonaliasing_component_refs_p (tree ref1, tree type1,
HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
tree ref2, tree type2,
HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
aliasing_component_refs_p (tree ref1, tree type1,
HOST_WIDE_INT offset1, HOST_WIDE_INT max_size1,
tree ref2, tree type2,
HOST_WIDE_INT offset2, HOST_WIDE_INT max_size2)
{
/* If one reference is a component references through pointers try to find a
common base and apply offset based disambiguation. This handles
@ -600,9 +600,19 @@ nonaliasing_component_refs_p (tree ref1, tree type1,
offset1 -= offadj;
return ranges_overlap_p (offset1, max_size1, offset2, max_size2);
}
/* If we have two type access paths B1.path1 and B2.path2 they may
only alias if either B1 is in B2.path2 or B2 is in B1.path1. */
return false;
/* We haven't found any common base to apply offset-based disambiguation.
There are two cases:
1. The base access types have the same alias set. This can happen
in Ada when a function with an unconstrained parameter passed by
reference is called on a constrained object and inlined: the types
have the same alias set but aren't equivalent. The references may
alias in this case.
2. The base access types don't have the same alias set, i.e. one set
is a subset of the other. We have proved that B1 is not in the
access path B2.path and that B2 is not in the access path B1.path
so the references may not alias. */
return get_alias_set (type1) == get_alias_set (type2);
}
/* Return true if two memory references based on the variables BASE1
@ -681,10 +691,10 @@ indirect_ref_may_alias_decl_p (tree ref1, tree ptr1,
if (ref1 && ref2
&& handled_component_p (ref1)
&& handled_component_p (ref2))
return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
offset1, max_size1,
ref2, TREE_TYPE (base2),
offset2, max_size2);
return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
offset1, max_size1,
ref2, TREE_TYPE (base2),
offset2, max_size2);
return true;
}
@ -742,10 +752,10 @@ indirect_refs_may_alias_p (tree ref1, tree ptr1,
if (ref1 && ref2
&& handled_component_p (ref1)
&& handled_component_p (ref2))
return nonaliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
offset1, max_size1,
ref2, TREE_TYPE (TREE_TYPE (ptr2)),
offset2, max_size2);
return aliasing_component_refs_p (ref1, TREE_TYPE (TREE_TYPE (ptr1)),
offset1, max_size1,
ref2, TREE_TYPE (TREE_TYPE (ptr2)),
offset2, max_size2);
return true;
}