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re PR ada/43096 (miscompilation of ACATS c37105a at -O2) 

PR ada/43096
	* tree-ssa-alias.c (same_type_for_tbaa): Return -1 if the types have
	the same alias set.

From-SVN: r157102
This commit is contained in:
Eric Botcazou 2010-02-26 23:10:24 +00:00 committed by Eric Botcazou
parent 4d16c0dc91
commit 2743db69c5
2 changed files with 15 additions and 7 deletions
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gcc/ChangeLog
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@ -1,3 +1,9 @@
2010-02-26 Eric Botcazou <ebotcazou@adacore.com>
PR ada/43096
* tree-ssa-alias.c (same_type_for_tbaa): Return -1 if the types have
the same alias set.
2010-02-26 H.J. Lu <hongjiu.lu@intel.com> 2010-02-26 H.J. Lu <hongjiu.lu@intel.com>
* config.gcc: Set the default arch at least to Prescott for * config.gcc: Set the default arch at least to Prescott for

16
gcc/tree-ssa-alias.c
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@ -544,13 +544,15 @@ same_type_for_tbaa (tree type1, tree type2)
&& TREE_CODE (type2) == ARRAY_TYPE) && TREE_CODE (type2) == ARRAY_TYPE)
return -1; return -1;
/* In Ada, an lvalue of unconstrained type can be used to access an object /* ??? In Ada, an lvalue of an unconstrained type can be used to access an
of one of its constrained subtypes, for example when a function with an object of one of its constrained subtypes, e.g. when a function with an
unconstrained parameter passed by reference is called on a constrained unconstrained parameter passed by reference is called on an object and
object and inlined. In this case, the types have the same alias set. */ inlined. But, even in the case of a fixed size, type and subtypes are
if (TYPE_SIZE (type1) && TYPE_SIZE (type2) not equivalent enough as to share the same TYPE_CANONICAL, since this
&& TREE_CONSTANT (TYPE_SIZE (type1)) != TREE_CONSTANT (TYPE_SIZE (type2)) would mean that conversions between them are useless, whereas they are
&& get_alias_set (type1) == get_alias_set (type2)) not (e.g. type and subtypes can have different modes). So, in the end,
they are only guaranteed to have the same alias set. */
if (get_alias_set (type1) == get_alias_set (type2))
return -1; return -1;
/* The types are known to be not equal. */ /* The types are known to be not equal. */