On Wed, Oct 21, 2015 at 6:46 AM, Bin Cheng <bin.ch...@arm.com> wrote:
> Hi,
> As analyzed in PR67921, I think the issue is caused by fold_binary_loc which
> folds:
> 4 - (sizetype) &c - (sizetype) ((int *) p1_8(D) + ((sizetype) a_23 * 24 +
> 4))
> into below form:
> ((sizetype) -((int *) p1_8(D) + ((sizetype) a_23 * 24 + 4)) - (sizetype)
> &c) + 4
>
> Look the minus sizetype expression is folded as negative pointer expression,
> which seems incorrect. Apart from this, The direct reason of this ICE is in
> CHREC because of an overlook. In general CHREC supports NEGATE_EXPR for
> CHREC, the only problem is it uses pointer type for CHREC_RIGHT, rather than
> sizetype, when building pointer type CHREC.
>
> This simple patch fixes the ICE issue. Bootstrap and test on x86 & x86_64.
>
> Is it OK?
Hmm, I think not - we shouldn't ever get pointer typed
multiplications. Did you track
down which is the bogus fold transform (I agree the result above is
bogus)? It's
probably related to STRIP_NOPS stripping sizetype conversions from pointers
so we might get split_tree to build such negate. Note that split_tree strips
(sign!) nops itself and thus should probably simply receive op0 and op1 instead
of arg0 and arg1.
I'm testing
@@ -9505,8 +9523,8 @@ fold_binary_loc (location_t loc,
then the result with variables. This increases the chances of
literals being recombined later and of generating relocatable
expressions for the sum of a constant and literal. */
- var0 = split_tree (arg0, code, &con0, &lit0, &minus_lit0, 0);
- var1 = split_tree (arg1, code, &con1, &lit1, &minus_lit1,
+ var0 = split_tree (op0, code, &con0, &lit0, &minus_lit0, 0);
+ var1 = split_tree (op1, code, &con1, &lit1, &minus_lit1,
code == MINUS_EXPR);
/* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
which fixes the testcase for me.
Richard.
> Note, I do think the associate logic in fold_binary_loc needs fix, but that
> should be another patch.
>
>
> 2015-10-20 Bin Cheng <bin.ch...@arm.com>
>
> PR tree-optimization/67921
> * tree-chrec.c (chrec_fold_multiply): Use sizetype for CHREC_RIGHT
> if
> type is pointer type.
>
> 2015-10-20 Bin Cheng <bin.ch...@arm.com>
>
> PR tree-optimization/67921
> * gcc.dg/ubsan/pr67921.c: New test.
