On 25 July 2011 13:57, Richard Guenther <richard.guent...@gmail.com> wrote: > On Mon, Jul 25, 2011 at 12:52 PM, Ira Rosen <ira.ro...@linaro.org> wrote: >> On 25 July 2011 12:39, Richard Guenther <richard.guent...@gmail.com> wrote: >>> On Mon, Jul 25, 2011 at 11:10 AM, Ulrich Weigand <uweig...@de.ibm.com> >>> wrote: >>>> Richard Guenther wrote: >>>>> On Sun, Jul 24, 2011 at 2:02 PM, Ira Rosen <ira.ro...@linaro.org> wrote: >>>>> > On 21 July 2011 15:19, Ira Rosen <ira.ro...@linaro.org> wrote: >>>>> >> I reproduced the failure. It occurs without Richard's >>>>> >> (http://gcc.gnu.org/ml/gcc-patches/2011-07/msg01022.html) and this >>>>> >> patches too. Obviously the vectorized loop is executed, but at the >>>>> >> moment I don't understand why. I'll have a better look on Sunday. >>>>> > >>>>> > Actually it doesn't choose the vectorized code. But the scalar version >>>>> > gets optimized in a harmful way for SPU, AFAIU. >>>>> > Here is the scalar loop after vrp2 >>>>> > >>>>> > <bb 8>: >>>>> > # ivtmp.42_50 = PHI <ivtmp.42_59(3), ivtmp.42_45(10)> >>>>> > D.4593_42 = (void *) ivtmp.53_32; >>>>> > D.4520_33 = MEM[base: D.4593_42, offset: 0B]; >>>>> > D.4521_34 = D.4520_33 + 1; >>>>> > MEM[symbol: a, index: ivtmp.42_50, offset: 0B] = D.4521_34; >>>>> > ivtmp.42_45 = ivtmp.42_50 + 4; >>>>> > if (ivtmp.42_45 != 16) >>>>> > goto <bb 10>; >>>>> > else >>>>> > goto <bb 5>; >>>>> > >>>>> > and the load is changed by dom2 to: >>>>> > >>>>> > <bb 4>: >>>>> > ... >>>>> > D.4520_33 = MEM[base: vect_pa.9_19, offset: 0B]; >>>>> > ... >>>>> > >>>>> > where vector(4) int * vect_pa.9; >>>>> > >>>>> > And the scalar loop has no rotate for that load: >>>>> >>>>> Hum. This smells like we are hiding sth from the tree optimizers? >>>> >>>> Well, the back-end assumes a pointer to vector type is always >>>> naturally aligned, and therefore the data it points to can be >>>> accessed via a simple load, with no extra rotate needed. >>> >>> I can't see any use of VECTOR_TYPE in config/spu/, and assuming >>> anything about alignment just because of the kind of the pointer >>> is bogus - the scalar code does a scalar read using that pointer. >>> So the backend better should look at the memory operation, not >>> at the pointer type. That said, I can't find any code that looks >>> suspicious in the spu backend. >>> >>>> It seems what happened here is that somehow, a pointer to int >>>> gets replaced by a pointer to vector, even though their alignment >>>> properties are different. >>> >>> No, they are not. They get replaced if they are value-equivalent >>> in which case they are also alignment-equivalent. But well, the >>> dump snippet wasn't complete and I don't feel like building a >>> SPU cross to verify myself. >> >> I am attaching the complete file. > > The issue seems to be that the IV in question, vect_pa.9_19, is > defined as > > vect_pa.9_19 = (vector(4) int *) ivtmp.53_32; > > but ivtmp.53_32 does not have a definition at all. >
I am sorry, it's my fault, resending the file. Sorry, Ira > Richard. > >> >> Thanks, >> Ira >> >> >> >>> >>>> This vector pointer must originate somehow in the vectorizer, >>>> however, since the original C source does not contain any >>>> vector types at all ... >>> >>> That's for sure true, it must be the initial pointer we then increment >>> in the vectorized loop. >>> >>> Richard. >>> >>>> Bye, >>>> Ulrich >>>> >>>> -- >>>> Dr. Ulrich Weigand >>>> GNU Toolchain for Linux on System z and Cell BE >>>> ulrich.weig...@de.ibm.com >>>> >>> >> >
my--pr49771.c.124t.dom2
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