[Bug tree-optimization/41499] New: missed optimization: Scalar evolution analysis prevents vectorization

[Bug tree-optimization/41499] New: missed optimization: Scalar evolution analysis prevents vectorization

[eres at il dot ibm dot com]

The hot loop in SPEC2000/179.art scanner.c (line 615) does not get vectorized
due to data ref analysis failure:

(The original loop contains invariant store which I manually extracted out of
the loop. Will try to generate a testcase.)

Taken from the vectorizer dump:

(instantiate_scev
  (instantiate_below = 252)
  (evolution_loop = 56)
  (chrec = {(double *) pretmp.1559_2569 + (long unsigned int) pretmp.1564_2574,
+, (long unsigned int) pretmp.1561_2571}_56)
  (res = {(double *) pretmp.1559_2569 + (long unsigned int) pretmp.1564_2574,
+, (long unsigned int) pretmp.1561_2571}_56))
        base_address:
        offset from base address:
        constant offset from base address:
        step:
        aligned to:
        base_object: *((double *) pretmp.1559_2569 + (long unsigned int)
(D.8586_1080 * 8))
(compute_affine_dependence
  (stmt_a =
D.8555_1089 = D.8600_1088->P;
)
  (stmt_b =
D.8548_1100 = *D.8549_1099;
)
)

scanner.c:615: note: get vectype with 2 units of type double
scanner.c:615: note: vectype: vector double
scanner.c:615: note: not vectorized: data ref analysis failed D.8548_1100 =
*D.8549_1099;

scanner.c:615: note: bad data references.(get_loop_exit_condition

Here are the flags that I used:

/data1/eres/mainline45/bbuild/bin/gcc    -m64 -DSPEC_CPU2000_LP64       
-mrecip -m64 -fpeel-loops -funroll-loops -ftree-loop-linear -ffast-math  -O3 
-maltivec -mvsx  -Wa,-mpower7 -Wa,-mvsx   -mcpu=power7 -fwhole-program
--combine -fipa-matrix-reorg -fdump-tree-vect-details     scanner.c   -lm  -o
art


-- 
           Summary: missed optimization: Scalar evolution analysis prevents
                    vectorization
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: eres at il dot ibm dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41499

[Bug tree-optimization/41499] Scalar evolution analysis prevents vectorization

[eres at il dot ibm dot com]

------- Comment #1 from eres at il dot ibm dot com  2009-09-29 12:14 -------
I was using trunk -r152153 and run on powerpc64.


-- 

eres at il dot ibm dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
            Summary|missed optimization: Scalar |Scalar evolution analysis
                   |evolution analysis prevents |prevents vectorization
                   |vectorization               |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41499