'make test' in examples/ssymm fails: 'tiled' output differs

[bondhugula]

make[1]: Entering directory '/home/uday/git/pluto/examples/ssymm'
touch .test
./orig 2> out_orig
12.579868s
./tiled 2> out_tiled
3.264796s
diff -q out_orig out_tiled
Files out_orig and out_tiled differ
make[1]: *** [../common.mk:106: test] Error 1

[bondhugula]

This is the transformation found for 'tiled'.

../../polycc ssymm.c --noparallel --codegen-context=100 -o ssymm.tiled.c
[pluto] compute_deps (isl)
[pluto] Number of statements: 3
[pluto] Total number of loops: 8
[pluto] Number of deps: 15
[pluto] Maximum domain dimensionality: 3
[pluto] Number of parameters: 1
[pluto] Diamond tiling not possible/useful
[pluto] Affine transformations [<iter coeff's> ]

T(S1): (2, i, k, j)
loop types (scalar, loop, loop, loop)

T(S2): (0, i, j, k)
loop types (scalar, loop, loop, loop)

T(S3): (1, i, j, 0)
loop types (scalar, loop, loop, scalar)

[Pluto] After tiling:
T(S1): (2, i/32, k/32, j/32, i, k, j)
loop types (scalar, loop, loop, loop, loop, loop, loop)

T(S2): (0, i/32, j/32, k/32, i, j, k)
loop types (scalar, loop, loop, loop, loop, loop, loop)

T(S3): (1, i/32, j/32, i, j, 0, 0)
loop types (scalar, loop, loop, loop, loop, scalar, scalar)

[Pluto] After intra-tile optimize
T(S1): (2, i/32, k/32, j/32, i, j, k)
loop types (scalar, loop, loop, loop, loop, loop, loop)

T(S2): (0, i/32, j/32, k/32, i, j, k)
loop types (scalar, loop, loop, loop, loop, loop, loop)

T(S3): (1, i/32, j/32, i, j, 0, 0)
loop types (scalar, loop, loop, loop, loop, scalar, scalar)

[pluto] using statement-wise -fs/-ls options: S1(5,7), S2(5,7), S3(4,7),
[Pluto] Output written to ssymm.tiled.c

[pluto] Timing statistics
[pluto] SCoP extraction + dependence analysis time: 0.001345s
[pluto] Auto-transformation time: 0.022889s
[pluto] Total constraint solving time (LP/MIP/ILP) time: 0.002466s
[pluto] Code generation time: 0.041953s
[pluto] Other/Misc time: 0.224972s
[pluto] Total time: 0.291159s
[pluto] All times: 0.001345 0.022889 0.041953 0.224972
gcc -O3 -march=native -mtune=native -ftree-vectorize -DTIME ssymm.tiled.c -o tiled -lm

[bondhugula]

The output of 'par' and 'tiled' match, but they both differ from that of 'orig'.

[bondhugula]

This is a precision related issue likely associated with value unsafe optimizations. The error goes away with -O1. And even at -O3, the difference is for a small number of values and at the sixth decimal place.