When translate_clast is called for a scop, scalar definitions are optimized out
and hence any subsequent uses of those scalars, outside the scop, represents a
problem. Also as code is generated for a scop, basic blocks in the scop are
moved around such that the block which contains the definition of a scalar no
longer dominates the basic block outside the scop which contains a use of that
scalar.
Attached reduced testcase block-3.c (derived from cpu2006-401.bzip2-bzlib.c)
fails in gloog->verify_ssa->verify_use at below:
>>>
else if (bb != def_bb
&& !dominated_by_p (CDI_DOMINATORS, bb, def_bb))
{
error ("definition in block %i does not dominate use in block %i",
def_bb->index, bb->index);
err = true;
}
>>>
Before translate_clast is called, here is an excerpt from the function:
<bb 3>:
# SMT.48_24 = PHI <SMT.48_20(4), SMT.48_18(2)>
# i_28 = PHI <i_10(4), 0(2)>
# SMT.49_29 = PHI <SMT.49_21(4), SMT.49_19(2)>
# SMT.48_20 = VDEF <SMT.48_24>
# SMT.49_21 = VDEF <SMT.49_29>
s_5->inUse[i_28] = 0;
i_10 = i_28 + 1;
if (i_10 <= 255)
goto <bb 4>;
else
goto <bb 5>;
<bb 4>:
goto <bb 3>;
<bb 5>:
<bb 6>:
# VUSE <SMT.48_20, SMT.49_21>
D.1656_11 = s_5->blockNo;
D.1657_12 = D.1656_11 + 1;
# SMT.48_22 = VDEF <SMT.48_20>
# SMT.49_23 = VDEF <SMT.49_21>
s_5->blockNo = D.1657_12;
return;
At this point bb 3 which contains the VDEF for SMT.48_20 and SMT.49_21
dominates bb 6 which contains the VUSE for the same. The VDEF is associated
with s_5->blockNo and the VUSE with s_5->inUse[i_28].
After translate_clast is called, here is an excerpt from the function:
BZ2_bzCompressInit (struct bz_stream * strm, int blockSize100k, int verbosity,
int workFactor)
{
struct EState * D.1728;
int D.1725;
int D.1726;
int D.1727;
int graphiteIV.63;
int graphiteIV.62;
Int32 pretmp.52;
int D.1656;
int D.1657;
Int32 i;
struct EState * s;
void * D.1643;
void * D.1642;
void * (*<T494>) (void *, int, int) D.1641;
<bb 2>:
# VUSE <SMT.47_14(D), SMT.49_15(D)>
D.1641_2 = strm_1(D)->bzalloc;
# VUSE <SMT.47_14(D), SMT.49_15(D)>
D.1642_3 = strm_1(D)->opaque;
# SMT.47_17 = VDEF <SMT.47_14(D)>
# SMT.48_18 = VDEF <SMT.48_16(D)>
# SMT.49_19 = VDEF <SMT.49_15(D)>
D.1643_4 = D.1641_2 (D.1642_3, 304, 1);
s_5 = (struct EState *) D.1643_4;
<bb 7>:
# graphiteIV.62_13 = PHI <0(2), graphiteIV.62_6(8)>
graphiteIV.62_6 = graphiteIV.62_13 + 1;
if (graphiteIV.62_6 <= 3)
goto <bb 11>;
else
goto <bb 5>;
<bb 11>:
graphiteIV.63_9 = graphiteIV.62_13 * 64;
<bb 9>:
# graphiteIV.63_27 = PHI <graphiteIV.63_9(11), graphiteIV.63_25(10)>
# SMT.48_24 = PHI <>
# SMT.49_29 = PHI <>
graphiteIV.63_25 = graphiteIV.63_27 + 1;
D.1725_26 = graphiteIV.62_13 * 64;
D.1726_30 = D.1725_26 + 63;
D.1727_31 = MIN_EXPR <D.1726_30, 255>;
if (graphiteIV.63_25 <= D.1727_31)
goto <bb 3>;
else
goto <bb 8>;
<bb 10>:
goto <bb 9>;
<bb 8>:
goto <bb 7>;
<bb 3>:
Invalid sum of outgoing probabilities 0.0%
Invalid sum of incoming frequencies 25, should be 9900
D.1728_32 = (struct EState *) D.1643_4;
D.1728_32->inUse[graphiteIV.63_27] = 0;
goto <bb 10>;
<bb 4>:
Invalid sum of incoming frequencies 0, should be 9800
<bb 5>:
<bb 6>:
# VUSE <SMT.48_20, SMT.49_21>
D.1656_11 = s_5->blockNo;
D.1657_12 = D.1656_11 + 1;
# SMT.48_22 = VDEF <SMT.48_20>
# SMT.49_23 = VDEF <SMT.49_21>
s_5->blockNo = D.1657_12;
return;
}
During translate_clast the scop is transformed and the scalar VDEFS for
SMT.48_20, SMT.49_21 are removed by graphite. Also bb 3 no longer
dominates bb 6.
--
Summary: [graphite] basic block containing VDEF of a scalar does
not dominate basic block containing VUSE of the same
scalar
Product: gcc
Version: 4.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: hjagasia at gcc dot gnu dot org
ReportedBy: hjagasia at gcc dot gnu dot org
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37684
