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6988308: assert((cnt > 0.0f) && (prob > 0.0f)) failed: Bad frequency assignment in if

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Make sure cnt doesn't become negative and integer overflow doesn't happen.

Reviewed-by: kvn, twisti
This commit is contained in:
Igor Veresov 2011-04-13 14:33:03 -07:00
parent 5001776189
commit aac4b1553e
1 changed files with 5 additions and 4 deletions
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9
hotspot/src/share/vm/opto/parse2.cpp
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@ -795,8 +795,9 @@ float Parse::dynamic_branch_prediction(float &cnt) {
taken = method()->scale_count(taken); taken = method()->scale_count(taken);
not_taken = method()->scale_count(not_taken); not_taken = method()->scale_count(not_taken);
// Give up if too few counts to be meaningful // Give up if too few (or too many, in which case the sum will overflow) counts to be meaningful.
if (taken + not_taken < 40) { // We also check that individual counters are positive first, overwise the sum can become positive.
if (taken < 0 || not_taken < 0 || taken + not_taken < 40) {
if (C->log() != NULL) { if (C->log() != NULL) {
C->log()->elem("branch target_bci='%d' taken='%d' not_taken='%d'", iter().get_dest(), taken, not_taken); C->log()->elem("branch target_bci='%d' taken='%d' not_taken='%d'", iter().get_dest(), taken, not_taken);
} }
@ -804,13 +805,13 @@ float Parse::dynamic_branch_prediction(float &cnt) {
} }
// Compute frequency that we arrive here // Compute frequency that we arrive here
int sum = taken + not_taken; float sum = taken + not_taken;
// Adjust, if this block is a cloned private block but the // Adjust, if this block is a cloned private block but the
// Jump counts are shared. Taken the private counts for // Jump counts are shared. Taken the private counts for
// just this path instead of the shared counts. // just this path instead of the shared counts.
if( block()->count() > 0 ) if( block()->count() > 0 )
sum = block()->count(); sum = block()->count();
cnt = (float)sum / (float)FreqCountInvocations; cnt = sum / FreqCountInvocations;
// Pin probability to sane limits // Pin probability to sane limits
float prob; float prob;