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8273139: C2: assert(f <= 1 && f >= 0) failed: Incorrect frequency

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Backport-of: 68b40ec28658a2dd829c77281b0025e16095c170
This commit is contained in:
Tobias Hartmann 2022-02-03 06:21:53 +00:00
parent 313932af0a
commit 34f2864680
1 changed files with 14 additions and 17 deletions
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31
src/hotspot/share/opto/loopPredicate.cpp
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@ -1024,13 +1024,15 @@ private:
GrowableArray<float> _freqs; // cache frequencies
PhaseIdealLoop* _phase;
void set_rounding(int mode) {
// fesetround is broken on windows
NOT_WINDOWS(fesetround(mode);)
}
void check_frequency(float f) {
NOT_WINDOWS(assert(f <= 1 && f >= 0, "Incorrect frequency");)
float check_and_truncate_frequency(float f) {
assert(f >= 0, "Incorrect frequency");
// We do not perform an exact (f <= 1) check
// this would be error prone with rounding of floats.
// Performing a check like (f <= 1+eps) would be of benefit,
// however, it is not evident how to determine such an eps,
// given that an arbitrary number of add/mul operations
// are performed on these frequencies.
return (f > 1) ? 1 : f;
}
public:
@ -1040,7 +1042,6 @@ public:
float to(Node* n) {
// post order walk on the CFG graph from n to _dom
set_rounding(FE_TOWARDZERO); // make sure rounding doesn't push frequency above 1
IdealLoopTree* loop = _phase->get_loop(_dom);
Node* c = n;
for (;;) {
@ -1067,14 +1068,12 @@ public:
inner_head = inner_loop->_head->as_Loop();
inner_head->verify_strip_mined(1);
}
set_rounding(FE_UPWARD); // make sure rounding doesn't push frequency above 1
float loop_exit_cnt = 0.0f;
for (uint i = 0; i < inner_loop->_body.size(); i++) {
Node *n = inner_loop->_body[i];
float c = inner_loop->compute_profile_trip_cnt_helper(n);
loop_exit_cnt += c;
}
set_rounding(FE_TOWARDZERO);
float cnt = -1;
if (n->in(0)->is_If()) {
IfNode* iff = n->in(0)->as_If();
@ -1094,9 +1093,9 @@ public:
cnt = p * jmp->_fcnt;
}
float this_exit_f = cnt > 0 ? cnt / loop_exit_cnt : 0;
check_frequency(this_exit_f);
this_exit_f = check_and_truncate_frequency(this_exit_f);
f = f * this_exit_f;
check_frequency(f);
f = check_and_truncate_frequency(f);
} else {
float p = -1;
if (n->in(0)->is_If()) {
@ -1109,7 +1108,7 @@ public:
p = n->in(0)->as_Jump()->_probs[n->as_JumpProj()->_con];
}
f = f * p;
check_frequency(f);
f = check_and_truncate_frequency(f);
}
_freqs.at_put_grow(n->_idx, (float)f, -1);
_stack.pop();
@ -1117,7 +1116,7 @@ public:
float prev_f = _freqs_stack.pop();
float new_f = f;
f = new_f + prev_f;
check_frequency(f);
f = check_and_truncate_frequency(f);
uint i = _stack.index();
if (i < n->req()) {
c = n->in(i);
@ -1130,9 +1129,7 @@ public:
}
}
if (_stack.size() == 0) {
set_rounding(FE_TONEAREST);
check_frequency(f);
return f;
return check_and_truncate_frequency(f);
}
} else if (c->is_Loop()) {
ShouldNotReachHere();