42 lines
2.0 KiB
JavaScript
42 lines
2.0 KiB
JavaScript
description(
|
|
"This tests that a constant folding on a node that has obviously mispredicted type doesn't send the compiler into an infinite loop."
|
|
);
|
|
|
|
// A function with an argument correctly predicted double.
|
|
function foo(x) {
|
|
// Two variables holding constants such that the bytecode generation constant folder
|
|
// will not constant fold the division below, but the DFG constant folder will.
|
|
var a = 1;
|
|
var b = 4000;
|
|
// A division that is going to be predicted integer on the first compilation. The
|
|
// compilation will be triggered from the loop below so the slow case counter of the
|
|
// division will be 1, which is too low for the division to be predicted double.
|
|
// If we constant fold this division, we'll have a constant node that is predicted
|
|
// integer but that contains a double. The subsequent addition to x, which is
|
|
// predicted double, will lead the Fixup phase to inject an Int32ToDouble node on
|
|
// the constant-that-was-a-division; subsequent fases in the fixpoint will constant
|
|
// fold that Int32ToDouble. And hence we will have an infinite loop. The correct fix
|
|
// is to disable constant folding of mispredicted nodes; that allows the normal
|
|
// process of correcting predictions (OSR exit profiling, exiting to profiled code,
|
|
// and recompilation with exponential backoff) to take effect so that the next
|
|
// compilation does not make this same mistake.
|
|
var c = (a / b) + x;
|
|
// A pointless loop to force the first compilation to occur before the division got
|
|
// hot. If this loop was not here then the division would be known to produce doubles
|
|
// on the first compilation.
|
|
var d = 0;
|
|
for (var i = 0; i < 1000; ++i)
|
|
d++;
|
|
return c + d;
|
|
}
|
|
|
|
silentTestPass = true;
|
|
noInline(foo);
|
|
|
|
// Call foo() enough times to make it optimize three times.
|
|
// NOTE: We no longer recompile this three times.
|
|
for (var i = 0; i < 2; i = dfgIncrement({f:foo, i:i + 1, n:1}))
|
|
shouldBe("foo(0.5)", "1000.50025");
|
|
|
|
|