Ilya Matveev
42c4391654
This patch takes into account a corner case available for loops
over a progression (see backend.native/tests/external/codegen/box/
ranges/forInUntil/forInUntilMinint.kt test):
for (i in 0 until Int.MIN_VALUE) { ... }
Here we cannot use subtraction to obtain a right bound of the loop
due to an overflow. Instead we consider any loop with MIN_VALUE in
it's right bound as empty loop. Such behaviour is similar to the one
of 'until' method.
So now the empty check for a loops with 'until' call:
for (i in first until bound) { ... }
is as follows:
val last = getProgressionLast(first, bound, step) // Only if step==1
if (first <= last && bound > <Int|Long|Char>.MIN_VALUE) {
do { ... } while(i != last)
}
Further improvements: We can generate a simpler IR for some simple
frequent cases (e.g. for until calls without steps) and eliminate
loops if we can prove that they are empty.
22 lines
1.1 KiB
Kotlin
22 lines
1.1 KiB
Kotlin
fun main(args: Array<String>) {
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for (i in Int.MAX_VALUE - 1 .. Int.MAX_VALUE) { print(i); print(' ') }; println()
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for (i in Int.MAX_VALUE - 1 until Int.MAX_VALUE) { print(i); print(' ') }; println()
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for (i in Int.MIN_VALUE + 1 downTo Int.MIN_VALUE) { print(i); print(' ') }; println()
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// Empty loops
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for (i in Byte.MIN_VALUE until Byte.MIN_VALUE) { print(i); print(' ') }
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for (i in Short.MIN_VALUE until Short.MIN_VALUE) { print(i); print(' ') }
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for (i in Int.MIN_VALUE until Int.MIN_VALUE) { print(i); print(' ') }
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for (i in Long.MIN_VALUE until Long.MIN_VALUE) { print(i); print(' ') }
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for (i in 0.toChar() until 0.toChar()) { print(i); print(' ') }
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for (i in 0 until Byte.MIN_VALUE) { print(i); print(' ') }
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for (i in 0 until Short.MIN_VALUE) { print(i); print(' ') }
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for (i in 0 until Int.MIN_VALUE) { print(i); print(' ') }
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for (i in 0 until Long.MIN_VALUE) { print(i); print(' ') }
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for (i in 'a' until 0.toChar()) { print(i); print(' ') }
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val M = Int.MAX_VALUE / 2
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for (i in M + 4..M + 10 step M) { print(i); print(' ') }; println()
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} |