RFR (S) 8217639: Minimal and Zero builds fail after JDK-8217519 (Improve RegMask population count calculation)
Aleksey Shipilev
shade at redhat.com
Wed Jan 23 16:50:00 UTC 2019
Bug:
https://bugs.openjdk.java.net/browse/JDK-8217639
Reason: New test references "extern uint8_t byte[] bitsInByte", and that is defined in
libadt/vectset.cpp, which is not compiled when C2 is disabled in Minimal and Zero VM builds. I was
first considering to enabled libadt build when C2 is disabled, but the more straight-forward fix
would be to give the test its own golden data to test against. This would also implicitly test for
accidental bugs in bitsInByte matrix in production code.
Fix:
diff -r c96f9aa1f3d8 -r 29037fc5194d test/hotspot/gtest/utilities/test_population_count.cpp
--- a/test/hotspot/gtest/utilities/test_population_count.cpp Wed Jan 23 13:16:16 2019 +0000
+++ b/test/hotspot/gtest/utilities/test_population_count.cpp Wed Jan 23 17:04:25 2019 +0100
@@ -29,18 +29,35 @@
#include "utilities/globalDefinitions.hpp"
#include "unittest.hpp"
+uint8_t test_popcnt_bitsInByte[BITS_IN_BYTE_ARRAY_SIZE] = {
+ 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
+ 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
+};
TEST(population_count, sparse) {
- extern uint8_t bitsInByte[BITS_IN_BYTE_ARRAY_SIZE];
// Step through the entire input range from a random starting point,
// verify population_count return values against the lookup table
// approach used historically
uint32_t step = 4711;
for (uint32_t value = os::random() % step; value < UINT_MAX - step; value += step) {
- uint32_t lookup = bitsInByte[(value >> 24) & 0xff] +
- bitsInByte[(value >> 16) & 0xff] +
- bitsInByte[(value >> 8) & 0xff] +
- bitsInByte[ value & 0xff];
+ uint32_t lookup = test_popcnt_bitsInByte[(value >> 24) & 0xff] +
+ test_popcnt_bitsInByte[(value >> 16) & 0xff] +
+ test_popcnt_bitsInByte[(value >> 8) & 0xff] +
+ test_popcnt_bitsInByte[ value & 0xff];
EXPECT_EQ(lookup, population_count(value))
<< "value = " << value;
Testing: Linux x86_64 {server,zero,minimal} build and gtest:population_count
-Aleksey
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