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Add resoning behind comparison to -0 and +0 #143

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Apr 14, 2022
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Add resoning behind comparison to -0 and +0 #143

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58 changes: 57 additions & 1 deletion openj9.test.daa/src/test.daa/net/openj9/test/PDMoveShifts/TestShiftsAndConvert.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*******************************************************************************
* Copyright (c) 2017, 2019 IBM Corp.
* Copyright (c) 2017, 2022 IBM Corp.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which accompanies this distribution
Expand Down Expand Up @@ -2519,6 +2519,14 @@ public void testShiftLeftInvalidPrecision()
@Test
public void testLeftOffsetOne()
{
/* Both expectedArray and expectedArray2 are needed because
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@VermaSh We do not need to quote PoPs here. I think if you elaborate on behavior difference from z14 and z15 here, it would be sufficient. (I think one of the updates you posted earlier on internal issue would be more suitable).

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I have replaced the quote with a summary explaining the behavior change.

* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down Expand Up @@ -3449,6 +3457,14 @@ public double shiftRight(double x, int shift, boolean round)
@Test
public void testShiftLeftUnitCases()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down Expand Up @@ -3554,6 +3570,14 @@ public void testShiftLeftUnitCases()
@Test
public void testShiftRightUnitCases()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down Expand Up @@ -4481,6 +4505,14 @@ public void testRightShiftTopNibbleGarbage()
@Test
public void testZeroShifts1()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down Expand Up @@ -4508,6 +4540,14 @@ public void testZeroShifts1()
@Test
public void testZeroShifts2()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand All @@ -4532,6 +4572,14 @@ public void testZeroShifts2()
@Test
public void testZeroShifts3()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down Expand Up @@ -4561,6 +4609,14 @@ public void testZeroShifts3()
@Test
public void testZeroShifts4()
{
/* Both expectedArray and expectedArray2 are needed because
* there was a behavioral change for VSRP instruction on z15
* and up. On z15 and up, if the result following the shift
* is 0, it is treated as positive. However, on prior
* hardware the 0 would retain the sign of the input packed
* decimal. For example: doing a left shift by 1 on 5D (-5)
* would result in 0D (-0) on z14; and 0C (+0) on z15 and above.
*/
byte[] inputArray = new byte[10];
byte[] outputArray = new byte[10];
byte[] expectedArray = new byte[10];
Expand Down