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8330045: Enhance array handling

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Co-authored-by: Christian Hagedorn <chagedorn@openjdk.org>
Co-authored-by: Emanuel Peter <epeter@openjdk.org>
Co-authored-by: Francisco Ferrari Bihurriet <fferrari@redhat.com>
Co-authored-by: Martin Balao <mbalao@redhat.com>
Reviewed-by: rhalade, ahgross, thartmann, epeter, adinn, roland
This commit is contained in:
Christian Hagedorn 2024-10-15 15:28:47 +00:00 committed by Jaikiran Pai
parent fa83309e10
commit 5f6c85420a
2 changed files with 113 additions and 47 deletions
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101
src/hotspot/share/opto/subnode.cpp
View File

@ -1620,27 +1620,17 @@ Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
return new BoolNode( ncmp, _test.negate() );
}
// Change ((x & (m - 1)) u< m) into (m > 0)
// This is the off-by-one variant of ((x & m) u<= m)
if (cop == Op_CmpU &&
_test._test == BoolTest::lt &&
cmp1_op == Op_AndI) {
Node* l = cmp1->in(1);
Node* r = cmp1->in(2);
for (int repeat = 0; repeat < 2; repeat++) {
bool match = r->Opcode() == Op_AddI && r->in(2)->find_int_con(0) == -1 &&
r->in(1) == cmp2;
if (match) {
// arraylength known to be non-negative, so a (arraylength != 0) is sufficient,
// but to be compatible with the array range check pattern, use (arraylength u> 0)
Node* ncmp = cmp2->Opcode() == Op_LoadRange
? phase->transform(new CmpUNode(cmp2, phase->intcon(0)))
: phase->transform(new CmpINode(cmp2, phase->intcon(0)));
return new BoolNode(ncmp, BoolTest::gt);
} else {
// commute and try again
l = cmp1->in(2);
r = cmp1->in(1);
// Transform: "((x & (m - 1)) <u m)" or "(((m - 1) & x) <u m)" into "(m >u 0)"
// This is case [CMPU_MASK] which is further described at the method comment of BoolNode::Value_cmpu_and_mask().
if (cop == Op_CmpU && _test._test == BoolTest::lt && cmp1_op == Op_AndI) {
Node* m = cmp2; // RHS: m
for (int add_idx = 1; add_idx <= 2; add_idx++) { // LHS: "(m + (-1)) & x" or "x & (m + (-1))"?
Node* maybe_m_minus_1 = cmp1->in(add_idx);
if (maybe_m_minus_1->Opcode() == Op_AddI &&
maybe_m_minus_1->in(2)->find_int_con(0) == -1 &&
maybe_m_minus_1->in(1) == m) {
Node* m_cmpu_0 = phase->transform(new CmpUNode(m, phase->intcon(0)));
return new BoolNode(m_cmpu_0, BoolTest::gt);
}
}
}
@ -1806,9 +1796,57 @@ Node *BoolNode::Ideal(PhaseGVN *phase, bool can_reshape) {
// }
}
//------------------------------Value------------------------------------------
// Change ((x & m) u<= m) or ((m & x) u<= m) to always true
// Same with ((x & m) u< m+1) and ((m & x) u< m+1)
// We use the following Lemmas/insights for the following two transformations (1) and (2):
// x & y <=u y, for any x and y (Lemma 1, masking always results in a smaller unsigned number)
// y <u y + 1 is always true if y != -1 (Lemma 2, (uint)(-1 + 1) == (uint)(UINT_MAX + 1) which overflows)
// y <u 0 is always false for any y (Lemma 3, 0 == UINT_MIN and nothing can be smaller than that)
//
// (1a) Always: Change ((x & m) <=u m ) or ((m & x) <=u m ) to always true (true by Lemma 1)
// (1b) If m != -1: Change ((x & m) <u m + 1) or ((m & x) <u m + 1) to always true:
// x & m <=u m is always true // (Lemma 1)
// x & m <=u m <u m + 1 is always true // (Lemma 2: m <u m + 1, if m != -1)
//
// A counter example for (1b), if we allowed m == -1:
// (x & m) <u m + 1
// (x & -1) <u 0
// x <u 0
// which is false for any x (Lemma 3)
//
// (2) Change ((x & (m - 1)) <u m) or (((m - 1) & x) <u m) to (m >u 0)
// This is the off-by-one variant of the above.
//
// We now prove that this replacement is correct. This is the same as proving
// "m >u 0" if and only if "x & (m - 1) <u m", i.e. "m >u 0 <=> x & (m - 1) <u m"
//
// We use (Lemma 1) and (Lemma 3) from above.
//
// Case "x & (m - 1) <u m => m >u 0":
// We prove this by contradiction:
// Assume m <=u 0 which is equivalent to m == 0:
// and thus
// x & (m - 1) <u m = 0 // m == 0
// y <u 0 // y = x & (m - 1)
// by Lemma 3, this is always false, i.e. a contradiction to our assumption.
//
// Case "m >u 0 => x & (m - 1) <u m":
// x & (m - 1) <=u (m - 1) // (Lemma 1)
// x & (m - 1) <=u (m - 1) <u m // Using assumption m >u 0, no underflow of "m - 1"
//
//
// Note that the signed version of "m > 0":
// m > 0 <=> x & (m - 1) <u m
// does not hold:
// Assume m == -1 and x == -1:
// x & (m - 1) <u m
// -1 & -2 <u -1
// -2 <u -1
// UINT_MAX - 1 <u UINT_MAX // Signed to unsigned numbers
// which is true while
// m > 0
// is false which is a contradiction.
//
// (1a) and (1b) is covered by this method since we can directly return a true value as type while (2) is covered
// in BoolNode::Ideal since we create a new non-constant node (see [CMPU_MASK]).
const Type* BoolNode::Value_cmpu_and_mask(PhaseValues* phase) const {
Node* cmp = in(1);
if (cmp != nullptr && cmp->Opcode() == Op_CmpU) {
@ -1816,14 +1854,21 @@ const Type* BoolNode::Value_cmpu_and_mask(PhaseValues* phase) const {
Node* cmp2 = cmp->in(2);
if (cmp1->Opcode() == Op_AndI) {
Node* bound = nullptr;
Node* m = nullptr;
if (_test._test == BoolTest::le) {
bound = cmp2;
// (1a) "((x & m) <=u m)", cmp2 = m
m = cmp2;
} else if (_test._test == BoolTest::lt && cmp2->Opcode() == Op_AddI && cmp2->in(2)->find_int_con(0) == 1) {
bound = cmp2->in(1);
// (1b) "(x & m) <u m + 1" and "(m & x) <u m + 1", cmp2 = m + 1
Node* rhs_m = cmp2->in(1);
const TypeInt* rhs_m_type = phase->type(rhs_m)->isa_int();
if (rhs_m_type->_lo > -1 || rhs_m_type->_hi < -1) {
// Exclude any case where m == -1 is possible.
m = rhs_m;
}
}
if (cmp1->in(2) == bound || cmp1->in(1) == bound) {
if (cmp1->in(2) == m || cmp1->in(1) == m) {
return TypeInt::ONE;
}
}

59
test/hotspot/jtreg/compiler/c2/gvn/TestBoolNodeGVN.java
View File

@ -56,27 +56,47 @@ public class TestBoolNodeGVN {
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(failOn = IRNode.CMP_U,
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldReplaceCpmUCase2(int x, int m) {
return !(Integer.compareUnsigned((m & x), m) > 0);
}
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@Arguments(values = {Argument.DEFAULT, Argument.RANDOM_EACH})
@IR(failOn = IRNode.CMP_U,
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldReplaceCpmUCase3(int x, int m) {
m = Math.max(0, m);
return Integer.compareUnsigned((x & m), m + 1) < 0;
}
@Test
@Arguments(values = {Argument.DEFAULT, Argument.RANDOM_EACH})
@IR(failOn = IRNode.CMP_U,
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldReplaceCpmUCase4(int x, int m) {
m = Math.max(0, m);
return Integer.compareUnsigned((m & x), m + 1) < 0;
}
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(counts = {IRNode.CMP_U, "1"}, // m could be -1 and thus optimization cannot be applied
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldNotReplaceCpmUCase1(int x, int m) {
return Integer.compareUnsigned((x & m), m + 1) < 0;
}
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(failOn = IRNode.CMP_U,
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldReplaceCpmUCase4(int x, int m) {
@IR(counts = {IRNode.CMP_U, "1"}, // m could be -1 and thus optimization cannot be applied
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldNotReplaceCpmUCase2(int x, int m) {
return Integer.compareUnsigned((m & x), m + 1) < 0;
}
@ -92,8 +112,8 @@ public class TestBoolNodeGVN {
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(counts = {IRNode.CMP_U, "1"},
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldHaveCpmUCase2(int x, int m) {
return !(Integer.compareUnsigned((m & x), m - 1) > 0);
}
@ -101,8 +121,8 @@ public class TestBoolNodeGVN {
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(counts = {IRNode.CMP_U, "1"},
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldHaveCpmUCase3(int x, int m) {
return Integer.compareUnsigned((x & m), m + 2) < 0;
}
@ -110,22 +130,23 @@ public class TestBoolNodeGVN {
@Test
@Arguments(values = {Argument.DEFAULT, Argument.DEFAULT})
@IR(counts = {IRNode.CMP_U, "1"},
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
phase = CompilePhase.AFTER_PARSING,
applyIfPlatformOr = {"x64", "true", "aarch64", "true", "riscv64", "true"})
public static boolean testShouldHaveCpmUCase4(int x, int m) {
return Integer.compareUnsigned((m & x), m + 2) < 0;
}
private static void testCorrectness() {
int[] values = {
0, 1, 5, 8, 16, 42, 100, new Random().nextInt(0, Integer.MAX_VALUE), Integer.MAX_VALUE
-100, -42, -16, -8, -5, -1, 0, 1, 5, 8, 16, 42, 100,
new Random().nextInt(), Integer.MAX_VALUE, Integer.MIN_VALUE
};
for (int x : values) {
for (int m : values) {
if (!testShouldReplaceCpmUCase1(x, m) |
!testShouldReplaceCpmUCase2(x, m) |
!testShouldReplaceCpmUCase3(x, m) |
if (!testShouldReplaceCpmUCase1(x, m) ||
!testShouldReplaceCpmUCase2(x, m) ||
!testShouldReplaceCpmUCase3(x, m) ||
!testShouldReplaceCpmUCase4(x, m)) {
throw new RuntimeException("Bad result for x = " + x + " and m = " + m + ", expected always true");
}