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8303238: Create generalizations for existing LShift ideal transforms #12734

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8303238: Create generalizations for existing LShift ideal transforms #12734

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a1baa1d
Create generalizations for existing LShift ideal transforms
jaskarth Feb 23, 2023
bd16156
Comments from code review
jaskarth Mar 7, 2023
9a6ff3c
Update comments in IR tests
jaskarth Mar 9, 2023
c4a5d23
Update full name
jaskarth Mar 10, 2023
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@jaskarth
jaskarth committed Mar 7, 2023
commit bd1615614119b249377f69c79f77ac97d5d4c4f0
16 changes: 8 additions & 8 deletions src/hotspot/share/opto/mulnode.cpp
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Expand Up @@ -847,9 +847,9 @@ Node *LShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}

// Check for "(x >> C1) << C2" which just masks off low bits
// Check for "(x >> C1) << C2"
if (add1_op == Op_RShiftI || add1_op == Op_URShiftI) {
// Special case C1 == C2
// Special case C1 == C2, which just masks off low bits
if (add1->in(2) == in(2)) {
// Convert to "(x & -(1 << C2))"
return new AndINode(add1->in(1), phase->intcon(-(1 << con)));
Expand Down Expand Up @@ -887,12 +887,12 @@ Node *LShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}

// Check for "((x >> C1) & Y) << C2" which just masks off more low bits
// Check for "((x >> C1) & Y) << C2"
if (add1_op == Op_AndI) {
Node *add2 = add1->in(1);
int add2_op = add2->Opcode();
if (add2_op == Op_RShiftI || add2_op == Op_URShiftI) {
// Special case C1 == C2
// Special case C1 == C2, which just masks off low bits
if (add2->in(2) == in(2)) {
// Convert to "(x & (Y << C2))"
Node* y_sh = phase->transform(new LShiftINode(add1->in(2), phase->intcon(con)));
Expand Down Expand Up @@ -1023,9 +1023,9 @@ Node *LShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}

// Check for "(x >> C1) << C2" which just masks off low bits
// Check for "(x >> C1) << C2"
if (add1_op == Op_RShiftL || add1_op == Op_URShiftL) {
// Special case C1 == C2
// Special case C1 == C2, which just masks off low bits
if (add1->in(2) == in(2)) {
// Convert to "(x & -(1 << C2))"
return new AndLNode(add1->in(1), phase->longcon(-(CONST64(1) << con)));
Expand Down Expand Up @@ -1063,12 +1063,12 @@ Node *LShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
}
}

// Check for "((x >> C1) & Y) << C2" which just masks off more low bits
// Check for "((x >> C1) & Y) << C2"
if (add1_op == Op_AndL) {
Node* add2 = add1->in(1);
int add2_op = add2->Opcode();
if (add2_op == Op_RShiftL || add2_op == Op_URShiftL) {
// Special case C1 == C2
// Special case C1 == C2, which just masks off low bits
if (add2->in(2) == in(2)) {
// Convert to "(x & (Y << C2))"
Node* y_sh = phase->transform(new LShiftLNode(add1->in(2), phase->intcon(con)));
Expand Down
2 changes: 1 addition & 1 deletion test/micro/org/openjdk/bench/vm/compiler/LShiftNodeIdealize.java
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Expand Up @@ -97,14 +97,14 @@ private static int rgbaToAbgr(int i) {
@State(Scope.Benchmark)
public static class BenchState {
int[] ints;
Random random = new Random();

public BenchState() {

}

@Setup
public void setup() {
Random random = new Random(1000);
ints = new int[64];
for (int i = 0; i < 64; i++) {
ints[i] = random.nextInt();
Expand Down