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Merged
merged 1 commit into from
Oct 17, 2025
Merged

[proposal] Extended Constant Expressions #1075

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1 change: 1 addition & 0 deletions README.md
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Expand Up @@ -95,6 +95,7 @@ If you have an interest in working on any of these please reach out in Zulip!
* [x] Compiler out of experimental
* [x] Exception Handling
* [x] Threads Support
* [x] Extended Constant Expressions
* [ ] GC Support
* in progress

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6 changes: 6 additions & 0 deletions runtime-tests/pom.xml
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Expand Up @@ -120,6 +120,9 @@
<wast>proposals/exception-handling/throw.wast</wast>
<wast>proposals/exception-handling/throw_ref.wast</wast>
<wast>proposals/exception-handling/try_table.wast</wast>
<wast>proposals/extended-const/data.wast</wast>
<wast>proposals/extended-const/elem.wast</wast>
<wast>proposals/extended-const/global.wast</wast>
<wast>proposals/function-references/binary.wast</wast>
<wast>proposals/function-references/br_on_non_null.wast</wast>
<wast>proposals/function-references/br_on_null.wast</wast>
Expand Down Expand Up @@ -375,6 +378,9 @@
<wast>proposals/exception-handling/throw.wast</wast>
<wast>proposals/exception-handling/throw_ref.wast</wast>
<wast>proposals/exception-handling/try_table.wast</wast>
<wast>proposals/extended-const/data.wast</wast>
<wast>proposals/extended-const/elem.wast</wast>
<wast>proposals/extended-const/global.wast</wast>
<wast>proposals/function-references/binary.wast</wast>
<wast>proposals/function-references/br_on_non_null.wast</wast>
<wast>proposals/function-references/br_on_null.wast</wast>
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74 changes: 64 additions & 10 deletions runtime/src/main/java/com/dylibso/chicory/runtime/ConstantEvaluators.java
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Expand Up @@ -2,9 +2,11 @@

import static com.dylibso.chicory.wasm.types.OpCode.GLOBAL_GET;

import com.dylibso.chicory.wasm.MalformedException;
import com.dylibso.chicory.wasm.types.Instruction;
import com.dylibso.chicory.wasm.types.ValType;
import com.dylibso.chicory.wasm.types.Value;
import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.List;

Expand All @@ -16,44 +18,96 @@ public static long[] computeConstantValue(Instance instance, Instruction[] expr)
}

public static long[] computeConstantValue(Instance instance, List<Instruction> expr) {
long tos = -1L;
var stack = new ArrayDeque<long[]>();
for (var instruction : expr) {
switch (instruction.opcode()) {
case I32_ADD:
{
var x = (int) stack.pop()[0];
var y = (int) stack.pop()[0];
stack.push(new long[] {x + y});
break;
}
case I32_SUB:
{
var x = (int) stack.pop()[0];
var y = (int) stack.pop()[0];
stack.push(new long[] {y - x});
break;
}
case I32_MUL:
{
var x = (int) stack.pop()[0];
var y = (int) stack.pop()[0];
int res = x * y;
stack.push(new long[] {res});
break;
}
case I64_ADD:
{
var x = stack.pop()[0];
var y = stack.pop()[0];
stack.push(new long[] {x + y});
break;
}
case I64_SUB:
{
var x = stack.pop()[0];
var y = stack.pop()[0];
stack.push(new long[] {y - x});
break;
}
case I64_MUL:
{
var x = stack.pop()[0];
var y = stack.pop()[0];
stack.push(new long[] {x * y});
break;
}
case V128_CONST:
return new long[] {instruction.operand(0), instruction.operand(1)};
{
stack.push(new long[] {instruction.operand(0), instruction.operand(1)});
break;
}
case F32_CONST:
case F64_CONST:
case I32_CONST:
case I64_CONST:
case REF_FUNC:
{
tos = instruction.operand(0);
stack.push(new long[] {instruction.operand(0)});
break;
}
case REF_NULL:
{
tos = Value.REF_NULL_VALUE;
stack.push(new long[] {Value.REF_NULL_VALUE});
break;
}
case GLOBAL_GET:
{
var idx = (int) instruction.operand(0);
if (instance.global(idx).getType().equals(ValType.V128)) {
return new long[] {
instance.global(idx).getValueLow(),
instance.global(idx).getValueHigh()
};
stack.push(
new long[] {
instance.global(idx).getValueLow(),
instance.global(idx).getValueHigh()
});
} else {
return new long[] {instance.global(idx).getValueLow()};
stack.push(new long[] {instance.global(idx).getValueLow()});
}
break;
}
case END:
{
break;
}
default:
throw new MalformedException(
"Invalid instruction in constant value" + instruction);
}
}
return new long[] {tos};

return stack.pop();
}

public static Instance computeConstantInstance(Instance instance, List<Instruction> expr) {
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64 changes: 33 additions & 31 deletions wasm/src/main/java/com/dylibso/chicory/wasm/Validator.java
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Expand Up @@ -27,6 +27,7 @@
import com.dylibso.chicory.wasm.types.TagType;
import com.dylibso.chicory.wasm.types.ValType;
import com.dylibso.chicory.wasm.types.Value;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
Expand Down Expand Up @@ -526,57 +527,58 @@ void validateElements() {
void validateGlobals() {
for (Global g : module.globalSection().globals()) {
validateConstantExpression(g.initInstructions(), g.valueType());
if (g.mutabilityType() == MutabilityType.Const && g.initInstructions().size() > 1) {
throw new InvalidException("constant expression required");
}
}
}

private void validateConstantExpression(
List<? extends Instruction> expr, ValType expectedType) {
validateValueType(expectedType);
int allFuncCount = this.functionImports.size() + module.functionSection().functionCount();
int constInstrCount = 0;
var valTypeStack = new ArrayDeque<ValType>();
for (var instruction : expr) {
ValType exprType = null;

switch (instruction.opcode()) {
case I32_CONST:
exprType = ValType.I32;
constInstrCount++;
valTypeStack.push(ValType.I32);
break;
case I32_ADD:
case I32_SUB:
case I32_MUL:
valTypeStack.pop();
valTypeStack.pop();
valTypeStack.push(ValType.I32);
break;
case I64_CONST:
exprType = ValType.I64;
constInstrCount++;
valTypeStack.push(ValType.I64);
break;
case I64_ADD:
case I64_SUB:
case I64_MUL:
valTypeStack.pop();
valTypeStack.pop();
valTypeStack.push(ValType.I64);
break;
case F32_CONST:
exprType = ValType.F32;
constInstrCount++;
valTypeStack.push(ValType.F32);
break;
case F64_CONST:
exprType = ValType.F64;
constInstrCount++;
valTypeStack.push(ValType.F64);
break;
case V128_CONST:
exprType = ValType.V128;
constInstrCount++;
valTypeStack.push(ValType.V128);
break;
case REF_NULL:
{
int operand = (int) instruction.operand(0);
exprType = valType(ValType.ID.RefNull, operand);
constInstrCount++;
valTypeStack.push(valType(ValType.ID.RefNull, operand));
break;
}
case REF_FUNC:
{
constInstrCount++;
int idx = (int) instruction.operand(0);
exprType = valType(ValType.ID.Ref, getFunctionType(idx));
valTypeStack.push(valType(ValType.ID.Ref, getFunctionType(idx)));
if (idx < 0 || idx > allFuncCount) {
throw new InvalidException("unknown function " + idx);
}

break;
}
case GLOBAL_GET:
Expand All @@ -589,15 +591,14 @@ private void validateConstantExpression(
"constant expression required, initializer expression"
+ " cannot reference a mutable global");
}
exprType = global.valueType();
valTypeStack.push(global.valueType());
} else {
throw new InvalidException(
"unknown global "
+ idx
+ ", initializer expression can only reference"
+ " an imported global");
}
constInstrCount++;
break;
}
case END:
Expand All @@ -608,18 +609,19 @@ private void validateConstantExpression(
+ " encountered: "
+ instruction);
}
}

if (valTypeStack.size() < 1) {
throw new InvalidException("type mismatch, no constant expressions found");
}
if (valTypeStack.size() != 1) {
throw new InvalidException(
"type mismatch, values remaining on the stack after evaluation");
} else {
var exprType = valTypeStack.pop();
if (exprType != null && !ValType.matches(exprType, expectedType)) {
throw new InvalidException("type mismatch");
}

// There must be at most one constant instruction.
if (constInstrCount > 1) {
throw new InvalidException("type mismatch, multiple constant expressions found");
}
}
if (constInstrCount <= 0) {
throw new InvalidException("type mismatch, no constant expressions found");
}
}

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