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[GR-69295] Ensure that code base is determined after initializing heap base. #12991

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Merged
graalvmbot merged 1 commit into from
Feb 17, 2026
Merged

[GR-69295] Ensure that code base is determined after initializing heap base. #12991

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1 change: 1 addition & 0 deletions ...om.oracle.svm.core/src/com/oracle/svm/core/graal/nodes/ReadReservedRegisterFixedNode.java
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Expand Up @@ -36,6 +36,7 @@
import jdk.graal.compiler.nodes.spi.NodeLIRBuilderTool;
import jdk.vm.ci.code.Register;

/** @see ReadReservedRegisterFloatingNode */
@NodeInfo(cycles = NodeCycles.CYCLES_0, size = NodeSize.SIZE_0)
public final class ReadReservedRegisterFixedNode extends FixedWithNextNode implements LIRLowerable {
public static final NodeClass<ReadReservedRegisterFixedNode> TYPE = NodeClass.create(ReadReservedRegisterFixedNode.class);
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18 changes: 18 additions & 0 deletions ...oracle.svm.core/src/com/oracle/svm/core/graal/nodes/ReadReservedRegisterFloatingNode.java
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Expand Up @@ -25,6 +25,8 @@
package com.oracle.svm.core.graal.nodes;

import com.oracle.svm.core.FrameAccess;
import com.oracle.svm.core.ReservedRegisters;
import com.oracle.svm.core.graal.snippets.CEntryPointSnippets;

import jdk.graal.compiler.core.common.LIRKind;
import jdk.graal.compiler.graph.NodeClass;
Expand All @@ -36,6 +38,22 @@
import jdk.graal.compiler.nodes.spi.NodeLIRBuilderTool;
import jdk.vm.ci.code.Register;

/**
* A floating node to read a reserved register, which is more efficient because it allows value
* numbering of multiple accesses, including floating nodes that use it as an input. This is safe
* without explicit dependencies because reserved registers generally contain the same value
* throughout a method's execution.
*
* However, these floating reads are also used in the methods that initialize reserved registers
* when entering an isolate (see {@link CEntryPointSnippets}). We carefully use separate methods and
* prevent inlining to avoid that the compiler can move register reads before their writes.
*
* Also, these nodes must not be used for deoptimization target methods because there is no proxying
* at deoptimization entry points for them, so deoptimization would not restore the values.
*
* @see ReservedRegisters
* @see ReadReservedRegisterFixedNode
*/
@NodeInfo(cycles = NodeCycles.CYCLES_0, size = NodeSize.SIZE_0)
public final class ReadReservedRegisterFloatingNode extends FloatingNode implements LIRLowerable {
public static final NodeClass<ReadReservedRegisterFloatingNode> TYPE = NodeClass.create(ReadReservedRegisterFloatingNode.class);
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22 changes: 14 additions & 8 deletions ...m/src/com.oracle.svm.core/src/com/oracle/svm/core/graal/snippets/CEntryPointSnippets.java
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Expand Up @@ -163,9 +163,10 @@ public final class CEntryPointSnippets extends SubstrateTemplates implements Sni
public static final SubstrateForeignCallDescriptor FAIL_FATALLY = SnippetRuntime.findForeignCall(CEntryPointSnippets.class, "failFatally", HAS_SIDE_EFFECT, LocationIdentity.any());
public static final SubstrateForeignCallDescriptor VERIFY_ISOLATE_THREAD = SnippetRuntime.findForeignCall(CEntryPointSnippets.class, "verifyIsolateThread", HAS_SIDE_EFFECT,
LocationIdentity.any());
public static final SubstrateForeignCallDescriptor INIT_CODE_BASE = SnippetRuntime.findForeignCall(CEntryPointSnippets.class, "initCodeBase", HAS_SIDE_EFFECT, LocationIdentity.any());

public static final SubstrateForeignCallDescriptor[] FOREIGN_CALLS = {CREATE_ISOLATE, INITIALIZE_ISOLATE, ATTACH_THREAD, ENSURE_JAVA_THREAD, ENTER_BY_ISOLATE,
DETACH_CURRENT_THREAD, REPORT_EXCEPTION, TEAR_DOWN_ISOLATE, IS_ATTACHED, FAIL_FATALLY, VERIFY_ISOLATE_THREAD};
DETACH_CURRENT_THREAD, REPORT_EXCEPTION, TEAR_DOWN_ISOLATE, IS_ATTACHED, FAIL_FATALLY, VERIFY_ISOLATE_THREAD, INIT_CODE_BASE};

@NodeIntrinsic(value = ForeignCallNode.class)
public static native int runtimeCall(@ConstantNodeParameter ForeignCallDescriptor descriptor, CEntryPointCreateIsolateParameters parameters);
Expand All @@ -185,9 +186,6 @@ public final class CEntryPointSnippets extends SubstrateTemplates implements Sni
@NodeIntrinsic(value = ForeignCallNode.class)
public static native int runtimeCallInitializeIsolate(@ConstantNodeParameter ForeignCallDescriptor descriptor, CEntryPointCreateIsolateParameters parameters);

@NodeIntrinsic(value = ForeignCallNode.class)
public static native int runtimeCallTearDownIsolate(@ConstantNodeParameter ForeignCallDescriptor descriptor);

@NodeIntrinsic(value = ForeignCallNode.class)
public static native boolean runtimeCallIsAttached(@ConstantNodeParameter ForeignCallDescriptor descriptor, Isolate isolate);

Expand All @@ -197,6 +195,9 @@ public final class CEntryPointSnippets extends SubstrateTemplates implements Sni
@NodeIntrinsic(value = ForeignCallNode.class)
public static native void runtimeCallFailFatally(@ConstantNodeParameter ForeignCallDescriptor descriptor, int code, CCharPointer message);

@NodeIntrinsic(value = ForeignCallNode.class)
public static native void runtimeCallInitCodeBase(@ConstantNodeParameter ForeignCallDescriptor descriptor);

@Fold
static boolean hasHeapBase() {
return ImageSingletons.lookup(CompressEncoding.class).hasBase();
Expand All @@ -210,8 +211,13 @@ private static void setHeapBase(PointerBase heapBase) {
}
}

@Uninterruptible(reason = CALLED_FROM_UNINTERRUPTIBLE_CODE)
@NeverInline("Heap base register is set in caller, prevent reads from floating before that.")
/**
* Initializes the code base register, which accesses the heap using the heap base register. To
* prevent the compiler from moving reads from this method to before the heap base register is
* initialized in a caller, this method is a foreign call target that does not get inlined.
*/
@SubstrateForeignCallTarget(stubCallingConvention = false)
@Uninterruptible(reason = "Thread state not yet set up.")
private static void initCodeBase() {
CodePointer codeBase;
if (ImageLayerBuildingSupport.buildingImageLayer()) {
Expand Down Expand Up @@ -243,7 +249,7 @@ public static void earlyInitHeapBase(PointerBase heapBase) {
public static void initBaseRegisters(PointerBase heapBase) {
setHeapBase(heapBase);
if (SubstrateOptions.useRelativeCodePointers()) {
initCodeBase();
runtimeCallInitCodeBase(INIT_CODE_BASE);
}
}

Expand Down Expand Up @@ -683,7 +689,7 @@ private static int detachCurrentThread() {

@Snippet(allowMissingProbabilities = true)
public static int tearDownIsolateSnippet() {
return runtimeCallTearDownIsolate(TEAR_DOWN_ISOLATE);
return runtimeCall(TEAR_DOWN_ISOLATE);
}

@SubstrateForeignCallTarget(stubCallingConvention = false)
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