Running CompileTheWorld test with java.base module fail with OutOfMemoryError when running the test with -Xmx1024m.
Looking at heap dump file generated when running with -XX:+HeapDumpOnOutOfMemoryError shows that the heap is mostly occupied by BlockMap<BlockData> blockData array referenced from org.graalvm.compiler.lir.alloc.lsra.LinearScan.

Class Name | Shallow Heap | Retained Heap
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org.graalvm.compiler.lir.alloc.lsra.ssa.SSALinearScan @ 0x3069dafe0 | 96 | 940,772,936
|- <class> class org.graalvm.compiler.lir.alloc.lsra.ssa.SSALinearScan @ 0x302a65c08 | 8 | 88
|- registers jdk.vm.ci.code.RegisterArray @ 0x30298a868 | 24 | 272
|- debug org.graalvm.compiler.debug.DebugContext @ 0x30415b6e0 | 72 | 168
|- sortedBlocks org.graalvm.compiler.core.common.cfg.AbstractBlockBase[48215] @ 0x306d269a0| 192,880 | 192,880
|- intervalEndMarker org.graalvm.compiler.lir.alloc.lsra.Interval @ 0x30703d9e8 | 96 | 184
|- rangeEndMarker org.graalvm.compiler.lir.alloc.lsra.Range @ 0x30703da48 | 24 | 24
|- res org.graalvm.compiler.hotspot.HotSpotLIRGenerationResult @ 0x3073caa50 | 56 | 192
|- ir org.graalvm.compiler.lir.LIR @ 0x3073caaa0 | 48 | 4,257,912
|- frameMapBuilder org.graalvm.compiler.lir.amd64.AMD64FrameMapBuilder @ 0x3073cb528 | 40 | 40,512
|- moveFactory org.graalvm.compiler.hotspot.amd64.AMD64HotSpotMoveFactory @ 0x30896b118 | 16 | 40
|- registerAttributes jdk.vm.ci.code.RegisterAttributes[57] @ 0x30a389ed0 | 248 | 248
|- blockData org.graalvm.compiler.core.common.cfg.BlockMap @ 0x30a4153f0 | 16 | 929,748,544
| |- <class> class org.graalvm.compiler.core.common.cfg.BlockMap @ 0x302a4c700 | 0 | 0
| |- data java.lang.Object[48215] @ 0x30a415400 | 192,880 | 929,748,528
| | |- <class> class java.lang.Object[] @ 0x3028396d8 | 0 | 0
| | |- [33288] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915bd8 | 32 | 24,992
| | |- [33287] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915bf8 | 32 | 24,992
| | |- [33286] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915c18 | 32 | 24,992
| | |- [33285] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915c38 | 32 | 24,992
| | |- [33284] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915c58 | 32 | 24,992
| | |- [33283] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915c78 | 32 | 24,992
| | |- [33282] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915c98 | 32 | 24,992
| | |- [33281] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915cb8 | 32 | 24,992
| | |- [33280] org.graalvm.compiler.lir.alloc.lsra.LinearScan$BlockData @ 0x306915cd8 | 32 | 24,992
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As you can see blockData consists of 48215 elements which occupy most of the heap.