On Tue, 18 Aug 2026 14:25:36 GMT, Boris Ulasevich <[email protected]> wrote:
>> These fixes address a series of failures reproducible when building arm32 >> natively on an arm32 platform (not cross-compilation), in both release and >> fastdebug modes. >> >> 1. jniFastGetField_arm.cpp: use offset_shift >> >> After JEP 401 was integrated, jfieldIDWorkaround's offset_shift changed from >> 2 to 3. ARM32 is the only port where the shift was hardcoded as the literal >> 2 in JNI_FastGetField::generate_fast_get_int_field0. Other architectures >> take this value from the jfieldIDWorkaround::offset_shift constant and >> picked up the change automatically. This caused java.io.FileDescriptor's int >> fd field to be read incorrectly in the native fdval() function (IOUtil.c, >> libnio.so), which made the JVM hang during module loading at the >> COMPILE_CREATE_SYMBOLS step of the JDK build (fd was incorrectly decoded as >> 0 -- a blocking read from stdin). Fix: use the >> jfieldIDWorkaround::offset_shift constant instead of the hardcoded literal. >> >> 2. oops/symbol.hpp: class alignas(8) Symbol >> >> JEP 401 widened VerificationType::TypeMask from 0x3 to 0x7, reserving a >> third bit for inline types. As a result is_reference() now requires a >> Symbol* to be 8-byte aligned. On 32-bit a Symbol sits at offset 4 inside a >> SymbolTable node, so is_reference() is always false and verification of any >> class fails with VerifyError. This only happens in release builds: in debug >> builds the node carries an extra DEBUG_ONLY field, which pushes the Symbol >> to offset 8. Fix: alignas(8) makes Symbol 8-byte aligned. On 64-bit the >> layout is unchanged. >> >> 3. make/autoconf/jdk-options.m4: disable cds-archive-preview for 32-bit >> systems >> >> The build unconditionally generates a preview CDS archive, but value objects >> are not supported on 32-bit: InlineKlass::InlineKlass hits assert "Should >> not be called in 32 bit mode" (markWord.hpp), and the jdk-image step fails >> while dumping classes_preview.jsa. Fix: make the cds-archive-preview option >> unavailable on non-64-bit platforms. >> >> 4. cds/archiveUtils.cpp: additional check for minimal gap size >> >> This fixes a fastdebug build failure at the generate-link-opt-data step: >> assert(is_aligned(gap_bytes(), SharedSpaceObjectAlignment)) failed. It is >> related to ee90f00b3b3 (8376822, UseCompactObjectHeaders: fill Klass >> alignment gaps), not to JEP 401. That change started inserting an alignment >> gap in front of a buffered Klass and recording it for later reuse. On arm32 >> the gap is always 4 bytes -- nothing can ever fit into it, and AllocGap >> fails its precondition. Fix: onl... > > Boris Ulasevich has updated the pull request incrementally with one > additional commit since the last revision: > > Use CHECK_AVAILABLE to explain why cds-archive-preview is unavailable This has been verified on an AWS Graviton with an ARM32 environment: the build hangs without the patch, but finishes with it. ------------- PR Comment: https://git.openjdk.org/jdk/pull/32402#issuecomment-5331958200
