On Fri, 7 Aug 2026 14:14:32 GMT, Fredrik Bredberg <[email protected]> wrote:
> The main objectives for this PR are: > 1) Compact Object Headers needs the Object Monitor Table to work. > 2) Both Compact Object Headers > ([JDK-8360700](https://bugs.openjdk.org/browse/JDK-8360700)) and Object > Monitor Table ([JDK-8379782](https://bugs.openjdk.org/browse/JDK-8379782)) > are now enabled by default. > 3) If we always use the Object Monitor Table, we will free up lots of bits > in the markword, that could be of use to others (read GC). > 4) If we don't need to maintain any "monitor pointer in the mark word" code, > we will simplify the code base. > > Therefore this PR will remove the `UseObjectMonitorTable` flag and related > code. > > Note that this PR only removes the most obvious use of the > `UseObjectMonitorTable` in the code base. This is to ease the burden on the > reviewers. [JDK-8389938](https://bugs.openjdk.org/browse/JDK-8389938) has > been created to finalize the work by removing the less obvious code, like no > longer used mark word code in different GCs. > > The code has passed tier1-7 testing on supported platforms and smoke testing > using QEMU on `RISC-V`, `PowerPC` and `s390`. > > --------- > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). You might want to merge the master branch, It seems there is one more instance added in valhalla. ```diff diff --git a/src/hotspot/cpu/s390/macroAssembler_s390.cpp b/src/hotspot/cpu/s390/macroAssembler_s390.cpp index 08ae5af194c..e8971e7630e 100644 --- a/src/hotspot/cpu/s390/macroAssembler_s390.cpp +++ b/src/hotspot/cpu/s390/macroAssembler_s390.cpp @@ -4265,15 +4265,6 @@ void MacroAssembler::test_oop_prototype_bit(Register oop, Register temp_reg, int assert(test_bit <= 0xFFFF, "must fit in low 16 bits for z_tmll"); // Load mark word z_lg(temp_reg, oopDesc::mark_offset_in_bytes(), oop); - if (!UseObjectMonitorTable) { - Label test_mark_word; - // If unlocked bit is set we can directly use the mark word - z_tmll(temp_reg, markWord::unlocked_value); - z_brnaz(test_mark_word); - // Slow path: use klass prototype - load_prototype_header(temp_reg, oop); - bind(test_mark_word); - } z_tmll(temp_reg, test_bit); // Use branch_optimized to handle both near and far branches automatically branch_optimized(jmp_set ? Assembler::bcondNotAllZero : Assembler::bcondAllZero, jmp_label); With above diff, I did testing on s390x, and result look clean. ------------- PR Review: https://git.openjdk.org/jdk/pull/32257#pullrequestreview-4890674530
