Integrated: 8334232: Optimize C1 classes layout

[Neethu Prasad]

On Wed, 3 Jul 2024 20:36:07 GMT, Neethu Prasad <nprasad at openjdk.org> wrote:

> **Notes**
> 
> Rearrange C1 class fields to optimize footprint.
> 
> 
> **Verification**
> 
> 1. Ran tier2_compiler, hotspot_compiler, tier 1 & tier 2 tests.
> 2. Ran pahole on 64 bit machine post re-ordering and verified that there are no holes / reduction in total bytes.
> 
> | Class | Size | Cachelines | Holes | Sum holes | Last Cacheline | Padding |
> | ----- | ----- | ---------- | ----- | ---------- | --------------- | -------- |
> | Instruction | 96 -> 88 | 2 -> 2  |  2 -> 0  |  8 -> 0  | 32 -> 24  | 1 -> 1  |
> | Intrinsic | 136 -> 120 | 3 -> 2  |  1 -> 1  | 4 -> 96   |  8 ->  56 |  4-> 0 |
> | LIR_Address | 48 -> 40 | 1 -> 1  |  1-> 0  | 4 -> 0  |  48 -> 40 | 7 -> 3   |
> | LIR_Op2 | 128 -> 120  | 2 -> 2  | 2 -> 0  |  11 -> 0  | N/A -> 56  | 4 -> 7  |
> | LIR_Op4 | 136 -> 128  | 3 -> 2  | 1-> 0  |  7 -> 0 |  8-> 0  |  4 ->  3 |
> | LIR_OpAllocArray  | 120 -> 112  | 2 -> 2  | 1-> 0   |  7 -> 0  | 56 -> 48 |  7 -> 6 |
> |LIR_OpTypeCheck  | 144 -> 136  | 3 -> 3  | 1-> 0  |  7 -> 0  |  16 ->  8 |  3 -> 2  |
> 
> 
> 
> /* class CompilationResourceObj <ancestor>; */   /*     0     0 */
> 
> 	/* XXX last struct has 1 byte of padding */
> 
> 	int ()(void) * *           _vptr.Instruction;    /*     0     8 */
> 	int                        _id;                  /*     8     4 */
> 	int                        _use_count;           /*    12     4 */
> 	int                        _pin_state;           /*    16     4 */
> 	unsigned int               _flags;               /*    20     4 */
> 	class ValueType *          _type;                /*    24     8 */
> 	class Instruction *        _next;                /*    32     8 */
> 	class Instruction *        _subst;               /*    40     8 */
> 	class LIR_Opr             _operand;              /*    48     8 */
> 	class ValueStack *         _state_before;        /*    56     8 */
> 	/* --- cacheline 1 boundary (64 bytes) --- */
> 	class ValueStack *         _exception_state;     /*    64     8 */
> 	class XHandlers *          _exception_handlers;  /*    72     8 */
> protected:
> 
> 	class BlockBegin *         _block;               /*    80     8 */
> public:
> 
> 
> 	/* Bitfield combined with previous fields */
> 
> 	static const int                  no_bci;        /*     0     0 */
> protected:
> 
> public:
> 
> 
> 	/* size: 88, cachelines: 2, members: 14, static members: 1 */
> 	/* paddings: 1, sum paddings: 1 */
> 	/* last cacheline: 24 bytes */
> };
> 
> 
> 
> 
> class LIR_Address : public LIR_OprPtr {
> public:
> 
> 	/* class LIR_OprPtr          <ancestor>; */      /*     0     8 */
> 	class LIR_Opr             _base;              ...

This pull request has now been integrated.

Changeset: 24f67d02
Author:    Neethu Prasad <nprasad at openjdk.org>
Committer: Vladimir Kozlov <kvn at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/24f67d0254c08a668d24f28ec0fa768ef10feed5
Stats:     47 lines in 3 files changed: 21 ins; 21 del; 5 mod

8334232: Optimize C1 classes layout

Reviewed-by: phh, kvn

-------------

PR: https://git.openjdk.org/jdk/pull/20017