8353500: [s390x] Intrinsify Unsafe::setMemory #24480
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with patch: without patch: |
RealLucy
suggested changes
Apr 7, 2025
| __ z_risbg(tmp, size, 32, 128/* risbgz */ + 63, 64 - exact_log2(2 * elem_size), 0); // just do the right shift and set cc | ||
| __ z_bre(L_Tail); | ||
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| __ align(16); // loop alignment |
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align(32) would be more helpful:
- instruction engine fetches octoword (32 bytes) bundles.
- Tight loop is < 32 byes -> all in one bundle, does not cross cache line boundary.
| // multiple of 2 | ||
| do_setmemory_atomic_loop(2, dest, size, byteVal, _masm); | ||
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| __ align(16); |
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What is this alignment good for?
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Branch target alignment. There is no fallthrough path from before this point. Should it be 32?
| __ z_ogrk(rScratch1, dest, size); | ||
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| __ z_nill(rScratch1, 7); | ||
| __ z_bre(L_fill8Bytes); // branch if 0 |
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Pls use z_braz() to reflect check semantics
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| __ z_nill(rScratch1, 3); | ||
| __ z_bre(L_fill4Bytes); // branch if 0 |
| __ z_bre(L_fill4Bytes); // branch if 0 | ||
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| __ z_nill(rScratch1, 1); | ||
| __ z_brne(L_fillBytes); // branch if not 0 |
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Pls use z_brnaz() to reflect check semantics
| @@ -415,10 +415,13 @@ inline void Assembler::z_rosbg( Register r1, Register r2, int64_t spos3, int64_t | |||
| } | |||
| inline void Assembler::z_risbg( Register r1, Register r2, int64_t spos3, int64_t epos4, int64_t nrot5, bool zero_rest) { // Rotate then INS selected bits. -- z196 | |||
| const int64_t len = 48; | |||
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Changes are not necessary if bool zero_rest is used to control what happens to untouched destination bits.
| // inc_counter_np(SharedRuntime::_unsafe_set_memory_ctr); | ||
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| { | ||
| NearLabel L_fill8Bytes, L_fill4Bytes, L_fillBytes, L_exit; |
| __ bind(L_Loop); | ||
| __ store_sized_value(byteVal, Address(dest, 0), elem_size); | ||
| __ store_sized_value(byteVal, Address(dest, elem_size), elem_size); | ||
| __ z_agfi(dest, 2 * elem_size); |
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Since this is taken from #24254: Maybe you can review that one, too? |
| Register tmp = Z_R1; // R1 is free at this point | ||
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| if (elem_size > 1) { | ||
| __ rotate_then_insert(byteVal, byteVal, 64 - 2 * 8 , 63 - 8, 8, 0); |
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The last argument seems to be a bool. The value should better be false.
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| __ z_nill(rScratch1, 7); | ||
| __ z_braz(L_fill8Bytes); // branch if 0 | ||
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Unsafe::setMemory intrinsic implementation for s390x.
Stub Code:
Progress
Issue
Reviewing
Using
gitCheckout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/24480/head:pull/24480$ git checkout pull/24480Update a local copy of the PR:
$ git checkout pull/24480$ git pull https://git.openjdk.org/jdk.git pull/24480/headUsing Skara CLI tools
Checkout this PR locally:
$ git pr checkout 24480View PR using the GUI difftool:
$ git pr show -t 24480Using diff file
Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/24480.diff
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