8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion #15360

albertnetymk · 2023-08-21T12:25:12Z

Use unsigned type for heap-region-size related shifts in HeapRegion.

Test: tier1-3

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JDK-8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion (Enhancement - P4)

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Thomas Schatzl (@tschatzl - Reviewer)
Ivan Walulya (@walulyai - Reviewer)

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bridgekeeper · 2023-08-21T12:26:44Z

👋 Welcome back ayang! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2023-08-21T12:29:06Z

@albertnetymk The following labels will be automatically applied to this pull request:

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mlbridge · 2023-08-21T12:32:34Z

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01: Full - Incremental (49866dac)
00: Full (26e1e298)

albertnetymk · 2023-08-25T12:12:01Z

/label hotspot-gc

openjdk · 2023-08-25T12:13:20Z

@albertnetymk
The hotspot-gc label was successfully added.

tschatzl · 2023-08-29T08:16:33Z

src/hotspot/share/gc/g1/g1Arguments.cpp

+  uint region_size_log_mb = HeapRegion::LogOfHRGrainBytes > LOG_M
+                          ? HeapRegion::LogOfHRGrainBytes - LOG_M
+                          : 0;


I would just assert that HeapRegion::LogOfHRGrainBytes >= LOG_M here. People messing with with minimum region size would need to check this code anyway.

Further, LOG_M should probably be calculated as log2_exact(HeapRegion::min_size()) instead of using the constant directly (and renamed appropriately, something like Log[Of]MinHeapRegionSize/GrainBytes).

Then there would be no need to do the maximum calculation (my original suggestion would have been MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0u) btw)

Checking how it's used around G1RemSetArrayOfCardsEntriesBase, log_m is more about 1MB. The very fact that min-heap-region is 1M seems an accident. Kept the original name and added assertion.

tschatzl · 2023-08-29T08:17:36Z

src/hotspot/share/gc/g1/g1Arguments.cpp


  if (FLAG_IS_DEFAULT(G1RemSetArrayOfCardsEntries)) {
-    uint max_cards_in_inline_ptr = G1CardSetConfiguration::max_cards_in_inline_ptr(HeapRegion::LogOfHRGrainBytes - CardTable::card_shift());
+    uint max_cards_in_inline_ptr = G1CardSetConfiguration::max_cards_in_inline_ptr(HeapRegion::LogCardsPerRegion);


Not sure how this change has anything to do with -Wconversion, but okay :)

tschatzl · 2023-08-29T08:17:42Z

src/hotspot/share/gc/g1/g1CardTable.inline.hpp

 inline uint G1CardTable::region_idx_for(CardValue* p) {
  size_t const card_idx = pointer_delta(p, _byte_map, sizeof(CardValue));
-  return (uint)(card_idx >> (HeapRegion::LogOfHRGrainBytes - _card_shift));
+  return (uint)(card_idx >> HeapRegion::LogCardsPerRegion);


Not sure how this change has anything to do with -Wconversion but okay :)

tschatzl · 2023-08-29T08:38:36Z

src/hotspot/share/jvmci/vmStructs_jvmci.cpp


 #define VM_STRUCTS_JVMCI_G1GC(nonstatic_field, static_field) \
-  static_field(HeapRegion, LogOfHRGrainBytes, int)
+  static_field(HeapRegion, LogOfHRGrainBytes, uint32_t)


Suggested change

static_field(HeapRegion, LogOfHRGrainBytes, uint32_t)

static_field(HeapRegion, LogOfHRGrainBytes, uint)

Seems to compile just fine here.

That was my original attempt, but JVMCI related tests failed with uint.

tschatzl · 2023-08-29T09:06:23Z

src/hotspot/share/gc/g1/c1/g1BarrierSetC1.cpp

    __ move(xor_res, xor_shift_res);
    __ unsigned_shift_right(xor_shift_res,
-                            LIR_OprFact::intConst(HeapRegion::LogOfHRGrainBytes),
+                            LIR_OprFact::intConst(static_cast<jint>(HeapRegion::LogOfHRGrainBytes)),


One could maybe argue that this should be a checked_cast, but given that the value bounds are known there is no point...

tschatzl

Lgtm.

openjdk · 2023-08-29T14:37:38Z

@albertnetymk This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion

Reviewed-by: tschatzl, iwalulya

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 4 new commits pushed to the master branch:

e22762c: 8314932: G1: Fix -Wconversion warnings for simple cases inside g1 folder
762b652: 8314573: G1: Heap resizing at Remark does not take existing eden regions into account
a4e97aa: 8314753: Remove support for @beaninfo, @todo, @since.unbundled, and @note
5cc64cc: 8309463: IGV: Dynamic graph layout algorithm

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

albertnetymk · 2023-08-30T09:35:36Z

Thanks for the review.

/integrate

openjdk · 2023-08-30T09:36:35Z

Going to push as commit cb3f968.
Since your change was applied there have been 11 commits pushed to the master branch:

876a725: 8315206: RISC-V: hwprobe query is_set return wrong value
ed1ea5f: 8314024: SIGSEGV in PhaseIdealLoop::build_loop_late_post_work due to bad immediate dominator info
f3aeb02: 8315213: java/lang/ProcessHandle/TreeTest.java test enhance output of children
1e7e2bc: 8315214: Do not run sun/tools/jhsdb tests concurrently
ce2a7ea: 8314056: Remove runtime platform check from frem/drem
1c598c2: 8312428: PKCS11 tests fail with NSS 3.91
b2728cb: 8189685: need PerfMemory class update and a volatile_static_field support in VMStructs
e22762c: 8314932: G1: Fix -Wconversion warnings for simple cases inside g1 folder
762b652: 8314573: G1: Heap resizing at Remark does not take existing eden regions into account
a4e97aa: 8314753: Remove support for @beaninfo, @todo, @since.unbundled, and @note
... and 1 more: https://git.openjdk.org/jdk/compare/1d0250709a6ee97f5647edff589761bd9d0b7f4c...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-08-30T09:36:42Z

@albertnetymk Pushed as commit cb3f968.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

g1-heap-region-log-uint

26e1e29

openjdk bot changed the title ~~8314651~~ 8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion Aug 21, 2023

openjdk bot added the rfr Pull request is ready for review label Aug 21, 2023

openjdk bot added graal graal-dev@openjdk.org hotspot hotspot-dev@openjdk.org labels Aug 21, 2023

openjdk bot added the hotspot-gc hotspot-gc-dev@openjdk.org label Aug 25, 2023

tschatzl suggested changes Aug 29, 2023

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albertnetymk added 2 commits August 29, 2023 14:45

Merge branch 'master' into g1-heap-region-log-uint

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walulyai approved these changes Aug 29, 2023

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openjdk bot closed this Aug 30, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Aug 30, 2023

albertnetymk deleted the g1-heap-region-log-uint branch August 30, 2023 09:37

	static_field(HeapRegion, LogOfHRGrainBytes, uint32_t)
	static_field(HeapRegion, LogOfHRGrainBytes, uint)

8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion #15360

8314651: G1: Fix -Wconversion warnings in static fields of HeapRegion #15360

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