8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' #22456

offamitkumar · 2024-11-29T11:08:45Z

fixes the issue reported by ubsan.

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Issue

JDK-8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' (Bug - P4)

Reviewers

Lutz Schmidt (@RealLucy - Reviewer)
Dean Long (@dean-long - Reviewer)

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bridgekeeper · 2024-11-29T11:09:25Z

👋 Welcome back amitkumar! 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 · 2024-11-29T11:09:46Z

@offamitkumar 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:

8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int'

Reviewed-by: lucy, dlong

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At the time when this comment was updated there had been 53 new commits pushed to the master branch:

293323c: 8340141: C1: rework ciMethod::equals following 8338471
76e874c: 8345319: Fix the tag type in PoolEntry and AnnotationValue
e9f6ba0: 8345293: Fix generational Shenandoah with compact headers
e1910f2: 8345397: Remove from g1HeapRegionRemSet.cpp
3c60f0b: 8345296: AArch64: VM crashes with SIGILL when prctl is disallowed
3eaa761: 8342086: FileInputStream.available() fails with "Incorrect function" for "nul" path (win)
60bd73a: 8342089: Require --enable-native-access to be the same between CDS dump time and run time
2be27e1: 8345393: ProblemList java/util/concurrent/locks/StampedLock/OOMEInStampedLock.java on generic-all JTREG_TEST_THREAD_FACTORY=Virtual
ba50939: 8341649: Regressions with large metaspace apps after 8338526
caf053b: 8337287: Update image in javax.swing.text.Document.insert
... and 43 more: https://git.openjdk.org/jdk/compare/ac2fede165e0ecbfa51f5cc75a3218c51e3528be...master

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.

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openjdk · 2024-11-29T11:10:24Z

@offamitkumar The following label will be automatically applied to this pull request:

hotspot-compiler

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2024-11-29T12:15:09Z

Webrevs

kimbarrett · 2024-11-29T13:50:00Z

src/hotspot/cpu/s390/c1_LIRAssembler_s390.cpp

+                      } else {
+                        __ z_slfi(lreg, c);
+                      }
+                      break;


Would it be simpler to use java_negate(c) (from globalDefinitions.hpp)?

Not sure of that actually. I didn't even know that there exists such helper method. Thanks for making me aware.

I updated current solution in accordance with GCC compiler. So Z don't have a shi instruction which can handle 16-bit numbers, so GCC negates the number and adds it with ahi instruction. Then for number upto 32bits, slfi instruction is emitted for subtraction.

@RealLucy do you have other thoughts on this ?

I agree,
__ z_afi(lreg, java_negate(c));
reads better.

Couldn't you use add2reg_32() for the subtraction as well?

dean-long · 2024-12-02T23:54:34Z

src/hotspot/cpu/s390/c1_LIRAssembler_s390.cpp

+                      if (Immediate::is_simm16(c)) {
+                        __ z_ahi(lreg, c);
+                      } else {
+                        __ z_afi(lreg, c);
+                      }


It seems like it would be better to have code like this in a helper function, instead of making every call site repeat the pattern. Can you use add2reg() here?

add2reg will emit z_aghi instruction which is for 64 bit (register) <- 16 bit (immediate). z_ahi and z_afi are both
32 bit (register) < - 16 bit (immediate), 32 bit (register) <- 32 bit (immediate). So I guess these are better here. Though we can move the logic to new method add2reg_32() method which will do the check and emit correct instruction.

RealLucy · 2024-12-03T10:34:37Z

src/hotspot/cpu/s390/c1_LIRAssembler_s390.cpp

+                      } else {
+                        __ z_slfi(lreg, c);
+                      }
+                      break;


Couldn't you use add2reg_32() for the subtraction as well?

RealLucy · 2024-12-03T10:38:11Z

src/hotspot/cpu/s390/macroAssembler_s390.cpp

@@ -681,6 +681,17 @@ void MacroAssembler::add2reg(Register r1, int64_t imm, Register r2) {
  z_agfi(r1, imm);
 }



I would prefer this method to have the same interface as add2reg(). Of course, that implies a more complex method body. Your choice.

dean-long · 2024-12-03T11:55:53Z

src/hotspot/cpu/s390/macroAssembler_s390.hpp

@@ -156,7 +156,9 @@ class MacroAssembler: public Assembler {
  unsigned int mul_reg64_const16(Register rval, Register work, int cval);

  // Generic operation r1 := r2 + imm.
-  void add2reg(Register r1, int64_t imm, Register r2 = noreg);
+  void add2reg   (Register r1, int64_t imm, Register r2 = noreg);
+  void add2reg_32(Register r1, int64_t imm, Register r2 = noreg);


I don't understand the difference between these two. For both, imm must be a simm_32. I don't think we need add2reg_32.

for add2reg_32 the sum and the first operand, register in this case, are treated as 32 bits signed integers. But for add2reg, sum and operands will be treated as 64 bits signed integers. Immediate value in both case will be 32 bits only.

RealLucy

LGTM.

offamitkumar · 2024-12-04T03:44:16Z

Thanks for reviews & suggestions Lutz, Dean.
/integrate

openjdk · 2024-12-04T03:44:45Z

Going to push as commit 43b337e.
Since your change was applied there have been 65 commits pushed to the master branch:

7ec36bb: 8343001: Adjust XSLT and XPath Extension Function Property
c143138: 8345351: RISC-V: Rename macro-assembler routine cmpxchg_weak to weak_cmpxchg
4237897: 8345341: Fix incorrect log message in JDI stop002t test
82e8aa6: 8345415: Rollback JDK-8301991 change on xmlsecurity_de.properties
05ee562: 8343839: Detect patched modules and abort run-time image link early
0664b51: 8344987: Test serviceability/sa/TestJhsdbJstackPrintVMLocks.java fails: NoClassDefFoundError: jdk/test/lib/Utils
157a434: 8345389: Bump missed copyright years for JDK-8336768
a49f077: 8345221: Replace legacy with new Provider APIs in SunNativeGSS
2be07b5: 8324491: Keyboard layout didn't keep its state if it was changed when dialog was active
f37f64d: 8343736: Test java/awt/Focus/UnaccessibleChoice/AccessibleChoiceTest.java failed: Choice can't be controlled by keyboard
... and 55 more: https://git.openjdk.org/jdk/compare/ac2fede165e0ecbfa51f5cc75a3218c51e3528be...master

Your commit was automatically rebased without conflicts.

openjdk · 2024-12-04T03:44:54Z

@offamitkumar Pushed as commit 43b337e.

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

updates instruction

659836a

openjdk bot changed the title ~~8344304~~ 8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' Nov 29, 2024

openjdk bot added the hotspot-compiler hotspot-compiler-dev@openjdk.org label Nov 29, 2024

offamitkumar marked this pull request as ready for review November 29, 2024 12:11

openjdk bot added the rfr Pull request is ready for review label Nov 29, 2024

kimbarrett reviewed Nov 29, 2024

View reviewed changes

cover lir_add as well

5bdf265

dean-long reviewed Dec 2, 2024

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offamitkumar added 2 commits December 3, 2024 12:09

Merge branch 'master' into ubsan_new

bc70f09

move logic to add2reg_32 & use java_negate()

608cec7

RealLucy suggested changes Dec 3, 2024

View reviewed changes

make similar to add2reg

56a0171

dean-long reviewed Dec 3, 2024

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la has no benefit over add instructions

238cdcd

RealLucy approved these changes Dec 3, 2024

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openjdk bot added the ready Pull request is ready to be integrated label Dec 3, 2024

dean-long approved these changes Dec 3, 2024

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openjdk bot added the integrated Pull request has been integrated label Dec 4, 2024

openjdk bot closed this Dec 4, 2024

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Dec 4, 2024

offamitkumar deleted the ubsan_new branch December 4, 2024 03:46

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8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' #22456

8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' #22456

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		@@ -681,6 +681,17 @@ void MacroAssembler::add2reg(Register r1, int64_t imm, Register r2) {
		z_agfi(r1, imm);
		}

8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' #22456

8344304: [s390x] ubsan: negation of -2147483648 cannot be represented in type 'int' #22456

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