[Wasm RyuJIT] Start generating relocations for call_indirect by kg · Pull Request #124205 · dotnet/runtime

kg · 2026-02-10T00:09:20Z

Add various relocation types from the wasm linking spec to CorInfoReloc and RelocType
Add new instruction formats for relocated constant payloads like IF_CALL and IF_MEMADDR
Use relocations in emitIns_Call
Add pseudo-instructions for relocated i32_const
Make WasmTypeNode an ISymbolNode so it can be a reloc target

dotnet-policy-service · 2026-02-10T00:09:57Z

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Copilot

Pull request overview

This PR updates the WASM JIT emitter to begin supporting relocatable immediates for call_indirect, by representing certain immediates as “padded reloc” placeholders and centralizing constant emission logic.

Changes:

Use getWasmTypeSymbol and store the returned handle in the call_indirect immediate as a relocatable constant.
Teach instrDesc::idCodeSize() to account for padded reloc sizes for call_indirect immediates.
Add helper routines to emit either normal (S)LEB128 constants or fixed-size padded relocation placeholders.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/coreclr/jit/emitwasm.h	Declares new helper APIs for emitting padded relocations/constants.
src/coreclr/jit/emitwasm.cpp	Implements padded-reloc emission and switches `call_indirect` immediate handling to use a relocatable constant path.

…DEX_LEB'

kg · 2026-02-10T03:07:00Z

Current status:

Generating: N003 (???,???) [000001] --CXG+-----                         *  CALL r2r_ind void   Program:voidFunc()
Added IP mapping: 0x0001 STACK_EMPTY CALL_INSTRUCTION (G_M45341_IG02,ins#4,ofs#8)
IN0005:             i32.const 0
IN0006:             i32.load 0 0
IN0007:             call_indirect 4611686018431713352 0      ;; Program:voidFunc()

~~~ snip ~~~

IN0005: 00001E      i32.const 0
IN0006: 000020      i32.load 0 0
recordRelocation: 000001D2A75F2E7C (rw: 000001D2A75F2E7C) => 4000000000420048, type 28 (relocType), delta 0
Unhandled exception. ILCompiler.CodeGenerationFailedException: Code generation failed for method '[wasm-test]Program.callVoidFunc()'
 ---> System.ArgumentException: Unsupported relocation type: R_WASM_TYPE_INDEX_LEB
   at Internal.JitInterface.CorInfoImpl.GetRelocType(CorInfoReloc)
   at Internal.JitInterface.CorInfoImpl.recordRelocation(Void*, Void*, Void*, CorInfoReloc, Int32)
   at Internal.JitInterface.CorInfoImpl._recordRelocation(IntPtr, IntPtr*, Void*, Void*, Void*, CorInfoReloc, Int32)
   --- End of inner exception stack trace ---
   at Internal.JitInterface.CorInfoImpl.CompileMethodInternal(IMethodNode, MethodIL)

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 5 comments.

Copilot

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

kg · 2026-02-10T17:52:35Z

cc @dotnet/jit-contrib

I'm not sure we need to actually generate a valid ULEB/SLEB fill pattern here because R2R is going to be replacing the fill pattern with the real value.
I'm also not sure we need to pad relocations in the first place, since we care about code size ideally when R2R replaces the placeholders with the relocated values it should be shrinking the relocations as necessary.

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

kg · 2026-02-11T23:56:40Z

It pads the (U|S)LEB values to 5 bytes now using the algorithm from runtimelab. For completeness's sake I'm manually validating them for the whole 32-bit space right now since I can't manually test them inside of crossgen yet (we're not generating that type of reloc anywhere.)

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

SingleAccretion

LGTM with minor comments.

AndyAyersMS

LGTM

Copilot

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 4 comments.

…124205) * Add various relocation types from the wasm linking spec to CorInfoReloc and RelocType * Add new instruction formats for relocated constant payloads like IF_FUNCIDX and IF_MEMADDR * Use relocations in emitIns_Call * Add pseudo-instructions for relocated i32_const * Make WasmTypeNode an ISymbolNode so it can be a reloc target

Checkpoint: Start wiring up relocs for call_indirect

ed20ac0

Copilot AI review requested due to automatic review settings February 10, 2026 00:09

kg added arch-wasm WebAssembly architecture area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI labels Feb 10, 2026

dotnet-policy-service Bot assigned kg Feb 10, 2026

Copilot started reviewing on behalf of kg February 10, 2026 00:10 View session

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Comment thread src/coreclr/jit/emitwasm.cpp Outdated

Comment thread src/coreclr/jit/emitwasm.cpp Outdated

Comment thread src/coreclr/jit/emitwasm.cpp Outdated

Checkpoint: We now reach 'Unsupported relocation type: R_WASM_TYPE_IN…

50e19c3

…DEX_LEB'

build-analysis Bot mentioned this pull request Feb 10, 2026

Test failure: baseservices/exceptions/stackoverflow/stackoverflowtester/stackoverflowtester.cmd #110173

Open

Add wasm enum values to RelocType

2e4e5ee

Copilot AI review requested due to automatic review settings February 10, 2026 17:19

Copilot started reviewing on behalf of kg February 10, 2026 17:20 View session

kg added 2 commits February 10, 2026 09:25

R2R runs to completion again

eef8857

jit-format

5f776b1

Copilot AI reviewed Feb 10, 2026

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Fix copy-paste error

6b57af5

Copilot AI review requested due to automatic review settings February 10, 2026 17:33

Copilot started reviewing on behalf of kg February 10, 2026 17:34 View session

Add reloc pseudo-instructions

9a41bd6

jakobbotsch reviewed Feb 10, 2026

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Comment thread src/coreclr/inc/corinfo.h Outdated

jit-format

1f321a9

Copilot AI reviewed Feb 10, 2026

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Comment thread src/coreclr/jit/emitwasm.cpp Outdated

kg marked this pull request as ready for review February 10, 2026 17:51

kg requested a review from MichalStrehovsky as a code owner February 10, 2026 17:51

Copilot AI review requested due to automatic review settings February 10, 2026 17:51

Copilot started reviewing on behalf of kg February 10, 2026 17:52 View session

Address PR feedback

c552071

kg added 4 commits February 11, 2026 12:08

Address PR feedback

b446a3d

Add ULEB/SLEB readers to DwarfHelper based on the ones from the PAL

3e1f0f6

Address PR feedback

f62df4b

Better name

79b1f15

Copilot AI review requested due to automatic review settings February 11, 2026 20:38

Copilot started reviewing on behalf of kg February 11, 2026 20:39 View session

Copilot AI reviewed Feb 11, 2026

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Comment thread src/coreclr/tools/Common/Compiler/DependencyAnalysis/Relocation.cs

Comment thread src/coreclr/jit/emitwasm.cpp

AndyAyersMS reviewed Feb 11, 2026

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Comment thread src/coreclr/jit/codegenwasm.cpp Outdated

Comment thread src/coreclr/jit/emitwasm.cpp

Comment thread src/coreclr/tools/Common/Compiler/DependencyAnalysis/Relocation.cs

kg added 4 commits February 11, 2026 14:09

Address PR feedback

8fd0398

Formatting

0984497

Add speculative implementations of padded ULEB/SLEB writer

1dc7b7d

Replace speculative implementations with ones from runtimelab

4d86a02

Copilot AI review requested due to automatic review settings February 11, 2026 23:55

Copilot started reviewing on behalf of kg February 11, 2026 23:56 View session

Copilot AI reviewed Feb 12, 2026

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Comment thread src/coreclr/jit/codegenwasm.cpp Outdated

Fix mistake caught by copilot

4c0c5b6

SingleAccretion approved these changes Feb 12, 2026

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Comment thread src/coreclr/jit/codegenwasm.cpp

Comment thread src/coreclr/tools/Common/Compiler/DependencyAnalysis/Relocation.cs Outdated

AndyAyersMS approved these changes Feb 13, 2026

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Address PR feedback

a1308b9

Copilot AI review requested due to automatic review settings February 13, 2026 02:34

Copilot AI reviewed Feb 13, 2026

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Comment thread src/coreclr/tools/Common/Compiler/ObjectWriter/Dwarf/DwarfHelper.cs

Comment thread src/coreclr/tools/Common/Compiler/ObjectWriter/Dwarf/DwarfHelper.cs

Comment thread src/coreclr/tools/Common/Compiler/ObjectWriter/Dwarf/DwarfHelper.cs

Comment thread src/coreclr/jit/emitwasm.cpp

kg enabled auto-merge (squash) February 13, 2026 03:42

kg merged commit 0efcb73 into dotnet:main Feb 13, 2026
130 of 132 checks passed

dotnet-maestro Bot mentioned this pull request Feb 14, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#4873

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kg commented Feb 10, 2026 •

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