Remove unused functions from the xarch emitter#130803
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tannergooding merged 2 commits intoJul 18, 2026
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These functions all had zero call sites anywhere in the repo: - emitExtractRex2Prefix, AddRex2WPrefix, insKMaskBaseSize (declared, never defined) - AddVexPrefixIfNeeded, AddVexPrefixIfNeededAndNotPresent, AddSimdPrefixIfNeededAndNotPresent (unused inline prefix helpers) - emitIns_AI_R, emitIns_I_AI, emitIns_I_AX, emitIns_R_AX, emitIns_AX_R, emitIns_I_ARR, emitIns_I_ARX, emitIns_R_R_AR_I (unused instruction emitters) - IsAVXOnlyInstruction, emitIns_J_S Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
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Pull request overview
This PR removes a set of unused CoreCLR xarch emitter helpers/emitters from src/coreclr/jit/emitxarch.h and emitxarch.cpp, reducing dead code in the JIT emitter without intended behavioral changes.
Changes:
- Removed unused declarations and inline helpers from
emitxarch.h(prefix/encoding helpers and severalemitIns_*APIs). - Removed corresponding unused method implementations from
emitxarch.cpp(includingIsAVXOnlyInstructionand severalemitIns_*helpers). - Verified by repository-wide search that the removed symbols have no remaining references.
Show a summary per file
| File | Description |
|---|---|
| src/coreclr/jit/emitxarch.h | Deletes unused emitter APIs and inline prefix helpers from the xarch emitter header. |
| src/coreclr/jit/emitxarch.cpp | Deletes unused xarch emitter method implementations corresponding to the removed declarations. |
Copilot's findings
- Files reviewed: 2/2 changed files
- Comments generated: 0
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@dotnet/jit-contrib, @EgorBo More trivially dead code |
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Jul 15, 2026
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Jul 15, 2026
tannergooding
enabled auto-merge (squash)
July 15, 2026 21:00
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@EgorBo, needs re-approval due to resolving a merge conflict |
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Jul 16, 2026
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/ba-g unrelated timeouts |
tannergooding
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tannergooding-jit-remove-dead-xarch-emitter-fns
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July 18, 2026 16:43
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Removes 16 functions from the CoreCLR xarch emitter that had zero call sites anywhere in the repo. This is a DEBUG/encoding cleanup only -- no behavioral change.
Each function's declaration in
emitxarch.hand definition (with its doc-comment block) inemitxarch.cppwas removed, after re-verifying zero callers viagit grep -w <name> -- 'src/coreclr/*'.Removed:
emitExtractRex2Prefix,AddRex2WPrefix,insKMaskBaseSize(all declared but never defined);AddVexPrefixIfNeeded,AddVexPrefixIfNeededAndNotPresent,AddSimdPrefixIfNeededAndNotPresent(unused inline defs)emitIns_AI_R,emitIns_I_AI,emitIns_I_AX,emitIns_R_AX,emitIns_AX_R,emitIns_I_ARR,emitIns_I_ARX,emitIns_R_R_AR_IIsAVXOnlyInstruction,emitIns_J_SChecked for cascaded dead code after removal via a zero-caller scan over all emitxarch.h-declared method names -- no functions became newly dead as a result of these deletions; every helper the removed bodies called remains used elsewhere.
emitIns_IJwas found to be a pre-existing zero-caller function unrelated to this change, so it is intentionally left out of scope here.Build (
build.cmd clr.jit -c checked -a x64) succeeds with 0 warnings / 0 errors, and jit-format produces no changes.Note
This PR description and the changes were drafted with the assistance of GitHub Copilot.