[all-commits] [llvm/llvm-project] 4a7525: [LoongArch] Fix invalid VEXTH combines for unsuppo...

[hev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 4a75259134c72d8be7fa3ea36c9dc7bfc02640ac
      https://github.com/llvm/llvm-project/commit/4a75259134c72d8be7fa3ea36c9dc7bfc02640ac
  Author: hev <wangrui at loongson.cn>
  Date:   2026-07-17 (Fri, 17 Jul 2026)

  Changed paths:
    M llvm/lib/Target/LoongArch/LoongArchISelLowering.cpp
    A llvm/test/CodeGen/LoongArch/lasx/issue207316.ll
    M llvm/test/CodeGen/LoongArch/lasx/xvexth.ll
    M llvm/test/CodeGen/LoongArch/lsx/vexth.ll

  Log Message:
  -----------
  [LoongArch] Fix invalid VEXTH combines for unsupported type extensions (#209725)

`performEXTENDCombine` could form `VEXTH`/`VEXTH_U` nodes for
unsupported type combinations, such as extending `v8i8` to `v8i32` or
`v2i64` to `v2i128`. These illegal nodes would later reach instruction
selection and trigger backend failures:

* `Cannot select: LoongArchISD::VEXTH`
* `Don't know how to legalize this operation`

Prevent these combines from firing by verifying that the destination
type is legal and has exactly twice the total bit width of the source
before forming a `VEXTH`/`VEXTH_U` node.
    
Apply the same checks to `performSHLCombine` for consistency.


Fixes
https://github.com/llvm/llvm-project/pull/207316#issuecomment-4978234865
Fixes
https://github.com/llvm/llvm-project/pull/207316#issuecomment-4979233899



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