Stream: git-wasmtime

Topic: wasmtime / Issue #1152 Legalization with isplit as last i...

Wasmtime GitHub notifications bot (Apr 28 2020 at 14:40):

whitequark commented on Issue #1152:

This legalization is added in #1616, using an intermediate copy.

Wasmtime GitHub notifications bot (Feb 03 2021 at 18:24):

bjorn3 commented on Issue #1152:

The new backend framework doesn't use legalizations as much as the old backend framework anymore.

Wasmtime GitHub notifications bot (Feb 03 2021 at 18:24):

bjorn3 closed Issue #1152:

• What are the steps to reproduce the issue? Can you include a CLIF test case,
  ideally reduced with the bugpoint clif-util command?

  1. Add the following as legalization:

  rust for &(ty, ty_half) in &[(I64, I32), (I128, I64)] { let inst = ireduce.bind(ty_half).bind(ty); expand.legalize( def!(a = inst(x)), vec![ def!((a, xh) = isplit(x)), ] ) }

  2. Try to compile:

  ```
  test run
  target x86_64

  function u0:0() -> i64 system_v {
  ebb0:
  v0 = iconst.i64 0
  v2 = iconcat v0, v0
  v3 = ireduce.i64 v2
  return v3
  }
  ; run
  ```

• What do you expect to happen? What does actually happen? Does it panic, and
  if so, with which assertion?

  I expected the ireduce to be legalized to v3, v999 = isplit v2. The result however was a verifier error:

  ```
  function u0:0() -> i64 [%rax] system_v {
  ebb0:
  [RexOp1pu_id#b8] v0 = iconst.i64 0
  [-] v2 = iconcat v0, v0
  [Op1ret#c3] return v3
  ;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ; error: inst3: v3 is defined by inst2 which has no EBB

  }
  ```

  The problem is that the following legalization code is generated:

  rust pos.func.dfg.clear_results(inst); let curpos = pos.position(); let srcloc = pos.srcloc(); let (a, xh) = split::isplit(pos.func, cfg, curpos, srcloc, x); let removed = pos.remove_inst(); debug_assert_eq!(removed, inst); return true;

  The inst results are never attached to an instruction again, nor turned into aliases.

• Which Cranelift version / commit hash / branch are you using? master
  

Last updated: Dec 23 2024 at 12:05 UTC