[Mlir-commits] [mlir] [mlir] Avoid verifying live user in conversion diagnostic (PR #210566)

[llvmlistbot at llvm.org]

qyingwu wrote:

@matthias-springer @joker-eph 
Thanks! I dug further and I think you were right that the fix belongs in the verifier.
The crash happens while reporting the unresolved materialization diagnostic, but the actual bad dereference is in the SPIR-V verifier:
  ```text
  legalizeUnresolvedMaterialization
    -> Diagnostic::operator<<(Operation *)
    -> Operation::print
    -> AsmState::AsmState
    -> verifyOpAndAdjustFlags
    -> mlir::verify
    -> spirv::FuncOp::verifyBody
    -> retOp.getValue().getType()
  ```

The relevant backtrace frames are:
frame #3  mlir::detail::ValueImpl::getType(this=0x0)
frame #4  mlir::Value::getType()
frame #5  mlir::spirv::FuncOp::verifyBody() at SPIRVOps.cpp:1229
frame #30 verifyOpAndAdjustFlags at AsmPrinter.cpp:2113
frame #34 mlir::Diagnostic::appendOp
frame #37 legalizeUnresolvedMaterialization at DialectConversion.cpp:3395
frame #38 mlir::OperationConverter::applyConversion

So the failed conversion leaves a malformed spirv.ReturnValue with a missing/null operand, and diagnostic printing triggers verification of that IR. The patch now makes spirv::FuncOp::verifyBody() diagnose the missing return value before reading its type, and removes the dialect-conversion printing workaround.

I also reran:
  `build/bin/llvm-lit -v mlir/test/Transforms/test-legalize-erased-op-with-uses.mlir`

It passes after the current fix.

https://github.com/llvm/llvm-project/pull/210566