[PATCH] D142834: [X86][MC][bugfix] Report error for mismatched modifier in inline asm and remove function getX86SubSuperRegisterOrZero

[Phoebe Wang via Phabricator via llvm-commits]

pengfei added inline comments.


================
Comment at: llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp:748
   switch (Size) {
   default: return X86::NoRegister;
   case 8:
----------------
skan wrote:
> pengfei wrote:
> > skan wrote:
> > > skan wrote:
> > > > craig.topper wrote:
> > > > > Why do we allow invalid sizes?
> > > > I think the previous author was overly conservative here. Let's use a `llvm_unreachable` here.
> > > > Why do we allow invalid sizes?
> > > 
> > > The test  `CodeGen/X86/asm-reject-reg-type-mismatch.ll` will fail if we use `llvm_unreachable` here.
> > > 
> > > ```
> > > ; CHECK: error: couldn't allocate output register for constraint '{ax}'
> > > define i128 @blup() {
> > >   %v = tail call i128 asm "", "={ax},0"(i128 0)
> > >   ret i128 %v
> > > }
> > > ```
> > > 
> > > See more details here https://reviews.llvm.org/D10813 
> > Is it caused by error message not match?
> > Is it caused by error message not match?
> 
> It is caused by the crash due to the `llvm_unreachable` at line 748.
> 
> ```
> UNREACHABLE executed at llvm-project/llvm/lib/Target/X86/MCTargetDesc/X86MCTargetDesc.cpp:748!
> 
> ```
> `getX86SubSuperRegister` is called with `Size`  128, and an inline asm error is emitted in `SelectionDAGBuilder.cpp` when the returned register is not valid.
> If we used "llvm_unreachable" at line 748, the llc would crash before emitting an error.
> 
> 
Will it be solved by adding `--crash` after `not`?


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142834/new/

https://reviews.llvm.org/D142834