[PATCH] D22722: MIRParser/MIRPrinter: Compute isSSA instead of printing/parsing it.

[Matthias Braun via llvm-commits]

MatzeB added inline comments.

================
Comment at: lib/CodeGen/MIRParser/MIRParser.cpp:303
@@ +302,3 @@
+    if (!MRI.hasOneDef(Reg) && !MRI.def_empty(Reg)) {
+      IsSSA = false;
+      break;
----------------
kparzysz wrote:
> This check is insufficient.  The def must dominate all uses.  It is possible to have a non-SSA program where all registers have single definitions, but where a use is not dominated by the def.
While true in general, in llvm machine functions we can never have a virtual register use without any dominating definition (you need to place an IMPLICIT_DEF if you do not have a real definition).
I don't think we need to cater for malformed .mir here. The MachineVerifier step performed after reading should catch that case.


Repository:
  rL LLVM

https://reviews.llvm.org/D22722