WIP: AMDGPU: Use MFPropsModifier modifier in SIFoldOperands

This doesn't appear to work. I do not get an error in the new PM.

Author: arsenm

llvm/lib/Target/AMDGPU/SIFoldOperands.cpp

@@ -2334,6 +2334,8 @@ bool SIFoldOperandsImpl::tryOptimizeAGPRPhis(MachineBasicBlock &MBB) {
 }
 
 bool SIFoldOperandsImpl::run(MachineFunction &MF) {
+  MFPropsModifier _(*this, MF);
+
   MRI = &MF.getRegInfo();
   ST = &MF.getSubtarget<GCNSubtarget>();
   TII = ST->getInstrInfo();

llvm/test/CodeGen/AMDGPU/si-fold-operands-requires-ssa.mir

@@ -0,0 +1,15 @@
+# RUN: not --crash llc -mtriple=amdgcn -mcpu=gfx900 -run-pass=si-fold-operands -filetype=null %s 2>&1 | FileCheck -check-prefix=ERR %s
+# RUN: not --crash llc -mtriple=amdgcn -mcpu=gfx900 -passes=si-fold-operands -filetype=null %s 2>&1 | FileCheck -check-prefix=ERR %s
+
+# ERR: MachineFunctionProperties required by SI Fold Operands pass are not met by function not_ssa.
+# ERR-NEXT: Required properties: IsSSA
+# ERR-NEXT: Current properties: NoPHIs
+---
+name:            not_ssa
+body:             |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+    %0:vgpr_32 = COPY $vgpr0
+    %0:vgpr_32 = COPY $vgpr1
+
+...