Fix td file for OpMerge + OpBranch instructions

All OpBranch should be marked as IsBarrier so MIR knows it can
be used as the last instruction of a BB, and Op*Merge operands should
be marked as "unknown" as the backend transforms those to spirv labels,
which meaning the MIR verified doesn't interpret as BB labels.

Signed-off-by: Nathan Gauër <[email protected]>

Author: Keenuts

llvm/lib/Target/SPIRV/SPIRVInstrInfo.td

@@ -617,15 +617,13 @@ def OpFwidthCoarse: UnOp<"OpFwidthCoarse", 215>;
 
 def OpPhi: Op<245, (outs ID:$res), (ins TYPE:$type, ID:$var0, ID:$block0, variable_ops),
                   "$res = OpPhi $type $var0 $block0">;
-def OpLoopMerge: Op<246, (outs), (ins ID:$merge, ID:$continue, LoopControl:$lc, variable_ops),
+def OpLoopMerge: Op<246, (outs), (ins unknown:$merge, unknown:$continue, LoopControl:$lc, variable_ops),
                   "OpLoopMerge $merge $continue $lc">;
-def OpSelectionMerge: Op<247, (outs), (ins ID:$merge, SelectionControl:$sc),
+def OpSelectionMerge: Op<247, (outs), (ins unknown:$merge, SelectionControl:$sc),
                   "OpSelectionMerge $merge $sc">;
 def OpLabel: Op<248, (outs ID:$label), (ins), "$label = OpLabel">;
 let isBarrier = 1, isTerminator=1 in {
   def OpBranch: Op<249, (outs), (ins unknown:$label), "OpBranch $label">;
-}
-let isTerminator=1 in {
   def OpBranchConditional: Op<250, (outs), (ins ID:$cond, unknown:$true, unknown:$false, variable_ops),
                   "OpBranchConditional $cond $true $false">;
   def OpSwitch: Op<251, (outs), (ins ID:$sel, ID:$dflt, variable_ops), "OpSwitch $sel $dflt">;