[globalisel][tablegen] Add support for specific immediates in the match pattern

This enables a few rules such as ARM's uxtb instruction.

llvm-svn: 319457

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/utils/TableGen/GlobalISelEmitter.cpp b/llvm/utils/TableGen/GlobalISelEmitter.cpp
index f82b2fd3e9b..d9048c231c2 100644
--- a/llvm/utils/TableGen/GlobalISelEmitter.cpp
+++ b/llvm/utils/TableGen/GlobalISelEmitter.cpp
@@ -2812,6 +2812,14 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
     return failedImport("Dst pattern child isn't a leaf node or an MBB" + llvm::to_string(*DstChild));
   }
 
+  // It could be a specific immediate in which case we should just check for
+  // that immediate.
+  if (const IntInit *ChildIntInit =
+          dyn_cast<IntInit>(DstChild->getLeafValue())) {
+    DstMIBuilder.addRenderer<ImmRenderer>(ChildIntInit->getValue());
+    return InsertPt;
+  }
+
   // Otherwise, we're looking for a bog-standard RegisterClass operand.
   if (auto *ChildDefInit = dyn_cast<DefInit>(DstChild->getLeafValue())) {
     auto *ChildRec = ChildDefInit->getDef();