From 3b895cfac99babcf0e4fe80af1c70e11760abb77 Mon Sep 17 00:00:00 2001
From: Dale Johannesen <dalej@apple.com>
Date: Tue, 12 May 2009 22:32:29 +0000
Subject: [PATCH] Slightly improve generated code in a degenerate case. Should
 remove a warning from MSVC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71603 91177308-0d34-0410-b5e6-96231b3b80d8
---
 utils/TableGen/DAGISelEmitter.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/utils/TableGen/DAGISelEmitter.cpp b/utils/TableGen/DAGISelEmitter.cpp
index 39791e2cba5..0e2e61596f6 100644
--- a/utils/TableGen/DAGISelEmitter.cpp
+++ b/utils/TableGen/DAGISelEmitter.cpp
@@ -2025,6 +2025,14 @@ void DAGISelEmitter::EmitInstructionSelector(std::ostream &OS) {
       OpcodeVTMap.find(OpName);
     std::vector<std::string> &OpVTs = OpVTI->second;
     OS << "  case " << OpName << ": {\n";
+    // If we have only one variant and it's the default, elide the
+    // switch.  Marginally faster, and makes MSVC happier.
+    if (OpVTs.size()==1 && OpVTs[0].empty()) {
+      OS << "    return Select_" << getLegalCName(OpName) << "(N);\n";
+      OS << "    break;\n";
+      OS << "  }\n";
+      continue;
+    }
     // Keep track of whether we see a pattern that has an iPtr result.
     bool HasPtrPattern = false;
     bool HasDefaultPattern = false;