From c2b8d6ac6588067f720df48ae89d86045a62101f Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Tue, 29 Mar 2011 20:27:38 +0000
Subject: [PATCH] Check early if this is an unsupported opcode, so that we can
 avoid needlessly instantiating the base register in some cases.

llvm-svn: 128481
---
 lib/Target/ARM/ARMLoadStoreOptimizer.cpp | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
index 0dab835f7c8..838f20f4b77 100644
--- a/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
+++ b/lib/Target/ARM/ARMLoadStoreOptimizer.cpp
@@ -308,6 +308,10 @@ ARMLoadStoreOpt::MergeOps(MachineBasicBlock &MBB,
     // VLDM/VSTM do not support DB mode without also updating the base reg.
     Mode = ARM_AM::db;
   else if (Offset != 0) {
+    // Check if this is a supported opcode before we insert instructions to
+    // calculate a new base register.
+    if (!getLoadStoreMultipleOpcode(Opcode, Mode)) return false;
+
     // If starting offset isn't zero, insert a MI to materialize a new base.
     // But only do so if it is cost effective, i.e. merging more than two
     // loads / stores.