Fix assembling of xchg %eax, %eax to not use the NOP encoding of 0x90. This was done by creating a new register group that excludes AX registers. Fixes PR10345. Also added aliases for flipping the order of the operands of xchg <reg>, %eax.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141274 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/EDEmitter.cpp b/utils/TableGen/EDEmitter.cpp
index 85f7e1f..b5fe7e6 100644
--- a/utils/TableGen/EDEmitter.cpp
+++ b/utils/TableGen/EDEmitter.cpp
@@ -256,12 +256,15 @@
   REG("GR8");
   REG("GR8_NOREX");
   REG("GR16");
+  REG("GR16_NOAX");
   REG("GR32");
+  REG("GR32_NOAX");
   REG("GR32_NOREX");
   REG("GR32_TC");
   REG("FR32");
   REG("RFP32");
   REG("GR64");
+  REG("GR64_NOAX");
   REG("GR64_TC");
   REG("FR64");
   REG("VR64");