AMDGPU: Fix maximum instruction size for amdgcn

This was causing the conservative estimate of inline asm
size to be twice as big as expected.

llvm-svn: 272956
diff --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCAsmInfo.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCAsmInfo.cpp
index 4bc80a0..d7eb9f9 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCAsmInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUMCAsmInfo.cpp
@@ -9,12 +9,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "AMDGPUMCAsmInfo.h"
+#include "llvm/ADT/Triple.h"
 
 using namespace llvm;
+
 AMDGPUMCAsmInfo::AMDGPUMCAsmInfo(const Triple &TT) : MCAsmInfoELF() {
   HasSingleParameterDotFile = false;
   //===------------------------------------------------------------------===//
-  MaxInstLength = 16;
+  MaxInstLength = (TT.getArch() == Triple::amdgcn) ? 8 : 16;
   SeparatorString = "\n";
   CommentString = ";";
   PrivateLabelPrefix = "";