Emit prefix data after debug and EH directives.

This ensures that the prefix data is treated as part of the function for
the purpose of debug info.  This provides a better debugging experience,
among other things by allowing a debug info client to correctly look up
a function in debug info given a function pointer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193042 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -462,10 +462,6 @@ void AsmPrinter::EmitFunctionHeader() {
     OutStreamer.EmitLabel(DeadBlockSyms[i]);
   }
 
-  // Emit the prefix data.
-  if (F->hasPrefixData())
-    EmitGlobalConstant(F->getPrefixData());
-
   // Emit pre-function debug and/or EH information.
   if (DE) {
     NamedRegionTimer T(EHTimerName, DWARFGroupName, TimePassesIsEnabled);
@@ -475,6 +471,10 @@ void AsmPrinter::EmitFunctionHeader() {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
     DD->beginFunction(MF);
   }
+
+  // Emit the prefix data.
+  if (F->hasPrefixData())
+    EmitGlobalConstant(F->getPrefixData());
 }
 
 /// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the

test/CodeGen/X86/prefixdata.ll

@@ -3,12 +3,14 @@
 @i = linkonce_odr global i32 1
 
 ; CHECK: f:
+; CHECK-NEXT: .cfi_startproc
 ; CHECK-NEXT: .long	1
 define void @f() prefix i32 1 {
   ret void
 }
 
 ; CHECK: g:
+; CHECK-NEXT: .cfi_startproc
 ; CHECK-NEXT: .quad	i
 define void @g() prefix i32* @i {
   ret void