Don't emit the FORCE_LOAD symbols when the compiler is running

on behalf of the debugger.  The debugger will read the LinkLibrary's
from all the modules it sees, and hand load all the required dependencies,
and since the symbol is weak it doesn't even tell us whether a
required dependency is missing. So it serves no purpose in this case.

<rdar://problem/51463642>

Author: jimingham

lib/IRGen/IRGenModule.cpp

@@ -1033,7 +1033,12 @@ void IRGenModule::addLinkLibrary(const LinkLibrary &linkLib) {
   }
   }
 
-  if (linkLib.shouldForceLoad()) {
+  // Don't emit the FORCE_LOAD symbols when the compiler is running
+  // on behalf of the debugger.  The debugger will read the LinkLibrary's
+  // from all the modules it sees, and hand load all the required dependencies,
+  // and since the symbol is weak it doesn't even tell us whether a
+  // required dependency is missing. So it serves no purpose in this case.
+  if (linkLib.shouldForceLoad() && !Context.LangOpts.DebuggerSupport) {
     llvm::SmallString<64> buf;
     encodeForceLoadSymbolName(buf, linkLib.getName());
     auto ForceImportThunk =

test/Serialization/autolinking.swift

@@ -15,6 +15,10 @@
 // RUN: %FileCheck %s < %t/force-load.txt
 // RUN: %FileCheck -check-prefix FORCE-LOAD-CLIENT -check-prefix FORCE-LOAD-CLIENT-%target-object-format %s < %t/force-load.txt
 
+// RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -debugger-support -lmagic %s -I %t > %t/force-load.txt
+// RUN: %FileCheck %s < %t/force-load.txt
+// RUN: %FileCheck -check-prefix NO-FORCE-LOAD-CLIENT %s < %t/force-load.txt
+
 // RUN: %target-swift-frontend -disable-autolinking-runtime-compatibility-dynamic-replacements -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name module %S/../Inputs/empty.swift | %FileCheck --check-prefix=NO-FORCE-LOAD %s
 // RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name module %S/../Inputs/empty.swift -autolink-force-load | %FileCheck --check-prefix=FORCE-LOAD %s
 // RUN: %target-swift-frontend -runtime-compatibility-version none -emit-ir -parse-stdlib -module-name someModule -module-link-name 0module %S/../Inputs/empty.swift -autolink-force-load | %FileCheck --check-prefix=FORCE-LOAD-HEX %s
@@ -42,6 +46,7 @@ import someModule
 // FORCE-LOAD-HEX:   ret void
 // FORCE-LOAD-HEX: }
 
+// NO-FORCE-LOAD-CLIENT-NOT: FORCE_LOAD
 // FORCE-LOAD-CLIENT: @"_swift_FORCE_LOAD_$_module_$_autolinking" = weak_odr hidden constant void ()* @"_swift_FORCE_LOAD_$_module"
 // FORCE-LOAD-CLIENT: @llvm.used = appending global [{{[0-9]+}} x i8*] [
 // FORCE-LOAD-CLIENT: i8* bitcast (void ()** @"_swift_FORCE_LOAD_$_module_$_autolinking" to i8*)