[sil][debug-info] Add 'const' to maybeScopeless 'SILInstruction &' argument.

This function only uses the reference in a const way, so nothing changes
functionally, we can just pass it into contexts where we have a const
reference without fighting the compiler.

Author: gottesmm

include/swift/SIL/SILDebugScope.h

@@ -95,7 +95,7 @@ class SILDebugScope : public SILAllocated<SILDebugScope> {
 };
 
 /// Determine whether an instruction may not have a SILDebugScope.
-bool maybeScopeless(SILInstruction &I);
+bool maybeScopeless(const SILInstruction &inst);
 
 /// Knows how to make a deep copy of a debug scope.
 class ScopeCloner {

lib/SIL/IR/SILDebugScope.cpp

@@ -57,8 +57,8 @@ SILFunction *SILDebugScope::getParentFunction() const {
 }
 
 /// Determine whether an instruction may not have a SILDebugScope.
-bool swift::maybeScopeless(SILInstruction &I) {
-  if (I.getFunction()->isBare())
+bool swift::maybeScopeless(const SILInstruction &inst) {
+  if (inst.getFunction()->isBare())
     return true;
-  return !isa<DebugValueInst>(I) && !isa<DebugValueAddrInst>(I);
+  return !isa<DebugValueInst>(inst) && !isa<DebugValueAddrInst>(inst);
 }