[SILProfiler] Do not set up a profiler for a function twice

rdar://58861159

Author: vedantk

lib/SILGen/SILGen.cpp

@@ -551,7 +551,7 @@ static bool haveProfiledAssociatedFunction(SILDeclRef constant) {
 /// Set up the function for profiling instrumentation.
 static void setUpForProfiling(SILDeclRef constant, SILFunction *F,
                               ForDefinition_t forDefinition) {
-  if (!forDefinition)
+  if (!forDefinition || F->getProfiler())
     return;
 
   ASTNode profiledNode;

test/Profiler/coverage_struct.swift

@@ -0,0 +1,11 @@
+// RUN: %target-swift-frontend -Xllvm -sil-full-demangle -profile-generate -profile-coverage-mapping -emit-sorted-sil -emit-sil -module-name coverage_struct %s | %FileCheck %s
+
+struct Foo {
+  var a = false
+
+// CHECK: sil_coverage_map {{.*}}// variable initialization expression of coverage_struct.Foo.b : Swift.Bool
+// CHECK-NEXT: [[@LINE+1]]:11 -> [[@LINE+3]]:6 : 0
+  let b = {
+    false
+  }()
+}