tests: add an end-to-end test to check that the compiler generates optimal code for static String constants.

Author: eeckstein

test/SILOptimizer/static_strings.swift

@@ -0,0 +1,107 @@
+// RUN: %target-swift-frontend -O -emit-ir  %s | %FileCheck %s
+// RUN: %target-swift-frontend -Osize -emit-ir  %s | %FileCheck %s
+
+// RUN: %empty-directory(%t) 
+// RUN: %target-build-swift -O -module-name=test %s -o %t/a.out
+// RUN: %target-run %t/a.out | %FileCheck %s -check-prefix=CHECK-OUTPUT
+
+// REQUIRES: executable_test,swift_stdlib_no_asserts,optimized_stdlib
+// REQUIRES: CPU=arm64 || CPU=x86_64
+
+// This is an end-to-end test to ensure that the optimizer generates
+// optimal code for static String variables.
+
+public struct S {
+  // CHECK: {{^@"}}[[SMALL:.*smallstr.*pZ]]" ={{.*}} global {{.*}} inttoptr
+  public static let smallstr = "abc123a"
+  // CHECK: {{^@"}}[[LARGE:.*largestr.*pZ]]" ={{.*}} global {{.*}} inttoptr {{.*}} add
+  public static let largestr = "abc123asd3sdj3basfasdf"
+  // CHECK: {{^@"}}[[UNICODE:.*unicodestr.*pZ]]" ={{.*}} global {{.*}} inttoptr {{.*}} add
+  public static let unicodestr = "❄️gastroperiodyni"
+}
+
+// unsafeMutableAddressor for S.smallstr
+// CHECK: define {{.*smallstr.*}}u"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}} @"[[SMALL]]"
+// CHECK-NEXT: }
+
+// getter for S.smallstr
+// CHECK: define {{.*smallstr.*}}gZ"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+
+// unsafeMutableAddressor for S.largestr
+// CHECK: define {{.*largestr.*}}u"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}} @"[[LARGE]]"
+// CHECK-NEXT: }
+
+// getter for S.largestr
+// CHECK: define {{.*largestr.*}}gZ"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+
+// unsafeMutableAddressor for S.unicodestr
+// CHECK: define {{.*unicodestr.*}}u"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}} @"[[UNICODE]]"
+// CHECK-NEXT: }
+
+// getter for S.unicodestr
+// CHECK: define {{.*unicodestr.*}}gZ"
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+
+// CHECK-LABEL: define {{.*}}get_smallstr
+// CHECK:      entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+@inline(never)
+public func get_smallstr() -> String {
+  return S.smallstr
+}
+
+// CHECK-LABEL: define {{.*}}get_largestr
+// CHECK:      entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+@inline(never)
+public func get_largestr() -> String {
+  return S.largestr
+}
+
+// CHECK-LABEL: define {{.*}}get_unicodestr
+// CHECK:      entry:
+// CHECK-NEXT:   ret {{.*}}
+// CHECK-NEXT: }
+@inline(never)
+public func get_unicodestr() -> String {
+  return S.unicodestr
+}
+
+// Also check if the generated code is correct.
+
+// CHECK-OUTPUT: abc123a
+// CHECK-OUTPUT: abc123asd3sdj3basfasdf
+// CHECK-OUTPUT: ❄️gastroperiodyni
+print(get_smallstr())
+print(get_largestr())
+print(get_unicodestr())
+
+// Really load the globals from their addresses.
+@_optimize(none)
+func print_strings_from_addressors() {
+  print(S.smallstr)
+  print(S.largestr)
+  print(S.unicodestr)
+}
+
+// CHECK-OUTPUT: abc123a
+// CHECK-OUTPUT: abc123asd3sdj3basfasdf
+// CHECK-OUTPUT: ❄️gastroperiodyni
+print_strings_from_addressors()
+