Assertions: display the assertion help hint only once and after the assertion message

It's more readable if the first thing which is printed is the actual assertion message

Author: eeckstein

lib/Basic/Assertions.cpp

@@ -37,13 +37,6 @@ int CONDITIONAL_ASSERT_Global_enable_flag =
 #endif
 
 void ASSERT_failure(const char *expr, const char *filename, int line, const char *func) {
-  if (AssertHelp) {
-    ASSERT_help();
-  } else {
-    llvm::errs() << "Assertion help:  -Xllvm -assert-help\n";
-  }
-
-
   // Format here matches that used by `assert` on macOS:
   llvm::errs()
     << "Assertion failed: "
@@ -52,6 +45,8 @@ void ASSERT_failure(const char *expr, const char *filename, int line, const char
     << filename << ":"
     << line << ".\n";
 
+  ASSERT_help();
+
   if (AssertContinue) {
     llvm::errs() << "Continuing after failed assertion (-Xllvm -assert-continue)\n";
     return;
@@ -67,6 +62,11 @@ void ASSERT_help() {
   }
   ASSERT_help_shown = 1;
 
+  if (!AssertHelp) {
+    llvm::errs() << "(to display assertion configuration options: -Xllvm -assert-help)\n";
+    return;
+  }
+
   llvm::errs() << "\n";
   llvm::errs() << "Control assertion behavior with one or more of the following options:\n\n";
   llvm::errs() << " -Xllvm -assert-continue\n";