Include #file -> #filePath table in printed SIL

A proof of concept for tools providing this information in more useful forms.

Author: beccadax

lib/SIL/SILPrinter.cpp

@@ -47,6 +47,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/FileSystem.h"
+#include <set>
 
 
 using namespace swift;
@@ -2750,6 +2751,57 @@ printSILCoverageMaps(SILPrintContext &Ctx,
     M->print(Ctx);
 }
 
+using MagicFileStringMap =
+    llvm::StringMap<std::pair<std::string, /*isWinner=*/bool>>;
+
+static void
+printMagicFileStringMapEntry(SILPrintContext &Ctx,
+                             const MagicFileStringMap::MapEntryTy &entry) {
+  auto &OS = Ctx.OS();
+  OS << "//   '" << std::get<0>(entry.second)
+     << "' => '" << entry.first() << "'";
+
+  if (!std::get<1>(entry.second))
+    OS << " (alternate)";
+
+  OS << "\n";
+}
+
+static void printMagicFileStringMap(SILPrintContext &Ctx,
+                                    const MagicFileStringMap map) {
+  if (map.empty())
+    return;
+
+  Ctx.OS() << "\n\n// Mappings from '#file' to '#filePath':\n";
+
+  if (Ctx.sortSIL()) {
+    llvm::SmallVector<llvm::StringRef, 16> keys;
+    llvm::copy(map.keys(), std::back_inserter(keys));
+
+    llvm::sort(keys, [&](StringRef leftKey, StringRef rightKey) -> bool {
+      const auto &leftValue = map.find(leftKey)->second;
+      const auto &rightValue = map.find(rightKey)->second;
+
+      // Lexicographically earlier #file strings sort earlier.
+      if (std::get<0>(leftValue) != std::get<0>(rightValue))
+        return std::get<0>(leftValue) < std::get<0>(rightValue);
+
+      // Conflict winners sort before losers.
+      if (std::get<1>(leftValue) != std::get<1>(rightValue))
+        return std::get<1>(leftValue);
+
+      // Finally, lexicographically earlier #filePath strings sort earlier.
+      return leftKey < rightKey;
+    });
+
+    for (auto key : keys)
+      printMagicFileStringMapEntry(Ctx, *map.find(key));
+  } else {
+    for (const auto &entry : map)
+      printMagicFileStringMapEntry(Ctx, entry);
+  }
+}
+
 void SILProperty::print(SILPrintContext &Ctx) const {
   PrintOptions Options = PrintOptions::printSIL();
 
@@ -2864,6 +2916,10 @@ void SILModule::print(SILPrintContext &PrintCtx, ModuleDecl *M,
   printSILProperties(PrintCtx, getPropertyList());
   printExternallyVisibleDecls(PrintCtx, externallyVisible.getArrayRef());
 
+  if (M)
+    printMagicFileStringMap(
+        PrintCtx, M->computeMagicFileStringMap());
+
   OS << "\n\n";
 }
 

test/SILGen/magic_identifier_file.swift

@@ -31,3 +31,7 @@ func forceTry(_ fn: () throws -> ()) {
 // ABSOLUTE: string_literal utf8 "SOURCE_DIR/test/SILGen/magic_identifier_file.swift"
 // CONCISE: string_literal utf8 "Foo/magic_identifier_file.swift"
 }
+
+// CONCISE-LABEL: // Mappings from '#file' to '#filePath':
+// CONCISE:       //   'Foo/magic_identifier_file.swift' => 'SOURCE_DIR/test/SILGen/magic_identifier_file.swift'
+