From dae2ef47f1e40762bbb8bb6dc2ff5f2409e2d68e Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Thu, 21 Nov 2013 01:08:53 +0000
Subject: [PATCH] [PECOFF] Move files with ".lib" extension to the end of the
 input file list.

It's allowed to specify library files *before* object files in the command
line. Object files seems to be processed first, and then their undefined
symbols are resolved from the libraries. This patch implements the compatible
behavior.

llvm-svn: 195295
---
 lld/lib/Driver/WinLinkDriver.cpp                | 17 +++++++++++++++--
 lld/unittests/DriverTests/WinLinkDriverTest.cpp | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/lld/lib/Driver/WinLinkDriver.cpp b/lld/lib/Driver/WinLinkDriver.cpp
index 7f71a3c97b9f..7e9a55cfcbd7 100644
--- a/lld/lib/Driver/WinLinkDriver.cpp
+++ b/lld/lib/Driver/WinLinkDriver.cpp
@@ -13,6 +13,7 @@
 ///
 //===----------------------------------------------------------------------===//
 
+#include <algorithm>
 #include <cctype>
 #include <sstream>
 #include <map>
@@ -600,6 +601,8 @@ WinLinkDriver::parse(int argc, const char *argv[], PECOFFLinkingContext &ctx,
     defaultLibs.push_back((*it)->getValue());
   }
 
+  std::vector<StringRef> inputFiles;
+
   // Process all the arguments and create Input Elements
   for (auto inputArg : *parsedArgs) {
     switch (inputArg->getOption().getID()) {
@@ -850,8 +853,7 @@ WinLinkDriver::parse(int argc, const char *argv[], PECOFFLinkingContext &ctx,
       break;
 
     case OPT_INPUT:
-      inputElements.push_back(std::unique_ptr<InputElement>(
-          new PECOFFFileNode(ctx, ctx.allocate(inputArg->getValue()))));
+      inputFiles.push_back(ctx.allocate(inputArg->getValue()));
       break;
 
 #define DEFINE_BOOLEAN_FLAG(name, setter)       \
@@ -877,6 +879,17 @@ WinLinkDriver::parse(int argc, const char *argv[], PECOFFLinkingContext &ctx,
     }
   }
 
+  // Move files with ".lib" extension at the end of the input file list. Say
+  // foo.obj depends on bar.lib. The linker needs to accept both "bar.lib
+  // foo.obj" and "foo.obj bar.lib".
+  auto compfn = [](StringRef a, StringRef b) {
+    return !a.endswith_lower(".lib") && b.endswith_lower(".lib");
+  };
+  std::stable_sort(inputFiles.begin(), inputFiles.end(), compfn);
+  for (StringRef path : inputFiles)
+    inputElements.push_back(std::unique_ptr<InputElement>(
+        new PECOFFFileNode(ctx, path)));
+
   // Use the default entry name if /entry option is not given.
   if (ctx.entrySymbolName().empty())
     ctx.setEntrySymbolName(getDefaultEntrySymbolName(ctx));
diff --git a/lld/unittests/DriverTests/WinLinkDriverTest.cpp b/lld/unittests/DriverTests/WinLinkDriverTest.cpp
index 65f2a9c3161f..89a590fbd914 100644
--- a/lld/unittests/DriverTests/WinLinkDriverTest.cpp
+++ b/lld/unittests/DriverTests/WinLinkDriverTest.cpp
@@ -130,6 +130,21 @@ TEST_F(WinLinkParserTest, Libpath) {
   EXPECT_EQ("dir2", paths[1]);
 }
 
+//
+// Tests for input file order
+//
+
+TEST_F(WinLinkParserTest, InputOrder) {
+  EXPECT_TRUE(parse("link.exe", "b.lib", "b.obj", "c.obj", "a.lib", "a.obj",
+                    nullptr));
+  EXPECT_EQ(5, inputFileCount());
+  EXPECT_EQ("b.obj", inputFile(0));
+  EXPECT_EQ("c.obj", inputFile(1));
+  EXPECT_EQ("a.obj", inputFile(2));
+  EXPECT_EQ("b.lib", inputFile(3));
+  EXPECT_EQ("a.lib", inputFile(4));
+}
+
 //
 // Tests for command line options that take values.
 //