[ThinLTO] Option to control path of distributed backend files

Summary:
Add support to control where files for a distributed backend (the
individual index files and optional imports files) are created.

This is invoked with a new thinlto-prefix-replace option in the gold
plugin and llvm-lto. If specified, expects a string of the form
"oldprefix:newprefix", and instead of generating these files in the
same directory path as the corresponding bitcode file, will use a path
formed by replacing the bitcode file's path prefix matching oldprefix
with newprefix.

Also add a new replace_path_prefix helper to Path.h in libSupport.

Depends on D19636.

Reviewers: joker.eph

Subscribers: llvm-commits, joker.eph

Differential Revision: http://reviews.llvm.org/D19644

llvm-svn: 269771

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index 70bbf2499ac..ad2267d596c 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -970,4 +970,29 @@ TEST(Support, RemoveDots) {
   EXPECT_EQ("c", Path1);
 #endif
 }
+
+TEST(Support, ReplacePathPrefix) {
+  SmallString<64> Path1("/foo");
+  SmallString<64> Path2("/old/foo");
+  SmallString<64> OldPrefix("/old");
+  SmallString<64> NewPrefix("/new");
+  SmallString<64> NewPrefix2("/longernew");
+  SmallString<64> EmptyPrefix("");
+
+  SmallString<64> Path = Path1;
+  path::replace_path_prefix(Path, OldPrefix, NewPrefix);
+  EXPECT_EQ(Path, "/foo");
+  Path = Path2;
+  path::replace_path_prefix(Path, OldPrefix, NewPrefix);
+  EXPECT_EQ(Path, "/new/foo");
+  Path = Path2;
+  path::replace_path_prefix(Path, OldPrefix, NewPrefix2);
+  EXPECT_EQ(Path, "/longernew/foo");
+  Path = Path1;
+  path::replace_path_prefix(Path, EmptyPrefix, NewPrefix);
+  EXPECT_EQ(Path, "/new/foo");
+  Path = Path2;
+  path::replace_path_prefix(Path, OldPrefix, EmptyPrefix);
+  EXPECT_EQ(Path, "/foo");
+}
 } // anonymous namespace