Support, LTO: When pruning a directory, ignore files matching a prefix.
This is a safeguard against data loss if the user specifies a directory
that is not a cache directory. Teach the existing cache pruning clients
to create files with appropriate names.
Differential Revision: https://reviews.llvm.org/D31109
llvm-svn: 298271
diff --git a/lld/test/ELF/lto/cache.ll b/lld/test/ELF/lto/cache.ll
index deb11b6..55e3a3d 100644
--- a/lld/test/ELF/lto/cache.ll
+++ b/lld/test/ELF/lto/cache.ll
@@ -4,12 +4,13 @@
; RUN: opt -module-hash -module-summary %p/Inputs/cache.ll -o %t2.o
; RUN: rm -Rf %t.cache && mkdir %t.cache
-; Create a file that will be removed by cache pruning due to age.
-; RUN: touch -t 197001011200 %t.cache/foo
+; Create two files that would be removed by cache pruning due to age.
+; We should only remove files matching the pattern "llvmcache-*".
+; RUN: touch -t 197001011200 %t.cache/llvmcache-foo %t.cache/foo
; RUN: ld.lld --thinlto-cache-dir=%t.cache --thinlto-cache-policy prune_after=1h -o %t3 %t2.o %t.o
-; Two cached objects, plus a timestamp file, minus the file we removed.
-; RUN: ls %t.cache | count 3
+; Two cached objects, plus a timestamp file and "foo", minus the file we removed.
+; RUN: ls %t.cache | count 4
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
diff --git a/llvm/include/llvm/Support/CachePruning.h b/llvm/include/llvm/Support/CachePruning.h
index 46bab38..e826938 100644
--- a/llvm/include/llvm/Support/CachePruning.h
+++ b/llvm/include/llvm/Support/CachePruning.h
@@ -52,6 +52,10 @@
/// Peform pruning using the supplied policy, returns true if pruning
/// occured, i.e. if Policy.Interval was expired.
+///
+/// As a safeguard against data loss if the user specifies the wrong directory
+/// as their cache directory, this function will ignore files not matching the
+/// pattern "llvmcache-*".
bool pruneCache(StringRef Path, CachePruningPolicy Policy);
} // namespace llvm
diff --git a/llvm/lib/LTO/Caching.cpp b/llvm/lib/LTO/Caching.cpp
index 16edbec..00373dd 100644
--- a/llvm/lib/LTO/Caching.cpp
+++ b/llvm/lib/LTO/Caching.cpp
@@ -27,9 +27,11 @@
return errorCodeToError(EC);
return [=](unsigned Task, StringRef Key) -> AddStreamFn {
- // First, see if we have a cache hit.
+ // This choice of file name allows the cache to be pruned (see pruneCache()
+ // in include/llvm/Support/CachePruning.h).
SmallString<64> EntryPath;
- sys::path::append(EntryPath, CacheDirectoryPath, Key);
+ sys::path::append(EntryPath, CacheDirectoryPath, "llvmcache-" + Key);
+ // First, see if we have a cache hit.
ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
MemoryBuffer::getFile(EntryPath);
if (MBOrErr) {
diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index b793d0c..aa4d32a 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -348,7 +348,10 @@
ArrayRef<uint8_t>((const uint8_t *)&Entry, sizeof(GlobalValue::GUID)));
}
- sys::path::append(EntryPath, CachePath, toHex(Hasher.result()));
+ // This choice of file name allows the cache to be pruned (see pruneCache()
+ // in include/llvm/Support/CachePruning.h).
+ sys::path::append(EntryPath, CachePath,
+ "llvmcache-" + toHex(Hasher.result()));
}
// Access the path to this entry in the cache.
diff --git a/llvm/lib/Support/CachePruning.cpp b/llvm/lib/Support/CachePruning.cpp
index 5d81e10..aca1236 100644
--- a/llvm/lib/Support/CachePruning.cpp
+++ b/llvm/lib/Support/CachePruning.cpp
@@ -180,8 +180,11 @@
// Walk all of the files within this directory.
for (sys::fs::directory_iterator File(CachePathNative, EC), FileEnd;
File != FileEnd && !EC; File.increment(EC)) {
- // Do not touch the timestamp.
- if (File->path() == TimestampFile)
+ // Ignore any files not beginning with the string "llvmcache-". This
+ // includes the timestamp file as well as any files created by the user.
+ // This acts as a safeguard against data loss if the user specifies the
+ // wrong directory as their cache directory.
+ if (!sys::path::filename(File->path()).startswith("llvmcache-"))
continue;
// Look at this file. If we can't stat it, there's nothing interesting
diff --git a/llvm/test/ThinLTO/X86/cache.ll b/llvm/test/ThinLTO/X86/cache.ll
index d654d34..426654f 100644
--- a/llvm/test/ThinLTO/X86/cache.ll
+++ b/llvm/test/ThinLTO/X86/cache.ll
@@ -23,11 +23,16 @@
; RUN: opt -module-hash -module-summary %s -o %t.bc
; RUN: opt -module-hash -module-summary %p/Inputs/cache.ll -o %t2.bc
-; Verify that enabling caching is working
+; Verify that enabling caching is working, and that the pruner only removes
+; files matching the pattern "llvmcache-*".
; RUN: rm -Rf %t.cache && mkdir %t.cache
+; RUN: touch -t 197001011200 %t.cache/llvmcache-foo %t.cache/foo
; RUN: llvm-lto -thinlto-action=run -exported-symbol=globalfunc %t2.bc %t.bc -thinlto-cache-dir %t.cache
+; RUN: ls %t.cache | count 4
; RUN: ls %t.cache/llvmcache.timestamp
-; RUN: ls %t.cache | count 3
+; RUN: ls %t.cache/foo
+; RUN: not ls %t.cache/llvmcache-foo
+; RUN: ls %t.cache/llvmcache-* | count 2
; Verify that enabling caching is working with llvm-lto2
; RUN: rm -Rf %t.cache
@@ -36,6 +41,7 @@
; RUN: -r=%t2.bc,_globalfunc,lx \
; RUN: -r=%t.bc,_globalfunc,plx
; RUN: ls %t.cache | count 2
+; RUN: ls %t.cache/llvmcache-* | count 2
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"