Page align buffer pointer and revert performance regression.

Author: johnno1962

lld/MachO/Driver.cpp

@@ -350,8 +350,6 @@ void multiThreadedPageInBackground(DeferredFiles &deferred) {
     const StringRef &buff = deferredFile.buffer.getBuffer();
     if (buff.size() > largeArchive)
       return;
-    if (((uintptr_t)buff.data() & (pageSize - 1)))
-      return; // Not mmap()'d (not page aligned).
 
     totalBytes += buff.size();
     numDeferedFilesAdvised += 1;
@@ -363,8 +361,10 @@ void multiThreadedPageInBackground(DeferredFiles &deferred) {
       LLVM_ATTRIBUTE_UNUSED volatile char t = *page;
 #else
 #define DEBUG_TYPE "lld-madvise"
-    if (madvise((void *)buff.data(), buff.size(), MADV_WILLNEED) < 0)
-      LLVM_DEBUG(llvm::dbgs() << "madvise() error: " << strerror(errno));
+    auto aligned = llvm::alignAddr(buff.data(), Align(pageSize));
+    auto rounded = llvm::alignTo(buff.size(), Align(pageSize));
+    if (madvise((void *)aligned, rounded, MADV_WILLNEED) < 0)
+      LLVM_DEBUG(llvm::dbgs() << "madvise error: " << strerror(errno) << "\n");
 #undef DEBUG_TYPE
 #endif
   };

lld/MachO/InputFiles.cpp

@@ -217,7 +217,8 @@ std::optional<MemoryBufferRef> macho::readFile(StringRef path) {
   if (entry != cachedReads.end())
     return entry->second;
 
-  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr = MemoryBuffer::getFile(path);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr =
+      MemoryBuffer::getFile(path, false, /*RequiresNullTerminator*/ false);
   if (std::error_code ec = mbOrErr.getError()) {
     error("cannot open " + path + ": " + ec.message());
     return std::nullopt;

llvm/lib/Object/Archive.cpp

@@ -584,7 +584,8 @@ Expected<StringRef> Archive::Child::getBuffer() const {
   if (!FullNameOrErr)
     return FullNameOrErr.takeError();
   const std::string &FullName = *FullNameOrErr;
-  ErrorOr<std::unique_ptr<MemoryBuffer>> Buf = MemoryBuffer::getFile(FullName);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
+      MemoryBuffer::getFile(FullName, false, /*RequiresNullTerminator*/ false);
   if (std::error_code EC = Buf.getError())
     return errorCodeToError(EC);
   Parent->ThinBuffers.push_back(std::move(*Buf));