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[Autolink] Autolinking on COFF for Cygwin/MinGW #3887

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Merged
merged 1 commit into from
Aug 7, 2016
Merged

[Autolink] Autolinking on COFF for Cygwin/MinGW #3887

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2 changes: 1 addition & 1 deletion docs/Testing.rst
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Expand Up @@ -273,7 +273,7 @@ code for the target that is not the build machine:
``armv7``, ``armv7k``, ``arm64``).

* ``%target-os``: the target operating system (``macosx``, ``darwin``,
``linux``, ``freebsd``).
``linux``, ``freebsd``, ``windows-cygnus``, ``windows-gnu``).

* ``%target-object-format``: the platform's object format (``elf``, ``macho``,
``coff``).
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3 changes: 2 additions & 1 deletion lib/Driver/Driver.cpp
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Expand Up @@ -1316,7 +1316,8 @@ void Driver::buildActions(const ToolChain &TC,
if (OI.shouldLink() && !AllLinkerInputs.empty()) {
auto *LinkAction = new LinkJobAction(AllLinkerInputs, OI.LinkAction);

if (TC.getTriple().getObjectFormat() == llvm::Triple::ELF) {
if (TC.getTriple().getObjectFormat() == llvm::Triple::ELF ||
TC.getTriple().isOSCygMing()) {
// On ELF platforms there's no built in autolinking mechanism, so we
// pull the info we need from the .o files directly and pass them as an
// argument input file to the linker.
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1 change: 1 addition & 0 deletions test/AutolinkExtract/empty.swift
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Expand Up @@ -4,3 +4,4 @@
// REQUIRES: autolink-extract

// CHECK-elf: -lswiftCore
// CHECK-coff: -lswiftCore
1 change: 1 addition & 0 deletions test/AutolinkExtract/empty_archive.swift
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Expand Up @@ -6,3 +6,4 @@
// REQUIRES: autolink-extract

// CHECK-elf: -lswiftCore
// CHECK-coff: -lswiftCore
3 changes: 3 additions & 0 deletions test/AutolinkExtract/import.swift
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Expand Up @@ -9,4 +9,7 @@
// CHECK-elf-DAG: -lswiftCore
// CHECK-elf-DAG: -lempty

// CHECK-coff-DAG: -lswiftCore
// CHECK-coff-DAG: -lempty

import empty
3 changes: 3 additions & 0 deletions test/AutolinkExtract/import_archive.swift
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Expand Up @@ -10,4 +10,7 @@
// CHECK-elf-DAG: -lswiftCore
// CHECK-elf-DAG: -lempty

// CHECK-coff-DAG: -lswiftCore
// CHECK-coff-DAG: -lempty

import empty
2 changes: 2 additions & 0 deletions test/AutolinkExtract/linker-order.ll
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@@ -1,4 +1,6 @@
; RUN: llc -mtriple armv7--linux-gnueabihf -filetype obj -o - %s | %target-swift-autolink-extract -o - - | FileCheck %s
; RUN: llc -mtriple x86_64--windows-gnu -filetype obj -o - %s | %target-swift-autolink-extract -o - - | FileCheck %s
; RUN: llc -mtriple x86_64--windows-cygnus -filetype obj -o - %s | %target-swift-autolink-extract -o - - | FileCheck %s
; REQUIRES: autolink-extract

; Ensure that the options in the object file preserve ordering. The linker
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25 changes: 19 additions & 6 deletions test/lit.cfg
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Expand Up @@ -691,17 +691,30 @@ if run_vendor == 'apple':
"%s clang++ %s" %
(xcrun_prefix, config.target_cc_options))

elif run_os == 'linux-gnu' or run_os == 'linux-gnueabihf' or run_os == 'freebsd':
# Linux/FreeBSD
if run_os == 'freebsd':
elif run_os in ['linux-gnu', 'linux-gnueabihf', 'freebsd', 'windows-cygnus', 'windows-gnu']:
# Linux/FreeBSD/Cygwin
if run_os == 'windows-cygnus':
lit_config.note("Testing Cygwin " + config.variant_triple)
config.target_object_format = "coff"
config.target_dylib_extension = "dll"
config.target_sdk_name = "cygwin"
elif run_os == 'windows-gnu':
lit_config.note("Testing MinGW " + config.variant_triple)
config.target_object_format = "coff"
config.target_dylib_extension = "dll"
config.target_sdk_name = "mingw"
elif run_os == 'freebsd':
lit_config.note("Testing FreeBSD " + config.variant_triple)
config.target_object_format = "elf"
config.target_dylib_extension = "so"
config.target_sdk_name = "freebsd"
else:
lit_config.note("Testing Linux " + config.variant_triple)
config.target_object_format = "elf"
config.target_dylib_extension = "so"
config.target_object_format = "elf"
config.target_dylib_extension = "so"
config.target_sdk_name = "linux"
config.target_runtime = "native"
config.target_swift_autolink_extract = inferSwiftBinary("swift-autolink-extract")
config.target_sdk_name = "freebsd" if run_os == "freebsd" else "linux"
config.target_build_swift = (
'%s -target %s %s %s %s %s'
% (config.swiftc, config.variant_triple, resource_dir_opt, mcp_opt,
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55 changes: 34 additions & 21 deletions tools/driver/autolink_extract_main.cpp
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Expand Up @@ -31,6 +31,7 @@
#include "llvm/Option/Option.h"
#include "llvm/Object/Archive.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Object/COFF.h"
#include "llvm/Object/ELFObjectFile.h"

using namespace swift;
Expand Down Expand Up @@ -106,32 +107,44 @@ class AutolinkExtractInvocation {
}
};

// Look inside the binary 'Bin' and append any linker flags found in its
// ".swift1_autolink_entries" section to 'LinkerFlags'. If 'Bin' is an archive,
// recursively look inside all children within the archive. Return 'true' if
// there was an error, and 'false' otherwise.
/// Look inside the object file 'ObjectFile' and append any linker flags found in
/// its ".swift1_autolink_entries" section to 'LinkerFlags'.
static void
extractLinkerFlagsFromObjectFile(const llvm::object::ObjectFile *ObjectFile,
std::vector<std::string> &LinkerFlags) {
// Search for the section we hold autolink entries in
for (auto &Section : ObjectFile->sections()) {
llvm::StringRef SectionName;
Section.getName(SectionName);
if (SectionName == ".swift1_autolink_entries") {
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This isn't valid for COFF. COFF has a 8-character limit on section names.

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I quoted the description of the name field in 3. Section Table (Section Headers) from MS PECOFF.

... For longer names, this field contains a slash (/) that is followed by an ASCII 
representation of a decimal number that is an offset into the string table.
Executable images do not use a string table and do not support section names longer
than 8 characters. Long names in object files are truncated if they are emitted to 
an executable file.

Because the section '.swift1_autolink_entries' will not be emitted to an executable file, we can use the long name for autolink feature. But we can not use the long names '.swift2_protocol_conformances' and '.swift2_type_metadata' instead of '.sw2prtc' or '.sw2tymd', because they are emitted to an executable and loaded into the system memory.

llvm::StringRef SectionData;
Section.getContents(SectionData);

// entries are null-terminated, so extract them and push them into
// the set.
llvm::SmallVector<llvm::StringRef, 4> SplitFlags;
SectionData.split(SplitFlags, llvm::StringRef("\0", 1), -1,
/*KeepEmpty=*/false);
for (const auto &Flag : SplitFlags)
LinkerFlags.push_back(Flag);
}
}
}

/// Look inside the binary 'Bin' and append any linker flags found in its
/// ".swift1_autolink_entries" section to 'LinkerFlags'. If 'Bin' is an archive,
/// recursively look inside all children within the archive. Return 'true' if
/// there was an error, and 'false' otherwise.
static bool extractLinkerFlags(const llvm::object::Binary *Bin,
CompilerInstance &Instance,
StringRef BinaryFileName,
std::vector<std::string> &LinkerFlags) {
if (auto *ObjectFile = llvm::dyn_cast<llvm::object::ELFObjectFileBase>(Bin)) {
// Search for the section we hold autolink entries in
for (auto &Section : ObjectFile->sections()) {
llvm::StringRef SectionName;
Section.getName(SectionName);
if (SectionName == ".swift1_autolink_entries") {
llvm::StringRef SectionData;
Section.getContents(SectionData);

// entries are null-terminated, so extract them and push them into
// the set.
llvm::SmallVector<llvm::StringRef, 4> SplitFlags;
SectionData.split(SplitFlags, llvm::StringRef("\0", 1), -1,
/*KeepEmpty=*/false);
for (const auto &Flag : SplitFlags)
LinkerFlags.push_back(Flag);
}
}
extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags);
return false;
} else if (auto *ObjectFile =
llvm::dyn_cast<llvm::object::COFFObjectFile>(Bin)) {
extractLinkerFlagsFromObjectFile(ObjectFile, LinkerFlags);
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Why duplicate the same logic? It seems that you should do:

if (auto *OF = llvm::dyn_cast<llvm::object::ObjectFile>(Bin))
  extractLinkerFlagsFromObjectFile(ObjectFile, OF, LinkerFlags);

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@tinysun212 tinysun212 Aug 7, 2016 •
edited
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That's a good point.

I considered the side effect that the MachO object files would not generate the error (of message "Don't know how to extract from object file").

If we don't care for the handling of MachO object files, the patch can be more simpler.
@gribozavr, How do you think about this ?

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I think we don't care about MachO files being passed to this utility. This utility is not user-facing, it is only invoked by the driver.

return false;
} else if (auto *Archive = llvm::dyn_cast<llvm::object::Archive>(Bin)) {
for (const auto &Child : Archive->children()) {
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