[🍒 stable/20240723] [Coverage][WebAssembly] Add initial support for WebAssembly/WASI

clang/lib/Driver/ToolChains/WebAssembly.cpp

@@ -155,6 +155,8 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     AddRunTimeLibs(ToolChain, ToolChain.getDriver(), CmdArgs, Args);
   }
 
+  ToolChain.addProfileRTLibs(Args, CmdArgs);
+
   CmdArgs.push_back("-o");
   CmdArgs.push_back(Output.getFilename());
 

compiler-rt/cmake/Modules/AllSupportedArchDefs.cmake

@@ -71,7 +71,7 @@ set(ALL_HWASAN_SUPPORTED_ARCH ${X86_64} ${ARM64} ${RISCV64})
 set(ALL_MEMPROF_SUPPORTED_ARCH ${X86_64})
 set(ALL_PROFILE_SUPPORTED_ARCH ${X86} ${X86_64} ${ARM32} ${ARM64} ${PPC32} ${PPC64}
     ${MIPS32} ${MIPS64} ${S390X} ${SPARC} ${SPARCV9} ${HEXAGON}
-    ${RISCV32} ${RISCV64} ${LOONGARCH64})
+    ${RISCV32} ${RISCV64} ${LOONGARCH64} ${WASM32})
 set(ALL_CTX_PROFILE_SUPPORTED_ARCH ${X86_64})
 set(ALL_TSAN_SUPPORTED_ARCH ${X86_64} ${MIPS64} ${ARM64} ${PPC64} ${S390X}
     ${LOONGARCH64} ${RISCV64})

compiler-rt/cmake/config-ix.cmake

@@ -816,7 +816,7 @@ else()
 endif()
 
 if (PROFILE_SUPPORTED_ARCH AND NOT LLVM_USE_SANITIZER AND
-    OS_NAME MATCHES "Darwin|Linux|FreeBSD|Windows|Android|Fuchsia|SunOS|NetBSD|AIX")
+    OS_NAME MATCHES "Darwin|Linux|FreeBSD|Windows|Android|Fuchsia|SunOS|NetBSD|AIX|WASI")
   set(COMPILER_RT_HAS_PROFILE TRUE)
 else()
   set(COMPILER_RT_HAS_PROFILE FALSE)

compiler-rt/lib/profile/CMakeLists.txt

@@ -38,6 +38,17 @@ int main() {
 
 " COMPILER_RT_TARGET_HAS_FCNTL_LCK)
 
+CHECK_CXX_SOURCE_COMPILES("
+#include <sys/file.h>
+
+int fd;
+int main() {
+  flock(fd, LOCK_EX);
+  return 0;
+}
+
+" COMPILER_RT_TARGET_HAS_FLOCK)
+
 CHECK_CXX_SOURCE_COMPILES("
 #include <sys/utsname.h>
 int main() {
@@ -93,6 +104,13 @@ if(FUCHSIA OR UNIX)
      -Wno-pedantic)
 endif()
 
+if(CMAKE_SYSTEM_NAME STREQUAL "WASI")
+  set(EXTRA_FLAGS
+      ${EXTRA_FLAGS}
+      -D_WASI_EMULATED_MMAN
+      -D_WASI_EMULATED_GETPID)
+endif()
+
 if(COMPILER_RT_TARGET_HAS_ATOMICS)
  set(EXTRA_FLAGS
      ${EXTRA_FLAGS}
@@ -105,6 +123,12 @@ if(COMPILER_RT_TARGET_HAS_FCNTL_LCK)
      -DCOMPILER_RT_HAS_FCNTL_LCK=1)
 endif()
 
+if(COMPILER_RT_TARGET_HAS_FLOCK)
+  set(EXTRA_FLAGS
+      ${EXTRA_FLAGS}
+      -DCOMPILER_RT_HAS_FLOCK=1)
+endif()
+
 if(COMPILER_RT_TARGET_HAS_UNAME)
  set(EXTRA_FLAGS
      ${EXTRA_FLAGS}

compiler-rt/lib/profile/GCDAProfiling.c

@@ -584,7 +584,7 @@ void llvm_reset_counters(void) {
   }
 }
 
-#if !defined(_WIN32)
+#if !defined(_WIN32) && !defined(__wasm__)
 COMPILER_RT_VISIBILITY
 pid_t __gcov_fork() {
   pid_t parent_pid = getpid();

compiler-rt/lib/profile/InstrProfilingFile.c

@@ -13,7 +13,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#if !defined(__wasi__)
 #include <signal.h>
+#endif
 #ifdef _MSC_VER
 /* For _alloca. */
 #include <malloc.h>

compiler-rt/lib/profile/InstrProfilingPlatformLinux.c

@@ -6,11 +6,11 @@
 |*
 \*===----------------------------------------------------------------------===*/
 
-#if defined(__linux__) || defined(__FreeBSD__) || defined(__Fuchsia__) || \
-    (defined(__sun__) && defined(__svr4__)) || defined(__NetBSD__) || \
-    defined(_AIX)
+#if defined(__linux__) || defined(__FreeBSD__) || defined(__Fuchsia__) ||      \
+    (defined(__sun__) && defined(__svr4__)) || defined(__NetBSD__) ||          \
+    defined(_AIX) || defined(__wasm__)
 
-#if !defined(_AIX)
+#if !defined(_AIX) && !defined(__wasm__)
 #include <elf.h>
 #include <link.h>
 #endif

compiler-rt/lib/profile/InstrProfilingPlatformOther.c

@@ -8,7 +8,8 @@
 
 #if !defined(__APPLE__) && !defined(__linux__) && !defined(__FreeBSD__) &&     \
     !defined(__Fuchsia__) && !(defined(__sun__) && defined(__svr4__)) &&       \
-    !defined(__NetBSD__) && !defined(_WIN32) && !defined(_AIX)
+    !defined(__NetBSD__) && !defined(_WIN32) && !defined(_AIX) &&              \
+    !defined(__wasm__)
 
 #include <stdlib.h>
 #include <stdio.h>

compiler-rt/lib/profile/InstrProfilingPort.h

@@ -54,7 +54,7 @@
 #endif
 
 #define COMPILER_RT_MAX_HOSTLEN 128
-#ifdef __ORBIS__
+#if defined(__ORBIS__) || defined(__wasi__)
 #define COMPILER_RT_GETHOSTNAME(Name, Len) ((void)(Name), (void)(Len), (-1))
 #else
 #define COMPILER_RT_GETHOSTNAME(Name, Len) lprofGetHostName(Name, Len)

compiler-rt/lib/profile/InstrProfilingUtil.c

@@ -25,7 +25,9 @@
 #include <sys/utsname.h>
 #endif
 
+#if !defined(__wasi__)
 #include <signal.h>
+#endif
 #include <stdlib.h>
 #include <string.h>
 
@@ -153,9 +155,12 @@ COMPILER_RT_VISIBILITY int lprofLockFd(int fd) {
     }
   }
   return 0;
-#else
+#elif defined(COMPILER_RT_HAS_FLOCK) || defined(_WIN32)
+  // Windows doesn't have flock but WindowsMMap.h provides a shim
   flock(fd, LOCK_EX);
   return 0;
+#else
+  return 0;
 #endif
 }
 
@@ -178,9 +183,12 @@ COMPILER_RT_VISIBILITY int lprofUnlockFd(int fd) {
     }
   }
   return 0;
-#else
+#elif defined(COMPILER_RT_HAS_FLOCK) || defined(_WIN32)
+  // Windows doesn't have flock but WindowsMMap.h provides a shim
   flock(fd, LOCK_UN);
   return 0;
+#else
+  return 0;
 #endif
 }
 
@@ -332,6 +340,8 @@ COMPILER_RT_VISIBILITY void lprofInstallSignalHandler(int sig,
   if (err == SIG_ERR)
     PROF_WARN("Unable to install an exit signal handler for %d (errno = %d).\n",
               sig, errno);
+#elif defined(__wasi__)
+  // WASI doesn't support signal.
 #else
   struct sigaction sigact;
   memset(&sigact, 0, sizeof(sigact));
@@ -372,8 +382,8 @@ COMPILER_RT_VISIBILITY void lprofRestoreSigKill(void) {
 
 COMPILER_RT_VISIBILITY int lprofReleaseMemoryPagesToOS(uintptr_t Begin,
                                                        uintptr_t End) {
-#if defined(__ve__)
-  // VE doesn't support madvise.
+#if defined(__ve__) || defined(__wasi__)
+  // VE and WASI doesn't support madvise.
   return 0;
 #else
   size_t PageSize = getpagesize();

lld/test/wasm/custom-section-align.s

@@ -0,0 +1,31 @@
+# RUN: llvm-mc -filetype=obj -triple=wasm32-unknown-unknown -o %t.o %s
+# RUN: wasm-ld --no-entry %t.o -o %t.wasm
+# RUN: obj2yaml %t.wasm | FileCheck %s
+
+# Check that "__llvm_covfun" custom section is aligned to 8 bytes.
+
+        .section        .custom_section.__llvm_covfun,"GR",@,__covrec_A
+        .int32  1
+        .int8   2
+# pad   .int8   0
+#       .int8   0
+#       .int8   0
+
+        .section        .custom_section.__llvm_covfun,"GR",@,__covrec_B
+        .int32  3
+
+# CHECK:      - Type:            CUSTOM
+# CHECK-NEXT:   Name:            __llvm_covfun
+# CHECK-NEXT:   Payload:         '010000000200000003000000'
+
+# Check that regular custom sections are not aligned.
+        .section        .custom_section.foo,"GR",@,foo_A
+        .int32  1
+        .int8   2
+
+        .section        .custom_section.foo,"GR",@,foo_B
+        .int32  3
+
+# CHECK:      - Type:            CUSTOM
+# CHECK-NEXT:   Name:            foo
+# CHECK-NEXT:   Payload:         '010000000203000000'

lld/wasm/CMakeLists.txt

@@ -28,6 +28,7 @@ add_lld_library(lldWasm
   Object
   Option
   Passes
+  ProfileData
   Support
   TargetParser
 

lld/wasm/InputChunks.h

@@ -177,8 +177,9 @@ class MergeInputChunk : public InputChunk {
     inputSectionOffset = seg.SectionOffset;
   }
 
-  MergeInputChunk(const WasmSection &s, ObjFile *f)
-      : InputChunk(f, Merge, s.Name, 0, llvm::wasm::WASM_SEG_FLAG_STRINGS) {
+  MergeInputChunk(const WasmSection &s, ObjFile *f, uint32_t alignment)
+      : InputChunk(f, Merge, s.Name, alignment,
+                   llvm::wasm::WASM_SEG_FLAG_STRINGS) {
     assert(s.Type == llvm::wasm::WASM_SEC_CUSTOM);
     comdat = s.Comdat;
     rawData = s.Content;
@@ -234,6 +235,7 @@ class SyntheticMergedChunk : public InputChunk {
 
   void addMergeChunk(MergeInputChunk *ms) {
     comdat = ms->getComdat();
+    alignment = std::max(alignment, ms->alignment);
     ms->parent = this;
     chunks.push_back(ms);
   }
@@ -337,8 +339,8 @@ class SyntheticFunction : public InputFunction {
 // Represents a single Wasm Section within an input file.
 class InputSection : public InputChunk {
 public:
-  InputSection(const WasmSection &s, ObjFile *f)
-      : InputChunk(f, InputChunk::Section, s.Name),
+  InputSection(const WasmSection &s, ObjFile *f, uint32_t alignment)
+      : InputChunk(f, InputChunk::Section, s.Name, alignment),
         tombstoneValue(getTombstoneForSection(s.Name)), section(s) {
     assert(section.Type == llvm::wasm::WASM_SEC_CUSTOM);
     comdat = section.Comdat;

lld/wasm/InputFiles.cpp

@@ -18,6 +18,7 @@
 #include "llvm/BinaryFormat/Wasm.h"
 #include "llvm/Object/Binary.h"
 #include "llvm/Object/Wasm.h"
+#include "llvm/ProfileData/InstrProf.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/TarWriter.h"
 #include "llvm/Support/raw_ostream.h"
@@ -451,6 +452,18 @@ void SharedFile::parse() {
   }
 }
 
+// Returns the alignment for a custom section. This is used to concatenate
+// custom sections with the same name into a single custom section.
+static uint32_t getCustomSectionAlignment(const WasmSection &sec) {
+  // TODO: Add a section attribute for alignment in the linking spec.
+  if (sec.Name == getInstrProfSectionName(IPSK_covfun, Triple::Wasm) ||
+      sec.Name == getInstrProfSectionName(IPSK_covmap, Triple::Wasm)) {
+    // llvm-cov assumes that coverage metadata sections are 8-byte aligned.
+    return 8;
+  }
+  return 1;
+}
+
 WasmFileBase::WasmFileBase(Kind k, MemoryBufferRef m) : InputFile(k, m) {
   // Parse a memory buffer as a wasm file.
   LLVM_DEBUG(dbgs() << "Reading object: " << toString(this) << "\n");
@@ -520,10 +533,11 @@ void ObjFile::parse(bool ignoreComdats) {
       dataSection = &section;
     } else if (section.Type == WASM_SEC_CUSTOM) {
       InputChunk *customSec;
+      uint32_t alignment = getCustomSectionAlignment(section);
       if (shouldMerge(section))
-        customSec = make<MergeInputChunk>(section, this);
+        customSec = make<MergeInputChunk>(section, this, alignment);
       else
-        customSec = make<InputSection>(section, this);
+        customSec = make<InputSection>(section, this, alignment);
       customSec->discarded = isExcludedByComdat(customSec);
       customSections.emplace_back(customSec);
       customSections.back()->setRelocations(section.Relocations);

lld/wasm/OutputSections.cpp

@@ -249,6 +249,7 @@ void CustomSection::finalizeContents() {
 
   for (InputChunk *section : inputSections) {
     assert(!section->discarded);
+    payloadSize = alignTo(payloadSize, section->alignment);
     section->outSecOff = payloadSize;
     payloadSize += section->getSize();
   }

llvm/include/llvm/ProfileData/Coverage/CoverageMappingReader.h

@@ -180,6 +180,7 @@ class BinaryCoverageReader : public CoverageMappingReader {
   };
 
   using FuncRecordsStorage = std::unique_ptr<MemoryBuffer>;
+  using CoverageMapCopyStorage = std::unique_ptr<MemoryBuffer>;
 
 private:
   std::vector<std::string> Filenames;
@@ -195,9 +196,16 @@ class BinaryCoverageReader : public CoverageMappingReader {
   // D69471, which can split up function records into multiple sections on ELF.
   FuncRecordsStorage FuncRecords;
 
+  // Used to tie the lifetimes of an optional copy of the coverage mapping data
+  // to the lifetime of this BinaryCoverageReader instance. Needed to support
+  // Wasm object format, which might require realignment of section contents.
+  CoverageMapCopyStorage CoverageMapCopy;
+
   BinaryCoverageReader(std::unique_ptr<InstrProfSymtab> Symtab,
-                       FuncRecordsStorage &&FuncRecords)
-      : ProfileNames(std::move(Symtab)), FuncRecords(std::move(FuncRecords)) {}
+                       FuncRecordsStorage &&FuncRecords,
+                       CoverageMapCopyStorage &&CoverageMapCopy)
+      : ProfileNames(std::move(Symtab)), FuncRecords(std::move(FuncRecords)),
+        CoverageMapCopy(std::move(CoverageMapCopy)) {}
 
 public:
   BinaryCoverageReader(const BinaryCoverageReader &) = delete;
@@ -212,6 +220,7 @@ class BinaryCoverageReader : public CoverageMappingReader {
   static Expected<std::unique_ptr<BinaryCoverageReader>>
   createCoverageReaderFromBuffer(
       StringRef Coverage, FuncRecordsStorage &&FuncRecords,
+      CoverageMapCopyStorage &&CoverageMap,
       std::unique_ptr<InstrProfSymtab> ProfileNamesPtr, uint8_t BytesInAddress,
       llvm::endianness Endian, StringRef CompilationDir = "");
 

llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp

@@ -2173,7 +2173,11 @@ MCSection *TargetLoweringObjectFileWasm::getExplicitSectionGlobal(
   // This could be avoided if all data segements (the wasm sense) were
   // represented as their own sections (in the llvm sense).
   // TODO(sbc): https://github.com/WebAssembly/tool-conventions/issues/138
-  if (Name == ".llvmcmd" || Name == ".llvmbc")
+  if (Name == getInstrProfSectionName(IPSK_covmap, Triple::Wasm,
+                                      /*AddSegmentInfo=*/false) ||
+      Name == getInstrProfSectionName(IPSK_covfun, Triple::Wasm,
+                                      /*AddSegmentInfo=*/false) ||
+      Name == ".llvmbc" || Name == ".llvmcmd")
     Kind = SectionKind::getMetadata();
 
   StringRef Group = "";

llvm/lib/MC/MCContext.cpp

@@ -756,6 +756,11 @@ MCSectionWasm *MCContext::getWasmSection(const Twine &Section, SectionKind K,
   if (!Group.isTriviallyEmpty() && !Group.str().empty()) {
     GroupSym = cast<MCSymbolWasm>(getOrCreateSymbol(Group));
     GroupSym->setComdat(true);
+    if (K.isMetadata() && !GroupSym->getType().has_value()) {
+      // Comdat group symbol associated with a custom section is a section
+      // symbol (not a data symbol).
+      GroupSym->setType(wasm::WASM_SYMBOL_TYPE_SECTION);
+    }
   }
 
   return getWasmSection(Section, K, Flags, GroupSym, UniqueID);