[llvm][TargetParser] Return StringMap from getHostCPUFeatures

clang/lib/Driver/ToolChains/Arch/ARM.cpp

@@ -591,9 +591,9 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
 
   // Add CPU features for generic CPUs
   if (CPUName == "native") {
-    llvm::StringMap<bool> HostFeatures;
-    if (llvm::sys::getHostCPUFeatures(HostFeatures))
-      for (auto &F : HostFeatures)
+    if (std::optional<llvm::StringMap<bool>> HostFeatures =
+            llvm::sys::getHostCPUFeatures())
+      for (auto &F : *HostFeatures)
         Features.push_back(
             Args.MakeArgString((F.second ? "+" : "-") + F.first()));
   } else if (!CPUName.empty()) {

clang/lib/Driver/ToolChains/Arch/X86.cpp

@@ -131,9 +131,9 @@ void x86::getX86TargetFeatures(const Driver &D, const llvm::Triple &Triple,
   // If -march=native, autodetect the feature list.
   if (const Arg *A = Args.getLastArg(clang::driver::options::OPT_march_EQ)) {
     if (StringRef(A->getValue()) == "native") {
-      llvm::StringMap<bool> HostFeatures;
-      if (llvm::sys::getHostCPUFeatures(HostFeatures))
-        for (auto &F : HostFeatures)
+      if (std::optional<llvm::StringMap<bool>> HostFeatures =
+              llvm::sys::getHostCPUFeatures())
+        for (auto &F : *HostFeatures)
           Features.push_back(
               Args.MakeArgString((F.second ? "+" : "-") + F.first()));
     }

lldb/utils/lit-cpuid/lit-cpuid.cpp

@@ -15,22 +15,23 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/TargetParser/Host.h"
 
+#include <optional>
+
 using namespace llvm;
 
 int main(int argc, char **argv) {
 #if defined(__i386__) || defined(_M_IX86) || \
     defined(__x86_64__) || defined(_M_X64)
-  StringMap<bool> features;
-
-  if (!sys::getHostCPUFeatures(features))
+  if (const std::optional<StringMap<bool>> features =
+          sys::getHostCPUFeatures(features)) {
+    if (features->lookup("sse"))
+      outs() << "sse\n";
+    if (features->lookup("avx"))
+      outs() << "avx\n";
+    if (features->lookup("avx512f"))
+      outs() << "avx512f\n";
+  } else
     return 1;
-
-  if (features["sse"])
-    outs() << "sse\n";
-  if (features["avx"])
-    outs() << "avx\n";
-  if (features["avx512f"])
-    outs() << "avx512f\n";
 #endif
 
   return 0;

llvm/include/llvm/TargetParser/Host.h

@@ -13,6 +13,7 @@
 #ifndef LLVM_TARGETPARSER_HOST_H
 #define LLVM_TARGETPARSER_HOST_H
 
+#include <optional>
 #include <string>
 
 namespace llvm {
@@ -47,13 +48,12 @@ namespace sys {
   /// The particular format of the names are target dependent, and suitable for
   /// passing as -mattr to the target which matches the host.
   ///
-  /// \param Features - A string mapping feature names to either
-  /// true (if enabled) or false (if disabled). This routine makes no guarantees
-  /// about exactly which features may appear in this map, except that they are
-  /// all valid LLVM feature names.
-  ///
-  /// \return - True on success.
-  bool getHostCPUFeatures(StringMap<bool, MallocAllocator> &Features);
+  /// \return - If feature detection succeeds, a string map mapping feature
+  /// names to either true (if enabled) or false (if disabled). This routine
+  /// makes no guarantees about exactly which features may appear in this map,
+  /// except that they are all valid LLVM feature names. If feature detection
+  /// fails, an empty optional is returned.
+  std::optional<StringMap<bool, MallocAllocator>> getHostCPUFeatures();
 
   /// This is a function compatible with cl::AddExtraVersionPrinter, which adds
   /// info about the current target triple and detected CPU.

llvm/lib/CodeGen/CommandFlags.cpp

@@ -624,12 +624,10 @@ std::string codegen::getFeaturesStr() {
   // This is necessary for x86 where the CPU might not support all the
   // features the autodetected CPU name lists in the target. For example,
   // not all Sandybridge processors support AVX.
-  if (getMCPU() == "native") {
-    StringMap<bool> HostFeatures;
-    if (sys::getHostCPUFeatures(HostFeatures))
-      for (const auto &[Feature, IsEnabled] : HostFeatures)
+  if (getMCPU() == "native")
+    if (std::optional<StringMap<bool>> HostFeatures = sys::getHostCPUFeatures())
+      for (const auto &[Feature, IsEnabled] : *HostFeatures)
         Features.AddFeature(Feature, IsEnabled);
-  }
 
   for (auto const &MAttr : getMAttrs())
     Features.AddFeature(MAttr);
@@ -644,12 +642,10 @@ std::vector<std::string> codegen::getFeatureList() {
   // This is necessary for x86 where the CPU might not support all the
   // features the autodetected CPU name lists in the target. For example,
   // not all Sandybridge processors support AVX.
-  if (getMCPU() == "native") {
-    StringMap<bool> HostFeatures;
-    if (sys::getHostCPUFeatures(HostFeatures))
-      for (const auto &[Feature, IsEnabled] : HostFeatures)
+  if (getMCPU() == "native")
+    if (std::optional<StringMap<bool>> HostFeatures = sys::getHostCPUFeatures())
+      for (const auto &[Feature, IsEnabled] : *HostFeatures)
         Features.AddFeature(Feature, IsEnabled);
-  }
 
   for (auto const &MAttr : getMAttrs())
     Features.AddFeature(MAttr);

llvm/lib/ExecutionEngine/Orc/JITTargetMachineBuilder.cpp

@@ -28,10 +28,10 @@ Expected<JITTargetMachineBuilder> JITTargetMachineBuilder::detectHost() {
   // Retrieve host CPU name and sub-target features and add them to builder.
   // Relocation model, code model and codegen opt level are kept to default
   // values.
-  llvm::StringMap<bool> FeatureMap;
-  llvm::sys::getHostCPUFeatures(FeatureMap);
-  for (auto &Feature : FeatureMap)
-    TMBuilder.getFeatures().AddFeature(Feature.first(), Feature.second);
+  if (std::optional<StringMap<bool>> FeatureMap =
+          llvm::sys::getHostCPUFeatures())
+    for (auto &Feature : *FeatureMap)
+      TMBuilder.getFeatures().AddFeature(Feature.first(), Feature.second);
 
   TMBuilder.setCPU(std::string(llvm::sys::getHostCPUName()));
 

llvm/lib/Target/TargetMachineC.cpp

@@ -363,10 +363,9 @@ char *LLVMGetHostCPUName(void) {
 
 char *LLVMGetHostCPUFeatures(void) {
   SubtargetFeatures Features;
-  StringMap<bool> HostFeatures;
 
-  if (sys::getHostCPUFeatures(HostFeatures))
-    for (const auto &[Feature, IsEnabled] : HostFeatures)
+  if (std::optional<StringMap<bool>> HostFeatures = sys::getHostCPUFeatures())
+    for (const auto &[Feature, IsEnabled] : *HostFeatures)
       Features.AddFeature(Feature, IsEnabled);
 
   return strdup(Features.getString().c_str());

llvm/lib/TargetParser/Host.cpp

@@ -1710,15 +1710,17 @@ VendorSignatures getVendorSignature(unsigned *MaxLeaf) {
 
 #if defined(__i386__) || defined(_M_IX86) || \
     defined(__x86_64__) || defined(_M_X64)
-bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
+std::optional<StringMap<bool>> sys::getHostCPUFeatures() {
   unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
   unsigned MaxLevel;
 
   if (getX86CpuIDAndInfo(0, &MaxLevel, &EBX, &ECX, &EDX) || MaxLevel < 1)
-    return false;
+    return {};
 
   getX86CpuIDAndInfo(1, &EAX, &EBX, &ECX, &EDX);
 
+  StringMap<bool> Features;
+
   Features["cx8"]    = (EDX >>  8) & 1;
   Features["cmov"]   = (EDX >> 15) & 1;
   Features["mmx"]    = (EDX >> 23) & 1;
@@ -1903,13 +1905,13 @@ bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   Features["avx10.1-512"] =
       Features["avx10.1-256"] && HasLeaf24 && ((EBX >> 18) & 1);
 
-  return true;
+  return Features;
 }
 #elif defined(__linux__) && (defined(__arm__) || defined(__aarch64__))
-bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
+std::optional<StringMap<bool>> sys::getHostCPUFeatures() {
   std::unique_ptr<llvm::MemoryBuffer> P = getProcCpuinfoContent();
   if (!P)
-    return false;
+    return {};
 
   SmallVector<StringRef, 32> Lines;
   P->getBuffer().split(Lines, "\n");
@@ -1929,6 +1931,7 @@ bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   uint32_t crypto = 0;
 #endif
 
+  StringMap<bool> Features;
   for (unsigned I = 0, E = CPUFeatures.size(); I != E; ++I) {
     StringRef LLVMFeatureStr = StringSwitch<StringRef>(CPUFeatures[I])
 #if defined(__aarch64__)
@@ -1972,38 +1975,42 @@ bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
     Features["crypto"] = true;
 #endif
 
-  return true;
+  return Features;
 }
 #elif defined(_WIN32) && (defined(__aarch64__) || defined(_M_ARM64))
-bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
+std::optional<StringMap<bool>> sys::getHostCPUFeatures() {
+  std::optional<StringMap<bool>> Features;
+
   if (IsProcessorFeaturePresent(PF_ARM_NEON_INSTRUCTIONS_AVAILABLE))
     Features["neon"] = true;
   if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE))
     Features["crc"] = true;
   if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE))
     Features["crypto"] = true;
 
-  return true;
+  return Features;
 }
 #elif defined(__linux__) && defined(__loongarch__)
 #include <sys/auxv.h>
-bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
+std::optional<StringMap<bool>> sys::getHostCPUFeatures() {
   unsigned long hwcap = getauxval(AT_HWCAP);
   bool HasFPU = hwcap & (1UL << 3); // HWCAP_LOONGARCH_FPU
   uint32_t cpucfg2 = 0x2;
   __asm__("cpucfg %[cpucfg2], %[cpucfg2]\n\t" : [cpucfg2] "+r"(cpucfg2));
 
+  std::optional<StringMap<bool>> Features;
+
   Features["f"] = HasFPU && (cpucfg2 & (1U << 1)); // CPUCFG.2.FP_SP
   Features["d"] = HasFPU && (cpucfg2 & (1U << 2)); // CPUCFG.2.FP_DP
 
   Features["lsx"] = hwcap & (1UL << 4);  // HWCAP_LOONGARCH_LSX
   Features["lasx"] = hwcap & (1UL << 5); // HWCAP_LOONGARCH_LASX
   Features["lvz"] = hwcap & (1UL << 9);  // HWCAP_LOONGARCH_LVZ
 
-  return true;
+  return Features;
 }
 #else
-bool sys::getHostCPUFeatures(StringMap<bool> &Features) { return false; }
+std::optional<StringMap<bool>> sys::getHostCPUFeatures() { return {}; }
 #endif
 
 #if __APPLE__