[WebAssembly] Add Emscripten OS definition + small_printf

The Emscripten OS provides a definition of __EMSCRIPTEN__, and also that it
supports iprintf optimizations.

Also define small_printf optimizations, which is a printf with float support
but not long double (which in wasm can be useful since long doubles are 128
bit and force linking of float128 emulation code). This part is based on
sunfish's https://reviews.llvm.org/D57620 (which can't land yet since
the WASI integration isn't ready yet).

Differential Revision: https://reviews.llvm.org/D60167

llvm-svn: 357552

include/llvm/ADT/Triple.h

@@ -186,7 +186,8 @@ public:
     HermitCore, // HermitCore Unikernel/Multikernel
     Hurd,       // GNU/Hurd
     WASI,       // Experimental WebAssembly OS
-    LastOSType = WASI
+    Emscripten,
+    LastOSType = Emscripten
   };
   enum EnvironmentType {
     UnknownEnvironment,
@@ -592,6 +593,11 @@ public:
     return getOS() == Triple::WASI;
   }
 
+  /// Tests whether the OS is Emscripten.
+  bool isOSEmscripten() const {
+    return getOS() == Triple::Emscripten;
+  }
+
   /// Tests whether the OS uses glibc.
   bool isOSGlibc() const {
     return (getOS() == Triple::Linux || getOS() == Triple::KFreeBSD ||

include/llvm/Analysis/TargetLibraryInfo.def

@@ -372,6 +372,15 @@ TLI_DEFINE_STRING_INTERNAL("__sinpi")
 /// float __sinpif(float x);
 TLI_DEFINE_ENUM_INTERNAL(sinpif)
 TLI_DEFINE_STRING_INTERNAL("__sinpif")
+/// int __small_fprintf(FILE *stream, const char *format, ...);
+TLI_DEFINE_ENUM_INTERNAL(small_fprintf)
+TLI_DEFINE_STRING_INTERNAL("__small_fprintf")
+/// int __small_printf(const char *format, ...);
+TLI_DEFINE_ENUM_INTERNAL(small_printf)
+TLI_DEFINE_STRING_INTERNAL("__small_printf")
+/// int __small_sprintf(char *str, const char *format, ...);
+TLI_DEFINE_ENUM_INTERNAL(small_sprintf)
+TLI_DEFINE_STRING_INTERNAL("__small_sprintf")
 /// double __sqrt_finite(double x);
 TLI_DEFINE_ENUM_INTERNAL(sqrt_finite)
 TLI_DEFINE_STRING_INTERNAL("__sqrt_finite")

lib/Analysis/TargetLibraryInfo.cpp

@@ -165,13 +165,21 @@ static void initialize(TargetLibraryInfoImpl &TLI, const Triple &T,
     TLI.setAvailableWithName(LibFunc_fputs, "fputs$UNIX2003");
   }
 
-  // iprintf and friends are only available on XCore and TCE.
-  if (T.getArch() != Triple::xcore && T.getArch() != Triple::tce) {
+  // iprintf and friends are only available on XCore, TCE, and Emscripten.
+  if (T.getArch() != Triple::xcore && T.getArch() != Triple::tce &&
+      T.getOS() != Triple::Emscripten) {
     TLI.setUnavailable(LibFunc_iprintf);
     TLI.setUnavailable(LibFunc_siprintf);
     TLI.setUnavailable(LibFunc_fiprintf);
   }
 
+  // __small_printf and friends are only available on Emscripten.
+  if (T.getOS() != Triple::Emscripten) {
+    TLI.setUnavailable(LibFunc_small_printf);
+    TLI.setUnavailable(LibFunc_small_sprintf);
+    TLI.setUnavailable(LibFunc_small_fprintf);
+  }
+
   if (T.isOSWindows() && !T.isOSCygMing()) {
     // XXX: The earliest documentation available at the moment is for VS2015/VC19:
     // https://docs.microsoft.com/en-us/cpp/c-runtime-library/floating-point-support?view=vs-2015
@@ -771,6 +779,7 @@ bool TargetLibraryInfoImpl::isValidProtoForLibFunc(const FunctionType &FTy,
   case LibFunc_stat:
   case LibFunc_statvfs:
   case LibFunc_siprintf:
+  case LibFunc_small_sprintf:
   case LibFunc_sprintf:
     return (NumParams >= 2 && FTy.getParamType(0)->isPointerTy() &&
             FTy.getParamType(1)->isPointerTy() &&
@@ -868,6 +877,7 @@ bool TargetLibraryInfoImpl::isValidProtoForLibFunc(const FunctionType &FTy,
   case LibFunc_getenv:
   case LibFunc_getpwnam:
   case LibFunc_iprintf:
+  case LibFunc_small_printf:
   case LibFunc_pclose:
   case LibFunc_perror:
   case LibFunc_printf:
@@ -947,6 +957,7 @@ bool TargetLibraryInfoImpl::isValidProtoForLibFunc(const FunctionType &FTy,
             FTy.getParamType(1)->isPointerTy());
   case LibFunc_fscanf:
   case LibFunc_fiprintf:
+  case LibFunc_small_fprintf:
   case LibFunc_fprintf:
     return (NumParams >= 2 && FTy.getReturnType()->isIntegerTy() &&
             FTy.getParamType(0)->isPointerTy() &&

lib/Support/Triple.cpp

@@ -208,6 +208,7 @@ StringRef Triple::getOSTypeName(OSType Kind) {
   case HermitCore: return "hermit";
   case Hurd: return "hurd";
   case WASI: return "wasi";
+  case Emscripten: return "emscripten";
   }
 
   llvm_unreachable("Invalid OSType");
@@ -506,6 +507,7 @@ static Triple::OSType parseOS(StringRef OSName) {
     .StartsWith("hermit", Triple::HermitCore)
     .StartsWith("hurd", Triple::Hurd)
     .StartsWith("wasi", Triple::WASI)
+    .StartsWith("emscripten", Triple::Emscripten)
     .Default(Triple::UnknownOS);
 }
 

lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -104,6 +104,12 @@ static bool callHasFloatingPointArgument(const CallInst *CI) {
   });
 }
 
+static bool callHasFP128Argument(const CallInst *CI) {
+  return any_of(CI->operands(), [](const Use &OI) {
+    return OI->getType()->isFP128Ty();
+  });
+}
+
 static Value *convertStrToNumber(CallInst *CI, StringRef &Str, int64_t Base) {
   if (Base < 2 || Base > 36)
     // handle special zero base
@@ -2051,6 +2057,20 @@ Value *LibCallSimplifier::optimizePrintF(CallInst *CI, IRBuilder<> &B) {
     B.Insert(New);
     return New;
   }
+
+  // printf(format, ...) -> __small_printf(format, ...) if no 128-bit floating point
+  // arguments.
+  if (TLI->has(LibFunc_small_printf) && !callHasFP128Argument(CI)) {
+    Module *M = B.GetInsertBlock()->getParent()->getParent();
+    auto SmallPrintFFn =
+        M->getOrInsertFunction(TLI->getName(LibFunc_small_printf),
+                               FT, Callee->getAttributes());
+    CallInst *New = cast<CallInst>(CI->clone());
+    New->setCalledFunction(SmallPrintFFn);
+    B.Insert(New);
+    return New;
+  }
+
   return nullptr;
 }
 
@@ -2131,6 +2151,20 @@ Value *LibCallSimplifier::optimizeSPrintF(CallInst *CI, IRBuilder<> &B) {
     B.Insert(New);
     return New;
   }
+
+  // sprintf(str, format, ...) -> __small_sprintf(str, format, ...) if no 128-bit
+  // floating point arguments.
+  if (TLI->has(LibFunc_small_sprintf) && !callHasFP128Argument(CI)) {
+    Module *M = B.GetInsertBlock()->getParent()->getParent();
+    auto SmallSPrintFFn =
+        M->getOrInsertFunction(TLI->getName(LibFunc_small_sprintf),
+                               FT, Callee->getAttributes());
+    CallInst *New = cast<CallInst>(CI->clone());
+    New->setCalledFunction(SmallSPrintFFn);
+    B.Insert(New);
+    return New;
+  }
+
   return nullptr;
 }
 
@@ -2288,6 +2322,20 @@ Value *LibCallSimplifier::optimizeFPrintF(CallInst *CI, IRBuilder<> &B) {
     B.Insert(New);
     return New;
   }
+
+  // fprintf(stream, format, ...) -> __small_fprintf(stream, format, ...) if no
+  // 128-bit floating point arguments.
+  if (TLI->has(LibFunc_small_fprintf) && !callHasFP128Argument(CI)) {
+    Module *M = B.GetInsertBlock()->getParent()->getParent();
+    auto SmallFPrintFFn =
+        M->getOrInsertFunction(TLI->getName(LibFunc_small_fprintf),
+                               FT, Callee->getAttributes());
+    CallInst *New = cast<CallInst>(CI->clone());
+    New->setCalledFunction(SmallFPrintFFn);
+    B.Insert(New);
+    return New;
+  }
+
   return nullptr;
 }