[PowerPC][X86] Make cpu id builtins target independent and lower for PPC (#68919)

Make __builtin_cpu_{init|supports|is} target independent and provide an
opt-in query for targets that want to support it. Each target is still
responsible for their specific lowering/code-gen. Also provide code-gen
for PowerPC.

I originally proposed this in https://reviews.llvm.org/D152914 and this
addresses the comments I received there.

---------

Co-authored-by: Nemanja Ivanovic <[email protected]>
Co-authored-by: Nemanja Ivanovic <[email protected]>

Author: 3 people

clang/include/clang/Basic/Builtins.td

@@ -727,6 +727,26 @@ def RotateRight : BitInt8_16_32_64BuiltinsTemplate, Builtin {
 // FIXME: The builtins marked FunctionWithBuiltinPrefix below should be
 //        merged with the library definitions. They are currently not because
 //        the attributes are different.
+
+// Builtins for checking CPU features based on the GCC builtins.
+def BuiltinCPUIs : Builtin {
+  let Spellings = ["__builtin_cpu_is"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "bool(char const*)";
+}
+
+def BuiltinCPUSupports : Builtin {
+  let Spellings = ["__builtin_cpu_supports"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "bool(char const*)";
+}
+
+def BuiltinCPUInit : Builtin {
+  let Spellings = ["__builtin_cpu_init"];
+  let Attributes = [NoThrow];
+  let Prototype = "void()";
+}
+
 def BuiltinCalloc : Builtin {
   let Spellings = ["__builtin_calloc"];
   let Attributes = [FunctionWithBuiltinPrefix, NoThrow];

clang/include/clang/Basic/BuiltinsX86.def

@@ -26,13 +26,6 @@
 #  define TARGET_HEADER_BUILTIN(ID, TYPE, ATTRS, HEADER, LANG, FEATURE) BUILTIN(ID, TYPE, ATTRS)
 #endif
 
-// Miscellaneous builtin for checking x86 cpu features.
-// TODO: Make this somewhat generic so that other backends
-// can use it?
-BUILTIN(__builtin_cpu_init, "v", "n")
-BUILTIN(__builtin_cpu_supports, "bcC*", "nc")
-BUILTIN(__builtin_cpu_is, "bcC*", "nc")
-
 // Undefined Values
 //
 TARGET_BUILTIN(__builtin_ia32_undef128, "V2d", "ncV:128:", "")

clang/include/clang/Basic/TargetInfo.h

@@ -1432,6 +1432,12 @@ class TargetInfo : public TransferrableTargetInfo,
             getTriple().isOSFreeBSD());
   }
 
+  // Identify whether this target supports __builtin_cpu_supports and
+  // __builtin_cpu_is.
+  virtual bool supportsCpuSupports() const { return false; }
+  virtual bool supportsCpuIs() const { return false; }
+  virtual bool supportsCpuInit() const { return false; }
+
   // Validate the contents of the __builtin_cpu_supports(const char*)
   // argument.
   virtual bool validateCpuSupports(StringRef Name) const { return false; }

clang/lib/Basic/Targets/PPC.cpp

@@ -903,3 +903,17 @@ ArrayRef<Builtin::Info> PPCTargetInfo::getTargetBuiltins() const {
   return llvm::ArrayRef(BuiltinInfo,
                         clang::PPC::LastTSBuiltin - Builtin::FirstTSBuiltin);
 }
+
+bool PPCTargetInfo::validateCpuSupports(StringRef FeatureStr) const {
+#define PPC_LNX_FEATURE(NAME, DESC, ENUMNAME, ENUMVAL, HWCAPN) .Case(NAME, true)
+  return llvm::StringSwitch<bool>(FeatureStr)
+#include "llvm/TargetParser/PPCTargetParser.def"
+      .Default(false);
+}
+
+bool PPCTargetInfo::validateCpuIs(StringRef CPUName) const {
+#define PPC_LNX_CPU(NAME, NUM) .Case(NAME, true)
+  return llvm::StringSwitch<bool>(CPUName)
+#include "llvm/TargetParser/PPCTargetParser.def"
+      .Default(false);
+}

clang/lib/Basic/Targets/PPC.h

@@ -359,6 +359,13 @@ class LLVM_LIBRARY_VISIBILITY PPCTargetInfo : public TargetInfo {
   bool isSPRegName(StringRef RegName) const override {
     return RegName.equals("r1") || RegName.equals("x1");
   }
+
+  // We support __builtin_cpu_supports/__builtin_cpu_is on targets that
+  // have Glibc since it is Glibc that provides the HWCAP[2] in the auxv.
+  bool supportsCpuSupports() const override { return getTriple().isOSGlibc(); }
+  bool supportsCpuIs() const override { return getTriple().isOSGlibc(); }
+  bool validateCpuSupports(StringRef Feature) const override;
+  bool validateCpuIs(StringRef Name) const override;
 };
 
 class LLVM_LIBRARY_VISIBILITY PPC32TargetInfo : public PPCTargetInfo {

clang/lib/Basic/Targets/X86.h

@@ -220,6 +220,10 @@ class LLVM_LIBRARY_VISIBILITY X86TargetInfo : public TargetInfo {
     return RegName.equals("esp") || RegName.equals("rsp");
   }
 
+  bool supportsCpuSupports() const override { return true; }
+  bool supportsCpuIs() const override { return true; }
+  bool supportsCpuInit() const override { return true; }
+
   bool validateCpuSupports(StringRef FeatureStr) const override;
 
   bool validateCpuIs(StringRef FeatureStr) const override;

clang/lib/CodeGen/CGBuiltin.cpp

@@ -14053,11 +14053,11 @@ CodeGenFunction::EmitAArch64CpuSupports(ArrayRef<StringRef> FeaturesStrs) {
 
 Value *CodeGenFunction::EmitX86BuiltinExpr(unsigned BuiltinID,
                                            const CallExpr *E) {
-  if (BuiltinID == X86::BI__builtin_cpu_is)
+  if (BuiltinID == Builtin::BI__builtin_cpu_is)
     return EmitX86CpuIs(E);
-  if (BuiltinID == X86::BI__builtin_cpu_supports)
+  if (BuiltinID == Builtin::BI__builtin_cpu_supports)
     return EmitX86CpuSupports(E);
-  if (BuiltinID == X86::BI__builtin_cpu_init)
+  if (BuiltinID == Builtin::BI__builtin_cpu_init)
     return EmitX86CpuInit();
 
   // Handle MSVC intrinsics before argument evaluation to prevent double
@@ -16545,6 +16545,43 @@ Value *CodeGenFunction::EmitPPCBuiltinExpr(unsigned BuiltinID,
   switch (BuiltinID) {
   default: return nullptr;
 
+  case Builtin::BI__builtin_cpu_is: {
+    const Expr *CPUExpr = E->getArg(0)->IgnoreParenCasts();
+    StringRef CPUStr = cast<clang::StringLiteral>(CPUExpr)->getString();
+    unsigned NumCPUID = StringSwitch<unsigned>(CPUStr)
+#define PPC_LNX_CPU(Name, NumericID) .Case(Name, NumericID)
+#include "llvm/TargetParser/PPCTargetParser.def"
+                            .Default(-1U);
+    assert(NumCPUID < -1U && "Invalid CPU name. Missed by SemaChecking?");
+    Value *Op0 = llvm::ConstantInt::get(Int32Ty, PPC_FAWORD_CPUID);
+    llvm::Function *F = CGM.getIntrinsic(Intrinsic::ppc_fixed_addr_ld);
+    Value *TheCall = Builder.CreateCall(F, {Op0}, "cpu_is");
+    return Builder.CreateICmpEQ(TheCall,
+                                llvm::ConstantInt::get(Int32Ty, NumCPUID));
+  }
+  case Builtin::BI__builtin_cpu_supports: {
+    unsigned FeatureWord;
+    unsigned BitMask;
+    const Expr *CPUExpr = E->getArg(0)->IgnoreParenCasts();
+    StringRef CPUStr = cast<clang::StringLiteral>(CPUExpr)->getString();
+    std::tie(FeatureWord, BitMask) =
+        StringSwitch<std::pair<unsigned, unsigned>>(CPUStr)
+#define PPC_LNX_FEATURE(Name, Description, EnumName, Bitmask, FA_WORD)         \
+  .Case(Name, {FA_WORD, Bitmask})
+#include "llvm/TargetParser/PPCTargetParser.def"
+            .Default({0, 0});
+    assert(BitMask && "Invalid target feature string. Missed by SemaChecking?");
+    Value *Op0 = llvm::ConstantInt::get(Int32Ty, FeatureWord);
+    llvm::Function *F = CGM.getIntrinsic(Intrinsic::ppc_fixed_addr_ld);
+    Value *TheCall = Builder.CreateCall(F, {Op0}, "cpu_supports");
+    Value *Mask =
+        Builder.CreateAnd(TheCall, llvm::ConstantInt::get(Int32Ty, BitMask));
+    return Builder.CreateICmpNE(Mask, llvm::Constant::getNullValue(Int32Ty));
+#undef PPC_FAWORD_HWCAP
+#undef PPC_FAWORD_HWCAP2
+#undef PPC_FAWORD_CPUID
+  }
+
   // __builtin_ppc_get_timebase is GCC 4.8+'s PowerPC-specific name for what we
   // call __builtin_readcyclecounter.
   case PPC::BI__builtin_ppc_get_timebase:

clang/lib/Sema/SemaChecking.cpp

@@ -2143,6 +2143,48 @@ static bool checkFPMathBuiltinElementType(Sema &S, SourceLocation Loc,
   return false;
 }
 
+/// SemaBuiltinCpu{Supports|Is} - Handle __builtin_cpu_{supports|is}(char *).
+/// This checks that the target supports the builtin and that the string
+/// argument is constant and valid.
+static bool SemaBuiltinCpu(Sema &S, const TargetInfo &TI, CallExpr *TheCall,
+                           const TargetInfo *AuxTI, unsigned BuiltinID) {
+  assert((BuiltinID == Builtin::BI__builtin_cpu_supports ||
+          BuiltinID == Builtin::BI__builtin_cpu_is) &&
+         "Expecting __builtin_cpu_...");
+
+  bool IsCPUSupports = BuiltinID == Builtin::BI__builtin_cpu_supports;
+  const TargetInfo *TheTI = &TI;
+  auto SupportsBI = [=](const TargetInfo *TInfo) {
+    return TInfo && ((IsCPUSupports && TInfo->supportsCpuSupports()) ||
+                     (!IsCPUSupports && TInfo->supportsCpuIs()));
+  };
+  if (!SupportsBI(&TI) && SupportsBI(AuxTI))
+    TheTI = AuxTI;
+
+  if (IsCPUSupports && !TheTI->supportsCpuSupports())
+    return S.Diag(TheCall->getBeginLoc(), diag::err_builtin_target_unsupported)
+           << SourceRange(TheCall->getBeginLoc(), TheCall->getEndLoc());
+  if (!IsCPUSupports && !TheTI->supportsCpuIs())
+    return S.Diag(TheCall->getBeginLoc(), diag::err_builtin_target_unsupported)
+           << SourceRange(TheCall->getBeginLoc(), TheCall->getEndLoc());
+
+  Expr *Arg = TheCall->getArg(0)->IgnoreParenImpCasts();
+  // Check if the argument is a string literal.
+  if (!isa<StringLiteral>(Arg))
+    return S.Diag(TheCall->getBeginLoc(), diag::err_expr_not_string_literal)
+           << Arg->getSourceRange();
+
+  // Check the contents of the string.
+  StringRef Feature = cast<StringLiteral>(Arg)->getString();
+  if (IsCPUSupports && !TheTI->validateCpuSupports(Feature))
+    return S.Diag(TheCall->getBeginLoc(), diag::err_invalid_cpu_supports)
+           << Arg->getSourceRange();
+  if (!IsCPUSupports && !TheTI->validateCpuIs(Feature))
+    return S.Diag(TheCall->getBeginLoc(), diag::err_invalid_cpu_is)
+           << Arg->getSourceRange();
+  return false;
+}
+
 ExprResult
 Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
                                CallExpr *TheCall) {
@@ -2171,6 +2213,19 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
 
   FPOptions FPO;
   switch (BuiltinID) {
+  case Builtin::BI__builtin_cpu_supports:
+  case Builtin::BI__builtin_cpu_is:
+    if (SemaBuiltinCpu(*this, Context.getTargetInfo(), TheCall,
+                       Context.getAuxTargetInfo(), BuiltinID))
+      return ExprError();
+    break;
+  case Builtin::BI__builtin_cpu_init:
+    if (!Context.getTargetInfo().supportsCpuInit()) {
+      Diag(TheCall->getBeginLoc(), diag::err_builtin_target_unsupported)
+          << SourceRange(TheCall->getBeginLoc(), TheCall->getEndLoc());
+      return ExprError();
+    }
+    break;
   case Builtin::BI__builtin___CFStringMakeConstantString:
     // CFStringMakeConstantString is currently not implemented for GOFF (i.e.,
     // on z/OS) and for XCOFF (i.e., on AIX). Emit unsupported
@@ -6216,47 +6271,6 @@ bool Sema::CheckNVPTXBuiltinFunctionCall(const TargetInfo &TI,
   return false;
 }
 
-/// SemaBuiltinCpuSupports - Handle __builtin_cpu_supports(char *).
-/// This checks that the target supports __builtin_cpu_supports and
-/// that the string argument is constant and valid.
-static bool SemaBuiltinCpuSupports(Sema &S, const TargetInfo &TI,
-                                   CallExpr *TheCall) {
-  Expr *Arg = TheCall->getArg(0);
-
-  // Check if the argument is a string literal.
-  if (!isa<StringLiteral>(Arg->IgnoreParenImpCasts()))
-    return S.Diag(TheCall->getBeginLoc(), diag::err_expr_not_string_literal)
-           << Arg->getSourceRange();
-
-  // Check the contents of the string.
-  StringRef Feature =
-      cast<StringLiteral>(Arg->IgnoreParenImpCasts())->getString();
-  if (!TI.validateCpuSupports(Feature))
-    return S.Diag(TheCall->getBeginLoc(), diag::err_invalid_cpu_supports)
-           << Arg->getSourceRange();
-  return false;
-}
-
-/// SemaBuiltinCpuIs - Handle __builtin_cpu_is(char *).
-/// This checks that the target supports __builtin_cpu_is and
-/// that the string argument is constant and valid.
-static bool SemaBuiltinCpuIs(Sema &S, const TargetInfo &TI, CallExpr *TheCall) {
-  Expr *Arg = TheCall->getArg(0);
-
-  // Check if the argument is a string literal.
-  if (!isa<StringLiteral>(Arg->IgnoreParenImpCasts()))
-    return S.Diag(TheCall->getBeginLoc(), diag::err_expr_not_string_literal)
-           << Arg->getSourceRange();
-
-  // Check the contents of the string.
-  StringRef Feature =
-      cast<StringLiteral>(Arg->IgnoreParenImpCasts())->getString();
-  if (!TI.validateCpuIs(Feature))
-    return S.Diag(TheCall->getBeginLoc(), diag::err_invalid_cpu_is)
-           << Arg->getSourceRange();
-  return false;
-}
-
 // Check if the rounding mode is legal.
 bool Sema::CheckX86BuiltinRoundingOrSAE(unsigned BuiltinID, CallExpr *TheCall) {
   // Indicates if this instruction has rounding control or just SAE.
@@ -6731,12 +6745,6 @@ static bool isX86_32Builtin(unsigned BuiltinID) {
 
 bool Sema::CheckX86BuiltinFunctionCall(const TargetInfo &TI, unsigned BuiltinID,
                                        CallExpr *TheCall) {
-  if (BuiltinID == X86::BI__builtin_cpu_supports)
-    return SemaBuiltinCpuSupports(*this, TI, TheCall);
-
-  if (BuiltinID == X86::BI__builtin_cpu_is)
-    return SemaBuiltinCpuIs(*this, TI, TheCall);
-
   // Check for 32-bit only builtins on a 64-bit target.
   const llvm::Triple &TT = TI.getTriple();
   if (TT.getArch() != llvm::Triple::x86 && isX86_32Builtin(BuiltinID))