Initial implementation for isfpclass and related builtins

Add lowering test

Author: badumbatish

clang/include/clang/CIR/Dialect/Builder/CIRBaseBuilder.h

@@ -442,6 +442,22 @@ class CIRBaseBuilderTy : public mlir::OpBuilder {
     return createCast(cir::CastKind::ptr_to_bool, v, getBoolTy());
   }
 
+  // TODO(cir): the following function was introduced to keep in sync with LLVM
+  // codegen. CIR does not have "zext" operations. It should eventually be
+  // renamed or removed. For now, we just add whatever cast is required here.
+  mlir::Value createZExtOrBitCast(mlir::Location loc, mlir::Value src,
+                                  mlir::Type newTy) {
+    auto srcTy = src.getType();
+
+    if (srcTy == newTy)
+      return src;
+
+    if (mlir::isa<cir::BoolType>(srcTy) && mlir::isa<cir::IntType>(newTy))
+      return createBoolToInt(src, newTy);
+
+    llvm_unreachable("unhandled extension cast");
+  }
+
   mlir::Value createBoolToInt(mlir::Value src, mlir::Type newTy) {
     return createCast(cir::CastKind::bool_to_int, src, newTy);
   }

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -3921,6 +3921,39 @@ def CIR_RotateOp : CIR_Op<"rotate", [Pure, SameOperandsAndResultType]> {
   let hasFolder = 1;
 }
 
+def CIR_IsFPClassOp : CIR_Op<"is_fp_class"> {
+  let summary = "Corresponding to the `__builtin_fpclassify` builtin function in clang";
+
+  let description = [{
+    The `cir.is_fp_class` operation takes a floating-point value as its first
+    argument and a bitfield of flags as its second argument. The operation
+    returns a boolean value indicating whether the floating-point value
+    satisfies the given flags.
+
+    The flags must be a compile time constant and the values are:
+
+    | Bit # | floating-point class |
+    | -------- | ------- |
+    | 0 | Signaling NaN      |
+    | 1 | Quiet NaN          |
+    | 2 | Negative infinity  |
+    | 3 | Negative normal    |
+    | 4 | Negative subnormal |
+    | 5 | Negative zero      |
+    | 6 | Positive zero      |
+    | 7 | Positive subnormal |
+    | 8 | Positive normal    |
+    | 9 | Positive infinity  |
+  }];
+
+  let arguments = (ins CIR_AnyFloatType:$src,
+                       I32Attr:$flags);
+  let results = (outs CIR_BoolType:$result);
+  let assemblyFormat = [{
+    $src `,` $flags `:` functional-type($src, $result) attr-dict
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // Assume Operations
 //===----------------------------------------------------------------------===//

clang/include/clang/CIR/Dialect/IR/FPEnv.h

@@ -0,0 +1,50 @@
+//===- FPEnv.h ---- FP Environment ------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// @file
+/// This file contains the declarations of entities that describe floating
+/// point environment and related functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_CIR_DIALECT_IR_FPENV_H
+#define CLANG_CIR_DIALECT_IR_FPENV_H
+
+#include "llvm/ADT/FloatingPointMode.h"
+
+#include <optional>
+
+namespace cir {
+
+namespace fp {
+
+/// Exception behavior used for floating point operations.
+///
+/// Each of these values corresponds to some LLVMIR metadata argument value of a
+/// constrained floating point intrinsic. See the LLVM Language Reference Manual
+/// for details.
+enum ExceptionBehavior : uint8_t {
+  ebIgnore,  ///< This corresponds to "fpexcept.ignore".
+  ebMayTrap, ///< This corresponds to "fpexcept.maytrap".
+  ebStrict,  ///< This corresponds to "fpexcept.strict".
+};
+
+} // namespace fp
+
+/// For any RoundingMode enumerator, returns a string valid as input in
+/// constrained intrinsic rounding mode metadata.
+std::optional<llvm::StringRef> convertRoundingModeToStr(llvm::RoundingMode);
+
+/// For any ExceptionBehavior enumerator, returns a string valid as input in
+/// constrained intrinsic exception behavior metadata.
+std::optional<llvm::StringRef>
+    convertExceptionBehaviorToStr(fp::ExceptionBehavior);
+
+} // namespace cir
+
+#endif

clang/include/clang/CIR/MissingFeatures.h

@@ -262,7 +262,10 @@ struct MissingFeatures {
   static bool emitNullabilityCheck() { return false; }
   static bool emitTypeCheck() { return false; }
   static bool emitTypeMetadataCodeForVCall() { return false; }
+  static bool fastMathGuard() { return false; }
   static bool fastMathFlags() { return false; }
+  static bool fastMathFuncAttributes() { return false; }
+
   static bool fpConstraints() { return false; }
   static bool generateDebugInfo() { return false; }
   static bool globalViewIndices() { return false; }

clang/lib/CIR/CodeGen/CIRGenBuilder.h

@@ -16,6 +16,7 @@
 #include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/Support/LLVM.h"
 #include "clang/CIR/Dialect/IR/CIRDataLayout.h"
+#include "clang/CIR/Dialect/IR/FPEnv.h"
 #include "clang/CIR/MissingFeatures.h"
 
 #include "clang/CIR/Dialect/Builder/CIRBaseBuilder.h"
@@ -29,6 +30,9 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
   const CIRGenTypeCache &typeCache;
   llvm::StringMap<unsigned> recordNames;
   llvm::StringMap<unsigned> globalsVersioning;
+  bool isFpConstrained = false;
+  cir::fp::ExceptionBehavior defaultConstrainedExcept = cir::fp::ebStrict;
+  llvm::RoundingMode defaultConstrainedRounding = llvm::RoundingMode::Dynamic;
 
 public:
   CIRGenBuilderTy(mlir::MLIRContext &mlirContext, const CIRGenTypeCache &tc)
@@ -66,6 +70,56 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
                                     cir::ArrayType arrayTy) const {
     return cir::ConstArrayAttr::get(arrayTy, attrs);
   }
+  //
+  // Floating point specific helpers
+  // -------------------------------
+  //
+
+  /// Enable/Disable use of constrained floating point math. When enabled the
+  /// CreateF<op>() calls instead create constrained floating point intrinsic
+  /// calls. Fast math flags are unaffected by this setting.
+  void setIsFPConstrained(bool isCon) {
+    if (isCon)
+      llvm_unreachable("Constrained FP NYI");
+    isFpConstrained = isCon;
+  }
+
+  /// Query for the use of constrained floating point math
+  bool getIsFPConstrained() {
+    if (isFpConstrained)
+      llvm_unreachable("Constrained FP NYI");
+    return isFpConstrained;
+  }
+  ///
+  /// Set the exception handling to be used with constrained floating point
+  void setDefaultConstrainedExcept(cir::fp::ExceptionBehavior newExcept) {
+#ifndef NDEBUG
+    std::optional<llvm::StringRef> exceptStr =
+        cir::convertExceptionBehaviorToStr(newExcept);
+    assert(exceptStr && "Garbage strict exception behavior!");
+#endif
+    defaultConstrainedExcept = newExcept;
+  }
+
+  /// Set the rounding mode handling to be used with constrained floating point
+  void setDefaultConstrainedRounding(llvm::RoundingMode newRounding) {
+#ifndef NDEBUG
+    std::optional<llvm::StringRef> roundingStr =
+        cir::convertRoundingModeToStr(newRounding);
+    assert(roundingStr && "Garbage strict rounding mode!");
+#endif
+    defaultConstrainedRounding = newRounding;
+  }
+
+  /// Get the exception handling used with constrained floating point
+  cir::fp::ExceptionBehavior getDefaultConstrainedExcept() {
+    return defaultConstrainedExcept;
+  }
+
+  /// Get the rounding mode handling used with constrained floating point
+  llvm::RoundingMode getDefaultConstrainedRounding() {
+    return defaultConstrainedRounding;
+  }
 
   mlir::Attribute getConstRecordOrZeroAttr(mlir::ArrayAttr arrayAttr,
                                            bool packed = false,
@@ -332,6 +386,11 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
     llvm_unreachable("negation for the given type is NYI");
   }
 
+  cir::IsFPClassOp createIsFPClass(mlir::Location loc, mlir::Value src,
+                                   unsigned flags) {
+    return cir::IsFPClassOp::create(*this, loc, src, flags);
+  }
+
   // TODO: split this to createFPExt/createFPTrunc when we have dedicated cast
   // operations.
   mlir::Value createFloatingCast(mlir::Value v, mlir::Type destType) {

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -29,6 +29,16 @@ using namespace clang;
 using namespace clang::CIRGen;
 using namespace llvm;
 
+static mlir::Value tryUseTestFPKind(CIRGenFunction &cgf, unsigned BuiltinID,
+                                    mlir::Value V) {
+  if (cgf.getBuilder().getIsFPConstrained() &&
+      cgf.getBuilder().getDefaultConstrainedExcept() != cir::fp::ebIgnore) {
+    if (mlir::Value Result = cgf.getTargetHooks().testFPKind(
+            V, BuiltinID, cgf.getBuilder(), cgf.cgm))
+      return Result;
+  }
+  return nullptr;
+}
 static RValue emitLibraryCall(CIRGenFunction &cgf, const FunctionDecl *fd,
                               const CallExpr *e, mlir::Operation *calleeValue) {
   CIRGenCallee callee = CIRGenCallee::forDirect(calleeValue, GlobalDecl(fd));
@@ -515,14 +525,117 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
     cir::PrefetchOp::create(builder, loc, address, locality, isWrite);
     return RValue::get(nullptr);
   }
+  // From https://clang.llvm.org/docs/LanguageExtensions.html#builtin-isfpclass
+  // :
+  //
+  //  The `__builtin_isfpclass()` builtin is a generalization of functions
+  //  isnan, isinf, isfinite and some others defined by the C standard. It tests
+  //  if the floating-point value, specified by the first argument, falls into
+  //  any of data classes, specified by the second argument.
+  case Builtin::BI__builtin_isnan: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    if (mlir::Value result = tryUseTestFPKind(*this, builtinID, v))
+      return RValue::get(result);
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcNan),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_issignaling: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcSNan),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_isinf: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    if (mlir::Value result = tryUseTestFPKind(*this, builtinID, v))
+      return RValue::get(result);
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcInf),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BIfinite:
+  case Builtin::BI__finite:
+  case Builtin::BIfinitef:
+  case Builtin::BI__finitef:
+  case Builtin::BIfinitel:
+  case Builtin::BI__finitel:
+  case Builtin::BI__builtin_isfinite: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    if (mlir::Value result = tryUseTestFPKind(*this, builtinID, v))
+      return RValue::get(result);
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcFinite),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_isnormal: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcNormal),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_issubnormal: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcSubnormal),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_iszero: {
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, FPClassTest::fcZero),
+        convertType(e->getType())));
+  }
+  case Builtin::BI__builtin_isfpclass: {
+    Expr::EvalResult result;
+    if (!e->getArg(1)->EvaluateAsInt(result, cgm.getASTContext()))
+      break;
+
+    CIRGenFunction::CIRGenFPOptionsRAII fpOptsRaii(*this, e);
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    uint64_t test = result.Val.getInt().getLimitedValue();
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    //
+    // // FIXME: We should use builder.createZExt once createZExt is available.
+    return RValue::get(builder.createZExtOrBitCast(
+        loc, builder.createIsFPClass(loc, v, test), convertType(e->getType())));
+  }
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit
   // the call using the normal call path, but using the unmangled
   // version of the function name.
-  if (getContext().BuiltinInfo.isLibFunction(builtinID))
+  if (getContext().BuiltinInfo.isLibFunction(builtinID)) {
     return emitLibraryCall(*this, fd, e,
                            cgm.getBuiltinLibFunction(fd, builtinID));
+  }
 
   // Some target-specific builtins can have aggregate return values, e.g.
   // __builtin_arm_mve_vld2q_u32. So if the result is an aggregate, force