Author: Jasmine Tang
Date: 2025-11-19T15:52:51-08:00
New Revision: 1278d47e9f9773972ff17deaf4d69db48dccdad8

URL: 
https://github.com/llvm/llvm-project/commit/1278d47e9f9773972ff17deaf4d69db48dccdad8
DIFF: 
https://github.com/llvm/llvm-project/commit/1278d47e9f9773972ff17deaf4d69db48dccdad8.diff

LOG: [CIR] Upstream isfpclass op (#166037)

Ref commit in incubator: ee17ff67f3e567585db991cdad1159520c516bb4
 
There is a minor change in the assumption for emitting a direct callee.
In incubator, `bool hasAttributeNoBuiltin = false`
(`llvm-project/clang/lib/CIR/CodeGen/CIRGenExpr.cpp:1671`), while in
upstream, it's true, therefore, the call to finite(...) is not converted
to a builtin anymore.

Fixes #163892

Added: 
    clang/test/CIR/CodeGen/builtin-isfpclass.c

Modified: 
    clang/include/clang/CIR/Dialect/IR/CIROps.td
    clang/include/clang/CIR/MissingFeatures.h
    clang/lib/CIR/CodeGen/CIRGenBuilder.h
    clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
    clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td 
b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 92300ef5b152c..79a1b292df462 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -4112,6 +4112,72 @@ def CIR_RotateOp : CIR_Op<"rotate", [Pure, 
SameOperandsAndResultType]> {
   let hasFolder = 1;
 }
 
+//===----------------------------------------------------------------------===//
+// FPClass Test Flags
+//===----------------------------------------------------------------------===//
+
+def FPClassTestEnum : CIR_I32EnumAttr<"FPClassTest", "floating-point class 
test flags", [
+  // Basic flags
+  I32EnumAttrCase<"SignalingNaN", 1, "fcSNan">,
+  I32EnumAttrCase<"QuietNaN", 2, "fcQNan">,
+  I32EnumAttrCase<"NegativeInfinity", 4, "fcNegInf">,
+  I32EnumAttrCase<"NegativeNormal", 8, "fcNegNormal">,
+  I32EnumAttrCase<"NegativeSubnormal", 16, "fcNegSubnormal">,
+  I32EnumAttrCase<"NegativeZero", 32, "fcNegZero">,
+  I32EnumAttrCase<"PositiveZero", 64, "fcPosZero">,
+  I32EnumAttrCase<"PositiveSubnormal", 128, "fcPosSubnormal">,
+  I32EnumAttrCase<"PositiveNormal", 256, "fcPosNormal">,
+  I32EnumAttrCase<"PositiveInfinity", 512, "fcPosInf">,
+
+  // Composite flags
+  I32EnumAttrCase<"Nan", 3, "fcNan">,                   // fcSNan | fcQNan
+  I32EnumAttrCase<"Infinity", 516, "fcInf">,            // fcPosInf | fcNegInf
+  I32EnumAttrCase<"Normal", 264, "fcNormal">,           // fcPosNormal | 
fcNegNormal
+  I32EnumAttrCase<"Subnormal", 144, "fcSubnormal">,     // fcPosSubnormal | 
fcNegSubnormal
+  I32EnumAttrCase<"Zero", 96, "fcZero">,                // fcPosZero | 
fcNegZero
+  I32EnumAttrCase<"PositiveFinite", 448, "fcPosFinite">,// fcPosNormal | 
fcPosSubnormal | fcPosZero
+  I32EnumAttrCase<"NegativeFinite", 56, "fcNegFinite">, // fcNegNormal | 
fcNegSubnormal | fcNegZero
+  I32EnumAttrCase<"Finite", 504, "fcFinite">,           // fcPosFinite | 
fcNegFinite
+  I32EnumAttrCase<"Positive", 960, "fcPositive">,       // fcPosFinite | 
fcPosInf
+  I32EnumAttrCase<"Negative", 60, "fcNegative">,        // fcNegFinite | 
fcNegInf
+  I32EnumAttrCase<"All", 1023, "fcAllFlags">,           // fcNan | fcInf | 
fcFinite
+]> {
+  let cppNamespace = "::cir";
+}
+
+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:$src,
+                       FPClassTestEnum:$flags);
+  let results = (outs CIR_BoolType:$result);
+  let assemblyFormat = [{
+    $src `,` $flags `:` functional-type($src, $result) attr-dict
+  }];
+}
+
 
//===----------------------------------------------------------------------===//
 // Assume Operations
 
//===----------------------------------------------------------------------===//

diff  --git a/clang/include/clang/CIR/MissingFeatures.h 
b/clang/include/clang/CIR/MissingFeatures.h
index 6b5c34d28ce2a..2ecde9aa5d56d 100644
--- a/clang/include/clang/CIR/MissingFeatures.h
+++ b/clang/include/clang/CIR/MissingFeatures.h
@@ -266,6 +266,7 @@ struct MissingFeatures {
   static bool emitTypeCheck() { return false; }
   static bool emitTypeMetadataCodeForVCall() { return false; }
   static bool fastMathFlags() { return false; }
+
   static bool fpConstraints() { return false; }
   static bool generateDebugInfo() { return false; }
   static bool globalViewIndices() { return false; }

diff  --git a/clang/lib/CIR/CodeGen/CIRGenBuilder.h 
b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
index 653ce00b29d36..85b38120169fd 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuilder.h
+++ b/clang/lib/CIR/CodeGen/CIRGenBuilder.h
@@ -344,6 +344,11 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
     llvm_unreachable("negation for the given type is NYI");
   }
 
+  cir::IsFPClassOp createIsFPClass(mlir::Location loc, mlir::Value src,
+                                   cir::FPClassTest 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) {

diff  --git a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp 
b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
index 77f19343653db..dee5704c66011 100644
--- a/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp
@@ -520,6 +520,98 @@ 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: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    assert(!cir::MissingFeatures::fpConstraints());
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Nan),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_issignaling: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::SignalingNaN),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_isinf: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    assert(!cir::MissingFeatures::fpConstraints());
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Infinity),
+        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: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    assert(!cir::MissingFeatures::fpConstraints());
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Finite),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_isnormal: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Normal),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_issubnormal: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Subnormal),
+        convertType(e->getType())));
+  }
+
+  case Builtin::BI__builtin_iszero: {
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest::Zero),
+        convertType(e->getType())));
+  }
+  case Builtin::BI__builtin_isfpclass: {
+    Expr::EvalResult result;
+    if (!e->getArg(1)->EvaluateAsInt(result, cgm.getASTContext()))
+      break;
+
+    assert(!cir::MissingFeatures::cgFPOptionsRAII());
+    mlir::Value v = emitScalarExpr(e->getArg(0));
+    uint64_t test = result.Val.getInt().getLimitedValue();
+    mlir::Location loc = getLoc(e->getBeginLoc());
+    //
+    return RValue::get(builder.createBoolToInt(
+        builder.createIsFPClass(loc, v, cir::FPClassTest(test)),
+        convertType(e->getType())));
+  }
   }
 
   // If this is an alias for a lib function (e.g. __builtin_sin), emit

diff  --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp 
b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
index d45a2975c4afc..833464824f0e5 100644
--- a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
+++ b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -676,6 +676,18 @@ mlir::LogicalResult 
CIRToLLVMASinOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMIsFPClassOpLowering::matchAndRewrite(
+    cir::IsFPClassOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  mlir::Value src = adaptor.getSrc();
+  cir::FPClassTest flags = adaptor.getFlags();
+  mlir::IntegerType retTy = rewriter.getI1Type();
+
+  rewriter.replaceOpWithNewOp<mlir::LLVM::IsFPClass>(
+      op, retTy, src, static_cast<uint32_t>(flags));
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMAssumeOpLowering::matchAndRewrite(
     cir::AssumeOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {

diff  --git a/clang/test/CIR/CodeGen/builtin-isfpclass.c 
b/clang/test/CIR/CodeGen/builtin-isfpclass.c
new file mode 100644
index 0000000000000..16d82c905f445
--- /dev/null
+++ b/clang/test/CIR/CodeGen/builtin-isfpclass.c
@@ -0,0 +1,174 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o 
%t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o 
%t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=OGCG
+int finite(double);
+
+// CHECK: cir.func {{.*}}@test_is_finite
+void test_is_finite(__fp16 *H, float F, double D, long double LD) {
+    volatile int res;
+    res = __builtin_isinf(*H);
+    // CIR: cir.is_fp_class %{{.*}}, fcInf : (!cir.f16) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 516)
+    // OGCG: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 516)
+
+    res = __builtin_isinf(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcInf : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 516)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 516)
+
+    res = __builtin_isinf(D);
+    // CIR: cir.is_fp_class %{{.*}}, fcInf : (!cir.double) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f64(double {{.*}}, i32 516)
+    // OGCG: call i1 @llvm.is.fpclass.f64(double {{.*}}, i32 516)
+
+    res = __builtin_isinf(LD);
+    // CIR: cir.is_fp_class %{{.*}}, fcInf : (!cir.long_double<!cir.f80>) -> 
!cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f80(x86_fp80 {{.*}}, i32 516)
+    // OGCG: call i1 @llvm.is.fpclass.f80(x86_fp80 {{.*}}, i32 516)
+
+    res = __builtin_isfinite(*H);
+    // CIR: cir.is_fp_class %{{.*}}, fcFinite : (!cir.f16) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 504)
+    // OGCG: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 504)
+
+    res = __builtin_isfinite(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcFinite : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 504)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 504)
+
+    res = finite(D);
+    // CIR: cir.call @finite(%{{.*}}) nothrow side_effect(const) : 
(!cir.double) -> !s32i
+    // LLVM: call i32 @finite(double {{.*}})
+    // OGCG: call i1 @llvm.is.fpclass.f64(double %20, i32 504)
+    res = __builtin_isnormal(*H);
+    // CIR: cir.is_fp_class %{{.*}}, fcNormal : (!cir.f16) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 264)
+    // OGCG: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 264)
+
+    res = __builtin_isnormal(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcNormal : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 264)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 264)
+
+    res = __builtin_issubnormal(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcSubnormal : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 144)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 144)
+    res = __builtin_iszero(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcZero : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 96)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 96)
+    res = __builtin_issignaling(F);
+    // CIR: cir.is_fp_class %{{.*}}, fcSNan : (!cir.float) -> !cir.bool
+    // LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 1)
+    // OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 1)
+}
+
+_Bool check_isfpclass_finite(float x) {
+  return __builtin_isfpclass(x, 504 /*Finite*/);
+}
+
+// CIR: cir.func {{.*}}@check_isfpclass_finite
+// CIR: cir.is_fp_class %{{.*}}, fcFinite : (!cir.float)
+// LLVM: @check_isfpclass_finite
+// LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 504)
+// OGCG: @check_isfpclass_finite
+// OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 504)
+
+_Bool check_isfpclass_nan_f32(float x) {
+  return __builtin_isfpclass(x, 3 /*NaN*/);
+}
+
+// CIR: cir.func {{.*}}@check_isfpclass_nan_f32
+// CIR: cir.is_fp_class %{{.*}}, fcNan : (!cir.float)
+// LLVM: @check_isfpclass_nan_f32
+// LLVM: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 3)
+// OGCG: @check_isfpclass_nan_f32
+// OGCG: call i1 @llvm.is.fpclass.f32(float {{.*}}, i32 3)
+
+
+_Bool check_isfpclass_snan_f64(double x) {
+  return __builtin_isfpclass(x, 1 /*SNaN*/);
+}
+
+// CIR: cir.func {{.*}}@check_isfpclass_snan_f64
+// CIR: cir.is_fp_class %{{.*}}, fcSNan : (!cir.double)
+// LLVM: @check_isfpclass_snan_f64
+// LLVM: call i1 @llvm.is.fpclass.f64(double {{.*}}, i32 1)
+// OGCG: @check_isfpclass_snan_f64
+// OGCG: call i1 @llvm.is.fpclass.f64(double {{.*}}, i32 1)
+
+
+_Bool check_isfpclass_zero_f16(_Float16 x) {
+  return __builtin_isfpclass(x, 96 /*Zero*/);
+}
+
+// CIR: cir.func {{.*}}@check_isfpclass_zero_f16
+// CIR: cir.is_fp_class %{{.*}}, fcZero : (!cir.f16)
+// LLVM: @check_isfpclass_zero_f16
+// LLVM: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 96)
+// OGCG: @check_isfpclass_zero_f16
+// OGCG: call i1 @llvm.is.fpclass.f16(half {{.*}}, i32 96)
+
+// Update when we support FP pragma in functions and can convert BoolType in 
prvalue to i1.
+
+// _Bool check_isfpclass_finite_strict(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfpclass(x, 504 /*Finite*/);
+// }
+// 
+// _Bool check_isfpclass_nan_f32_strict(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfpclass(x, 3 /*NaN*/);
+// }
+// 
+// _Bool check_isfpclass_snan_f64_strict(double x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfpclass(x, 1 /*NaN*/);
+// }
+// 
+// _Bool check_isfpclass_zero_f16_strict(_Float16 x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfpclass(x, 96 /*Zero*/);
+// }
+// 
+// _Bool check_isnan(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isnan(x);
+// }
+// 
+// _Bool check_isinf(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isinf(x);
+// }
+// 
+// _Bool check_isfinite(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfinite(x);
+// }
+// 
+// _Bool check_isnormal(float x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isnormal(x);
+// }
+// 
+// typedef float __attribute__((ext_vector_type(4))) float4;
+// typedef double __attribute__((ext_vector_type(4))) double4;
+// typedef int __attribute__((ext_vector_type(4))) int4;
+// typedef long __attribute__((ext_vector_type(4))) long4;
+// 
+// int4 check_isfpclass_nan_v4f32(float4 x) {
+//   return __builtin_isfpclass(x, 3 /*NaN*/);
+// }
+// 
+// int4 check_isfpclass_nan_strict_v4f32(float4 x) {
+// #pragma STDC FENV_ACCESS ON
+//   return __builtin_isfpclass(x, 3 /*NaN*/);
+// }
+// 
+// long4 check_isfpclass_nan_v4f64(double4 x) {
+//   return __builtin_isfpclass(x, 3 /*NaN*/);
+// }


        
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