Make System.Math/MathF.Truncate an intrinsic (#65014)

src/coreclr/jit/codegenarmarch.cpp

@@ -622,7 +622,7 @@ void CodeGen::genIntrinsic(GenTree* treeNode)
     assert(varTypeIsFloating(srcNode));
     assert(srcNode->TypeGet() == treeNode->TypeGet());
 
-    // Right now only Abs/Ceiling/Floor/Round/Sqrt are treated as math intrinsics.
+    // Right now only Abs/Ceiling/Floor/Truncate/Round/Sqrt are treated as math intrinsics.
     //
     switch (treeNode->AsIntrinsic()->gtIntrinsicName)
     {
@@ -642,6 +642,11 @@ void CodeGen::genIntrinsic(GenTree* treeNode)
             GetEmitter()->emitInsBinary(INS_frintm, emitActualTypeSize(treeNode), treeNode, srcNode);
             break;
 
+        case NI_System_Math_Truncate:
+            genConsumeOperands(treeNode->AsOp());
+            GetEmitter()->emitInsBinary(INS_frintz, emitActualTypeSize(treeNode), treeNode, srcNode);
+            break;
+
         case NI_System_Math_Round:
             genConsumeOperands(treeNode->AsOp());
             GetEmitter()->emitInsBinary(INS_frintn, emitActualTypeSize(treeNode), treeNode, srcNode);

src/coreclr/jit/codegenxarch.cpp

@@ -7027,7 +7027,7 @@ void CodeGen::genSSE2BitwiseOp(GenTree* treeNode)
 //    ii) treeNode oper is a GT_INTRINSIC
 //   iii) treeNode type is a floating point type
 //    iv) treeNode is not used from memory
-//     v) tree oper is NI_System_Math{F}_Round, _Ceiling, or _Floor
+//     v) tree oper is NI_System_Math{F}_Round, _Ceiling, _Floor, or _Truncate
 //    vi) caller of this routine needs to call genProduceReg()
 void CodeGen::genSSE41RoundOp(GenTreeOp* treeNode)
 {
@@ -7055,7 +7055,7 @@ void CodeGen::genSSE41RoundOp(GenTreeOp* treeNode)
 
     unsigned ival = 0;
 
-    // v) tree oper is NI_System_Math{F}_Round, _Ceiling, or _Floor
+    // v) tree oper is NI_System_Math{F}_Round, _Ceiling, _Floor, or _Truncate
     switch (treeNode->AsIntrinsic()->gtIntrinsicName)
     {
         case NI_System_Math_Round:
@@ -7070,6 +7070,10 @@ void CodeGen::genSSE41RoundOp(GenTreeOp* treeNode)
             ival = 9;
             break;
 
+        case NI_System_Math_Truncate:
+            ival = 11;
+            break;
+
         default:
             ins = INS_invalid;
             assert(!"genSSE41RoundOp: unsupported intrinsic");
@@ -7197,6 +7201,7 @@ void CodeGen::genIntrinsic(GenTree* treeNode)
 
         case NI_System_Math_Ceiling:
         case NI_System_Math_Floor:
+        case NI_System_Math_Truncate:
         case NI_System_Math_Round:
             genSSE41RoundOp(treeNode->AsOp());
             break;

src/coreclr/jit/gentree.cpp

@@ -3862,6 +3862,7 @@ unsigned Compiler::gtSetEvalOrder(GenTree* tree)
                         case NI_System_Math_Sqrt:
                         case NI_System_Math_Tan:
                         case NI_System_Math_Tanh:
+                        case NI_System_Math_Truncate:
                         {
                             // Giving intrinsics a large fixed execution cost is because we'd like to CSE
                             // them, even if they are implemented by calls. This is different from modeling
@@ -10891,6 +10892,9 @@ void Compiler::gtDispTree(GenTree*     tree,
                 case NI_System_Math_Tanh:
                     printf(" tanh");
                     break;
+                case NI_System_Math_Truncate:
+                    printf(" truncate");
+                    break;
                 case NI_System_Object_GetType:
                     printf(" objGetType");
                     break;

src/coreclr/jit/importer.cpp

@@ -4447,6 +4447,7 @@ GenTree* Compiler::impIntrinsic(GenTree*                newobjThis,
             case NI_System_Math_Sqrt:
             case NI_System_Math_Tan:
             case NI_System_Math_Tanh:
+            case NI_System_Math_Truncate:
             {
                 retNode = impMathIntrinsic(method, sig, callType, ni, tailCall);
                 break;
@@ -5093,6 +5094,10 @@ NamedIntrinsic Compiler::lookupNamedIntrinsic(CORINFO_METHOD_HANDLE method)
             {
                 result = NI_System_Math_Tanh;
             }
+            else if (strcmp(methodName, "Truncate") == 0)
+            {
+                result = NI_System_Math_Truncate;
+            }
         }
         else if (strcmp(className, "GC") == 0)
         {
@@ -20448,14 +20453,15 @@ bool Compiler::IsTargetIntrinsic(NamedIntrinsic intrinsicName)
     switch (intrinsicName)
     {
         // AMD64/x86 has SSE2 instructions to directly compute sqrt/abs and SSE4.1
-        // instructions to directly compute round/ceiling/floor.
+        // instructions to directly compute round/ceiling/floor/truncate.
 
         case NI_System_Math_Abs:
         case NI_System_Math_Sqrt:
             return true;
 
         case NI_System_Math_Ceiling:
         case NI_System_Math_Floor:
+        case NI_System_Math_Truncate:
         case NI_System_Math_Round:
             return compOpportunisticallyDependsOn(InstructionSet_SSE41);
 
@@ -20471,6 +20477,7 @@ bool Compiler::IsTargetIntrinsic(NamedIntrinsic intrinsicName)
         case NI_System_Math_Abs:
         case NI_System_Math_Ceiling:
         case NI_System_Math_Floor:
+        case NI_System_Math_Truncate:
         case NI_System_Math_Round:
         case NI_System_Math_Sqrt:
             return true;
@@ -20544,6 +20551,7 @@ bool Compiler::IsMathIntrinsic(NamedIntrinsic intrinsicName)
         case NI_System_Math_Sqrt:
         case NI_System_Math_Tan:
         case NI_System_Math_Tanh:
+        case NI_System_Math_Truncate:
         {
             assert((intrinsicName > NI_SYSTEM_MATH_START) && (intrinsicName < NI_SYSTEM_MATH_END));
             return true;

src/coreclr/jit/lowerxarch.cpp

@@ -5275,7 +5275,8 @@ void Lowering::ContainCheckIntrinsic(GenTreeOp* node)
     NamedIntrinsic intrinsicName = node->AsIntrinsic()->gtIntrinsicName;
 
     if ((intrinsicName == NI_System_Math_Ceiling) || (intrinsicName == NI_System_Math_Floor) ||
-        (intrinsicName == NI_System_Math_Round) || (intrinsicName == NI_System_Math_Sqrt))
+        (intrinsicName == NI_System_Math_Truncate) || (intrinsicName == NI_System_Math_Round) ||
+        (intrinsicName == NI_System_Math_Sqrt))
     {
         GenTree* op1 = node->gtGetOp1();
 

src/coreclr/jit/lsraarm64.cpp

@@ -329,6 +329,7 @@ int LinearScan::BuildNode(GenTree* tree)
             noway_assert((tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Abs) ||
                          (tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Ceiling) ||
                          (tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Floor) ||
+                         (tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Truncate) ||
                          (tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Round) ||
                          (tree->AsIntrinsic()->gtIntrinsicName == NI_System_Math_Sqrt));
 

src/coreclr/jit/lsraxarch.cpp

@@ -1826,6 +1826,7 @@ int LinearScan::BuildIntrinsic(GenTree* tree)
 
         case NI_System_Math_Ceiling:
         case NI_System_Math_Floor:
+        case NI_System_Math_Truncate:
         case NI_System_Math_Round:
         case NI_System_Math_Sqrt:
             break;

src/coreclr/jit/namedintrinsiclist.h

@@ -43,6 +43,7 @@ enum NamedIntrinsic : unsigned short
     NI_System_Math_Sqrt,
     NI_System_Math_Tan,
     NI_System_Math_Tanh,
+    NI_System_Math_Truncate,
     NI_SYSTEM_MATH_END,
 
     NI_System_Collections_Generic_Comparer_get_Default,

src/coreclr/jit/valuenum.cpp

@@ -5294,6 +5294,10 @@ ValueNum ValueNumStore::EvalMathFuncUnary(var_types typ, NamedIntrinsic gtMathFN
                     res = tanh(arg0Val);
                     break;
 
+                case NI_System_Math_Truncate:
+                    res = trunc(arg0Val);
+                    break;
+
                 default:
                     // the above are the only math intrinsics at the time of this writing.
                     unreached();
@@ -5398,6 +5402,10 @@ ValueNum ValueNumStore::EvalMathFuncUnary(var_types typ, NamedIntrinsic gtMathFN
                     res = tanhf(arg0Val);
                     break;
 
+                case NI_System_Math_Truncate:
+                    res = truncf(arg0Val);
+                    break;
+
                 default:
                     // the above are the only math intrinsics at the time of this writing.
                     unreached();
@@ -5552,6 +5560,9 @@ ValueNum ValueNumStore::EvalMathFuncUnary(var_types typ, NamedIntrinsic gtMathFN
             case NI_System_Math_Tanh:
                 vnf = VNF_Tanh;
                 break;
+            case NI_System_Math_Truncate:
+                vnf = VNF_Truncate;
+                break;
             default:
                 unreached(); // the above are the only math intrinsics at the time of this writing.
         }

src/coreclr/jit/valuenumfuncs.h

@@ -101,6 +101,7 @@ ValueNumFuncDef(Sinh, 1, false, false, false)
 ValueNumFuncDef(Sqrt, 1, false, false, false)
 ValueNumFuncDef(Tan, 1, false, false, false)
 ValueNumFuncDef(Tanh, 1, false, false, false)
+ValueNumFuncDef(Truncate, 1, false, false, false)
 
 ValueNumFuncDef(ManagedThreadId, 0, false, false, false)
 

src/coreclr/pal/inc/pal.h

@@ -4222,6 +4222,7 @@ PALIMPORT double __cdecl sinh(double);
 PALIMPORT double __cdecl sqrt(double);
 PALIMPORT double __cdecl tan(double);
 PALIMPORT double __cdecl tanh(double);
+PALIMPORT double __cdecl trunc(double);
 
 PALIMPORT int __cdecl _finitef(float);
 PALIMPORT int __cdecl _isnanf(float);
@@ -4254,6 +4255,7 @@ PALIMPORT float __cdecl sinhf(float);
 PALIMPORT float __cdecl sqrtf(float);
 PALIMPORT float __cdecl tanf(float);
 PALIMPORT float __cdecl tanhf(float);
+PALIMPORT float __cdecl truncf(float);
 #endif // !PAL_STDCPP_COMPAT
 
 #ifndef PAL_STDCPP_COMPAT

src/coreclr/pal/src/include/pal/palinternal.h

@@ -221,6 +221,7 @@ function_name() to call the system's implementation
 #define sqrt DUMMY_sqrt
 #define tan DUMMY_tan
 #define tanh DUMMY_tanh
+#define trunc DUMMY_trunc
 #define ceilf DUMMY_ceilf
 #define cosf DUMMY_cosf
 #define coshf DUMMY_coshf
@@ -233,6 +234,7 @@ function_name() to call the system's implementation
 #define sqrtf DUMMY_sqrtf
 #define tanf DUMMY_tanf
 #define tanhf DUMMY_tanhf
+#define truncf DUMMY_truncf
 
 /* RAND_MAX needed to be renamed to avoid duplicate definition when including
    stdlib.h header files. PAL_RAND_MAX should have the same value as RAND_MAX
@@ -464,6 +466,7 @@ function_name() to call the system's implementation
 #undef sqrt
 #undef tan
 #undef tanh
+#undef trunc
 #undef acosf
 #undef acoshf
 #undef asinf
@@ -492,6 +495,7 @@ function_name() to call the system's implementation
 #undef sqrtf
 #undef tanf
 #undef tanhf
+#undef truncf
 #undef rand
 #undef srand
 #undef errno

src/libraries/System.Private.CoreLib/src/System/Math.cs

@@ -1452,6 +1452,7 @@ public static decimal Truncate(decimal d)
             return decimal.Truncate(d);
         }
 
+        [Intrinsic]
         public static unsafe double Truncate(double d)
         {
             ModF(d, &d);

src/libraries/System.Private.CoreLib/src/System/MathF.cs

@@ -508,6 +508,7 @@ public static int Sign(float x)
             return Math.Sign(x);
         }
 
+        [Intrinsic]
         public static unsafe float Truncate(float x)
         {
             ModF(x, &x);