JIT: Use new ABI classifiers for GenTreeCall arguments (#103537)

Switch `AddFinalArgsAndDetermineABIInfo` to reuse the new-style ABI classifiers.

Does not remove the old ABI information representation in `CallArg`, but keeps both for now.

Co-authored-by: Tomasz Sowiński <tomeksowi@gmail.com>

Author: jakobbotsch

src/coreclr/jit/abi.cpp

@@ -206,7 +206,7 @@ ABIPassingInformation::ABIPassingInformation(Compiler* comp, unsigned numSegment
 
     if (numSegments > 1)
     {
-        Segments = new (comp, CMK_ABI) ABIPassingSegment[numSegments];
+        m_segments = new (comp, CMK_ABI) ABIPassingSegment[numSegments];
     }
 }
 
@@ -225,10 +225,10 @@ const ABIPassingSegment& ABIPassingInformation::Segment(unsigned index) const
     assert(index < NumSegments);
     if (NumSegments == 1)
     {
-        return SingleSegment;
+        return m_singleSegment;
     }
 
-    return Segments[index];
+    return m_segments[index];
 }
 
 //-----------------------------------------------------------------------------
@@ -265,6 +265,25 @@ bool ABIPassingInformation::HasAnyRegisterSegment() const
     return false;
 }
 
+//-----------------------------------------------------------------------------
+// HasAnyFloatingRegisterSegment:
+//   Check if any part of this value is passed in a floating-point register.
+//
+// Return Value:
+//   True if so.
+//
+bool ABIPassingInformation::HasAnyFloatingRegisterSegment() const
+{
+    for (unsigned i = 0; i < NumSegments; i++)
+    {
+        if (Segment(i).IsPassedInRegister() && genIsValidFloatReg(Segment(i).GetRegister()))
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
 //-----------------------------------------------------------------------------
 // HasAnyStackSegment:
 //   Check if any part of this value is passed on the stack.
@@ -348,8 +367,8 @@ bool ABIPassingInformation::IsSplitAcrossRegistersAndStack() const
 ABIPassingInformation ABIPassingInformation::FromSegment(Compiler* comp, const ABIPassingSegment& segment)
 {
     ABIPassingInformation info;
-    info.NumSegments   = 1;
-    info.SingleSegment = segment;
+    info.NumSegments     = 1;
+    info.m_singleSegment = segment;
     return info;
 }
 
@@ -371,7 +390,7 @@ ABIPassingInformation ABIPassingInformation::FromSegments(Compiler*
 {
     ABIPassingInformation info;
     info.NumSegments = 2;
-    info.Segments    = new (comp, CMK_ABI) ABIPassingSegment[2]{firstSegment, secondSegment};
+    info.m_segments  = new (comp, CMK_ABI) ABIPassingSegment[2]{firstSegment, secondSegment};
     return info;
 }
 

src/coreclr/jit/abi.h

@@ -3,6 +3,9 @@
 
 #pragma once
 
+class ClassLayout;
+enum class WellKnownArg : unsigned;
+
 class ABIPassingSegment
 {
     regNumber m_register    = REG_NA;
@@ -42,8 +45,8 @@ struct ABIPassingInformation
 private:
     union
     {
-        ABIPassingSegment* Segments;
-        ABIPassingSegment  SingleSegment;
+        ABIPassingSegment* m_segments;
+        ABIPassingSegment  m_singleSegment;
     };
 
 public:
@@ -72,6 +75,7 @@ struct ABIPassingInformation
     ABIPassingSegment&       Segment(unsigned index);
 
     bool HasAnyRegisterSegment() const;
+    bool HasAnyFloatingRegisterSegment() const;
     bool HasAnyStackSegment() const;
     bool HasExactlyOneRegisterSegment() const;
     bool HasExactlyOneStackSegment() const;

src/coreclr/jit/gentree.cpp

@@ -1258,87 +1258,6 @@ void CallArgABIInformation::SetHfaType(var_types type, unsigned hfaSlots)
     }
 }
 
-//---------------------------------------------------------------
-// SetByteSize: Set information related to this argument's size and alignment.
-//
-// Arguments:
-//   byteSize      - The size in bytes of the argument.
-//   byteAlignment - The alignment in bytes of the argument.
-//   isStruct      - Whether this arg is a struct.
-//   isFloatHfa    - Whether this is a float HFA.
-//
-// Remarks:
-//   This function will determine how the argument size needs to be rounded. On
-//   most ABIs all arguments are rounded to stack pointer size, but Apple arm64
-//   ABI is an exception as it allows packing some small arguments into the
-//   same stack slot.
-//
-void CallArgABIInformation::SetByteSize(unsigned byteSize, unsigned byteAlignment, bool isStruct, bool isFloatHfa)
-{
-    unsigned roundedByteSize;
-    if (compAppleArm64Abi())
-    {
-        // Only struct types need extension or rounding to pointer size, but HFA<float> does not.
-        if (isStruct && !isFloatHfa)
-        {
-            roundedByteSize = roundUp(byteSize, TARGET_POINTER_SIZE);
-        }
-        else
-        {
-            roundedByteSize = byteSize;
-        }
-    }
-    else
-    {
-        roundedByteSize = roundUp(byteSize, TARGET_POINTER_SIZE);
-    }
-
-#if !defined(TARGET_ARM)
-    // Arm32 could have a struct with 8 byte alignment
-    // which rounded size % 8 is not 0.
-    assert(byteAlignment != 0);
-    assert(roundedByteSize % byteAlignment == 0);
-#endif // TARGET_ARM
-
-    ByteSize      = roundedByteSize;
-    ByteAlignment = byteAlignment;
-}
-
-//---------------------------------------------------------------
-// SetMultiRegsNumw: Set the registers for a multi-reg arg using 'sequential' registers.
-//
-// Remarks:
-//   This assumes that `NumRegs` and the first reg num has already been set and
-//   determines how many sequential registers are necessary to pass the
-//   argument.
-//   Note that on ARM the registers set may skip odd float registers if the arg
-//   is a HFA of doubles, since double and float registers overlap.
-void CallArgABIInformation::SetMultiRegNums()
-{
-#if FEATURE_MULTIREG_ARGS && !defined(UNIX_AMD64_ABI) && !defined(TARGET_LOONGARCH64) && !defined(TARGET_RISCV64)
-    if (NumRegs == 1)
-    {
-        return;
-    }
-
-    regNumber argReg = GetRegNum(0);
-#ifdef TARGET_ARM
-    unsigned int regSize = (GetHfaType() == TYP_DOUBLE) ? 2 : 1;
-#else
-    unsigned int regSize = 1;
-#endif
-
-    if (NumRegs > MAX_ARG_REG_COUNT)
-        NO_WAY("Multireg argument exceeds the maximum length");
-
-    for (unsigned int regIndex = 1; regIndex < NumRegs; regIndex++)
-    {
-        argReg = (regNumber)(argReg + regSize);
-        SetRegNum(regIndex, argReg);
-    }
-#endif // FEATURE_MULTIREG_ARGS && !defined(UNIX_AMD64_ABI) && !defined(TARGET_LOONGARCH64) && !defined(TARGET_RISCV64)
-}
-
 //---------------------------------------------------------------
 // GetStackByteSize: Get the number of stack bytes used to pass this argument.
 //
@@ -1468,7 +1387,7 @@ void CallArg::CheckIsStruct()
 CallArgs::CallArgs()
     : m_head(nullptr)
     , m_lateHead(nullptr)
-    , m_nextStackByteOffset(0)
+    , m_argsStackSize(0)
 #ifdef UNIX_X86_ABI
     , m_stkSizeBytes(0)
     , m_padStkAlign(0)
@@ -9817,7 +9736,7 @@ void CallArgs::InternalCopyFrom(Compiler* comp, CallArgs* other, CopyNodeFunc co
 {
     assert((m_head == nullptr) && (m_lateHead == nullptr));
 
-    m_nextStackByteOffset      = other->m_nextStackByteOffset;
+    m_argsStackSize            = other->m_argsStackSize;
     m_hasThisPointer           = other->m_hasThisPointer;
     m_hasRetBuffer             = other->m_hasRetBuffer;
     m_isVarArgs                = other->m_isVarArgs;
@@ -9845,6 +9764,7 @@ void CallArgs::InternalCopyFrom(Compiler* comp, CallArgs* other, CopyNodeFunc co
         carg->m_isTmp           = arg.m_isTmp;
         carg->m_processed       = arg.m_processed;
         carg->AbiInfo           = arg.AbiInfo;
+        carg->NewAbiInfo        = arg.NewAbiInfo;
         *tail                   = carg;
         tail                    = &carg->m_next;
     }
@@ -13174,6 +13094,8 @@ const char* Compiler::gtGetWellKnownArgNameForArgMsg(WellKnownArg arg)
             return "swift error";
         case WellKnownArg::SwiftSelf:
             return "swift self";
+        case WellKnownArg::X86TailCallSpecialArg:
+            return "tail call";
         default:
             return nullptr;
     }

src/coreclr/jit/gentree.h

@@ -18,6 +18,7 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 #define _GENTREE_H_
 /*****************************************************************************/
 
+#include "abi.h"
 #include "vartype.h"   // For "var_types"
 #include "target.h"    // For "regNumber"
 #include "ssaconfig.h" // For "SsaConfig::RESERVED_SSA_NUM"
@@ -4480,6 +4481,7 @@ enum class WellKnownArg : unsigned
     DispatchIndirectCallTarget,
     SwiftError,
     SwiftSelf,
+    X86TailCallSpecialArg,
 };
 
 #ifdef DEBUG
@@ -4492,12 +4494,10 @@ struct CallArgABIInformation
         : NumRegs(0)
         , ByteOffset(0)
         , ByteSize(0)
-        , ByteAlignment(0)
 #if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
         , StructFloatFieldType()
 #endif
         , ArgType(TYP_UNDEF)
-        , IsBackFilled(false)
         , PassedByRef(false)
 #if FEATURE_ARG_SPLIT
         , m_isSplit(false)
@@ -4523,7 +4523,6 @@ struct CallArgABIInformation
     unsigned NumRegs;
     unsigned ByteOffset;
     unsigned ByteSize;
-    unsigned ByteAlignment;
 #if defined(UNIX_AMD64_ABI)
     // Unix amd64 will split floating point types and integer types in structs
     // between floating point and general purpose registers. Keep track of that
@@ -4541,9 +4540,6 @@ struct CallArgABIInformation
     // that type. Note that if a struct is passed by reference, this will still
     // be the struct type.
     var_types ArgType : 5;
-    // True when the argument fills a register slot skipped due to alignment
-    // requirements of previous arguments.
-    bool IsBackFilled : 1;
     // True iff the argument is passed by reference.
     bool PassedByRef : 1;
 
@@ -4641,18 +4637,11 @@ struct CallArgABIInformation
 #endif // TARGET_LOONGARCH64 || TARGET_RISCV64
     }
 
-    void SetByteSize(unsigned byteSize, unsigned byteAlignment, bool isStruct, bool isFloatHfa);
-
     // Get the number of bytes that this argument is occupying on the stack,
     // including padding up to the target pointer size for platforms
     // where a stack argument can't take less.
     unsigned GetStackByteSize() const;
 
-    // Set the register numbers for a multireg argument.
-    // There's nothing to do on x64/Ux because the structDesc has already been used to set the
-    // register numbers.
-    void SetMultiRegNums();
-
     // Return number of stack slots that this argument is taking.
     // This value is not meaningful on Apple arm64 where multiple arguments can
     // be passed in the same stack slot.
@@ -4755,6 +4744,7 @@ class CallArg
 
 public:
     CallArgABIInformation AbiInfo;
+    ABIPassingInformation NewAbiInfo;
 
     CallArg(const NewCallArg& arg)
         : CallArg()
@@ -4817,7 +4807,7 @@ class CallArgs
     CallArg* m_head;
     CallArg* m_lateHead;
 
-    unsigned m_nextStackByteOffset;
+    unsigned m_argsStackSize;
 #ifdef UNIX_X86_ABI
     // Number of stack bytes pushed before we start pushing these arguments.
     unsigned m_stkSizeBytes;
@@ -4846,7 +4836,6 @@ class CallArgs
     void      AddedWellKnownArg(WellKnownArg arg);
     void      RemovedWellKnownArg(WellKnownArg arg);
     regNumber GetCustomRegister(Compiler* comp, CorInfoCallConvExtension cc, WellKnownArg arg);
-    void      SplitArg(CallArg* arg, unsigned numRegs, unsigned numSlots);
     void      SortArgs(Compiler* comp, GenTreeCall* call, CallArg** sortedArgs);
 
 public:

src/coreclr/jit/lclvars.cpp

@@ -1721,7 +1721,8 @@ void Compiler::lvaInitVarDsc(LclVarDsc*              varDsc,
 template <typename Classifier>
 void Compiler::lvaClassifyParameterABI(Classifier& classifier)
 {
-    lvaParameterPassingInfo = new (this, CMK_LvaTable) ABIPassingInformation[info.compArgsCount];
+    lvaParameterPassingInfo =
+        info.compArgsCount == 0 ? nullptr : new (this, CMK_LvaTable) ABIPassingInformation[info.compArgsCount];
 
     for (unsigned i = 0; i < info.compArgsCount; i++)
     {
@@ -1768,11 +1769,6 @@ void Compiler::lvaClassifyParameterABI(Classifier& classifier)
 //
 void Compiler::lvaClassifyParameterABI()
 {
-    if (info.compArgsCount == 0)
-    {
-        return;
-    }
-
     ClassifierInfo cInfo;
     cInfo.CallConv   = info.compCallConv;
     cInfo.IsVarArgs  = info.compIsVarArgs;

src/coreclr/jit/lower.cpp

@@ -3448,10 +3448,13 @@ void Lowering::LowerCFGCall(GenTreeCall* call)
             call->gtArgs.PushLateBack(targetArg);
 
             // Set up ABI information for this arg.
+            targetArg->NewAbiInfo =
+                ABIPassingInformation::FromSegment(comp, ABIPassingSegment::InRegister(REG_DISPATCH_INDIRECT_CALL_ADDR,
+                                                                                       0, TARGET_POINTER_SIZE));
             targetArg->AbiInfo.ArgType = callTarget->TypeGet();
             targetArg->AbiInfo.SetRegNum(0, REG_DISPATCH_INDIRECT_CALL_ADDR);
-            targetArg->AbiInfo.NumRegs = 1;
-            targetArg->AbiInfo.SetByteSize(TARGET_POINTER_SIZE, TARGET_POINTER_SIZE, false, false);
+            targetArg->AbiInfo.NumRegs  = 1;
+            targetArg->AbiInfo.ByteSize = TARGET_POINTER_SIZE;
 
             // Lower the newly added args now that call is updated
             LowerArg(call, targetArg, true /* late */);

src/coreclr/jit/lsrabuild.cpp

@@ -602,14 +602,7 @@ RefPosition* LinearScan::newRefPosition(Interval*        theInterval,
         regNumber    physicalReg = genRegNumFromMask(mask, theInterval->registerType);
         RefPosition* pos         = newRefPosition(physicalReg, theLocation, RefTypeFixedReg, nullptr, mask);
         assert(theInterval != nullptr);
-#if defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
-        // The LoongArch64's ABI which the float args maybe passed by integer register
-        // when no float register left but free integer register.
-        assert((regType(theInterval->registerType) == FloatRegisterType) ||
-               (allRegs(theInterval->registerType) & mask) != 0);
-#else
         assert((allRegs(theInterval->registerType) & mask) != 0);
-#endif
     }
 
     RefPosition* newRP = newRefPositionRaw(theLocation, theTreeNode, theRefType);