Swift SIL: fix var ApplySite.arguments

In case of type-dependent operands, not all operands are part of the arguments

Author: eeckstein

SwiftCompilerSources/Sources/SIL/ApplySite.swift

@@ -30,7 +30,10 @@ extension ApplySite {
   public var callee: Value { operands[ApplyOperands.calleeOperandIndex].value }
 
   public var arguments: LazyMapSequence<OperandArray, Value> {
-    operands[1..<operands.count].lazy.map { $0.value }
+    let numArgs = ApplySite_getNumArguments(bridged)
+    let offset = ApplyOperands.firstArgumentIndex
+    let argOps = operands[offset..<(numArgs + offset)]
+    return argOps.lazy.map { $0.value }
   }
 
   public var substitutionMap: SubstitutionMap {

SwiftCompilerSources/Sources/SIL/Operand.swift

@@ -70,6 +70,9 @@ public struct OperandArray : RandomAccessCollection, CustomReflectable {
     return Mirror(self, children: c)
   }
 
+  /// Returns a sub-array defined by `bounds`.
+  ///
+  /// Note: this does not return a Slice. The first index of the returnd array is always 0.
   public subscript(bounds: Range<Int>) -> OperandArray {
     precondition(bounds.lowerBound >= 0)
     precondition(bounds.upperBound <= endIndex)

include/swift/SIL/SILBridging.h

@@ -328,6 +328,7 @@ SwiftInt CondBranchInst_getNumTrueArgs(BridgedInstruction cbr);
 BridgedSubstitutionMap ApplySite_getSubstitutionMap(BridgedInstruction inst);
 BridgedArgumentConvention
 ApplySite_getArgumentConvention(BridgedInstruction inst, SwiftInt calleeArgIdx);
+SwiftInt ApplySite_getNumArguments(BridgedInstruction inst);
 
 BridgedInstruction SILBuilder_createBuiltinBinaryFunction(
           BridgedBuilder builder, BridgedStringRef name,

lib/SIL/Utils/SILBridging.cpp

@@ -778,6 +778,11 @@ ApplySite_getArgumentConvention(BridgedInstruction inst, SwiftInt calleeArgIdx)
   }
 }
 
+SwiftInt ApplySite_getNumArguments(BridgedInstruction inst) {
+  auto as = ApplySite(castToInst(inst));
+  return as.getNumArguments();
+}
+
 //===----------------------------------------------------------------------===//
 //                                SILBuilder
 //===----------------------------------------------------------------------===//