compiler: move *ssa.Next lowering for maps to compiler/map.go

This moves it to the most logical place, as a preparation to fixing a
bug in the next commit.

compiler/compiler.go

@@ -1792,20 +1792,7 @@ func (b *builder) createExpr(expr ssa.Value) (llvm.Value, error) {
 		if expr.IsString {
 			return b.createRuntimeCall("stringNext", []llvm.Value{llvmRangeVal, it}, "range.next"), nil
 		} else { // map
-			llvmKeyType := b.getLLVMType(rangeVal.Type().Underlying().(*types.Map).Key())
-			llvmValueType := b.getLLVMType(rangeVal.Type().Underlying().(*types.Map).Elem())
-
-			mapKeyAlloca, mapKeyPtr, mapKeySize := b.createTemporaryAlloca(llvmKeyType, "range.key")
-			mapValueAlloca, mapValuePtr, mapValueSize := b.createTemporaryAlloca(llvmValueType, "range.value")
-			ok := b.createRuntimeCall("hashmapNext", []llvm.Value{llvmRangeVal, it, mapKeyPtr, mapValuePtr}, "range.next")
-
-			tuple := llvm.Undef(b.ctx.StructType([]llvm.Type{b.ctx.Int1Type(), llvmKeyType, llvmValueType}, false))
-			tuple = b.CreateInsertValue(tuple, ok, 0, "")
-			tuple = b.CreateInsertValue(tuple, b.CreateLoad(mapKeyAlloca, ""), 1, "")
-			tuple = b.CreateInsertValue(tuple, b.CreateLoad(mapValueAlloca, ""), 2, "")
-			b.emitLifetimeEnd(mapKeyPtr, mapKeySize)
-			b.emitLifetimeEnd(mapValuePtr, mapValueSize)
-			return tuple, nil
+			return b.createMapIteratorNext(rangeVal, llvmRangeVal, it), nil
 		}
 	case *ssa.Phi:
 		phi := b.CreatePHI(b.getLLVMType(expr.Type()), "")

compiler/map.go

@@ -167,6 +167,26 @@ func (b *builder) createMapDelete(keyType types.Type, m, key llvm.Value, pos tok
 	}
 }
 
+// createMapIteratorNext lowers the *ssa.Next instruction for iterating over a
+// map. It returns a tuple of {bool, key, value} with the result of the
+// iteration.
+func (b *builder) createMapIteratorNext(rangeVal ssa.Value, llvmRangeVal, it llvm.Value) llvm.Value {
+	llvmKeyType := b.getLLVMType(rangeVal.Type().Underlying().(*types.Map).Key())
+	llvmValueType := b.getLLVMType(rangeVal.Type().Underlying().(*types.Map).Elem())
+
+	mapKeyAlloca, mapKeyPtr, mapKeySize := b.createTemporaryAlloca(llvmKeyType, "range.key")
+	mapValueAlloca, mapValuePtr, mapValueSize := b.createTemporaryAlloca(llvmValueType, "range.value")
+	ok := b.createRuntimeCall("hashmapNext", []llvm.Value{llvmRangeVal, it, mapKeyPtr, mapValuePtr}, "range.next")
+
+	tuple := llvm.Undef(b.ctx.StructType([]llvm.Type{b.ctx.Int1Type(), llvmKeyType, llvmValueType}, false))
+	tuple = b.CreateInsertValue(tuple, ok, 0, "")
+	tuple = b.CreateInsertValue(tuple, b.CreateLoad(mapKeyAlloca, ""), 1, "")
+	tuple = b.CreateInsertValue(tuple, b.CreateLoad(mapValueAlloca, ""), 2, "")
+	b.emitLifetimeEnd(mapKeyPtr, mapKeySize)
+	b.emitLifetimeEnd(mapValuePtr, mapValueSize)
+	return tuple
+}
+
 // Returns true if this key type does not contain strings, interfaces etc., so
 // can be compared with runtime.memequal.
 func hashmapIsBinaryKey(keyType types.Type) bool {