compiler: implement clear builtin for maps

compiler/compiler.go

@@ -1631,6 +1631,10 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 			}, "")
 			call.AddCallSiteAttribute(1, b.ctx.CreateEnumAttribute(llvm.AttributeKindID("align"), uint64(elementAlign)))
 
+			return llvm.Value{}, nil
+		case *types.Map:
+			m := argValues[0]
+			b.createMapClear(m)
 			return llvm.Value{}, nil
 		default:
 			return llvm.Value{}, b.makeError(pos, "unsupported type in clear builtin: "+typ.String())

compiler/map.go

@@ -185,6 +185,11 @@ func (b *builder) createMapDelete(keyType types.Type, m, key llvm.Value, pos tok
 	}
 }
 
+// Clear the given map.
+func (b *builder) createMapClear(m llvm.Value) {
+	b.createRuntimeCall("hashmapClear", []llvm.Value{m}, "")
+}
+
 // 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.

compiler/testdata/go1.21.go

@@ -59,3 +59,7 @@ func clearSlice(s []int) {
 func clearZeroSizedSlice(s []struct{}) {
 	clear(s)
 }
+
+func clearMap(m map[string]int) {
+	clear(m)
+}

compiler/testdata/go1.21.ll

@@ -147,6 +147,15 @@ entry:
   ret void
 }
 
+; Function Attrs: nounwind
+define hidden void @main.clearMap(ptr dereferenceable_or_null(40) %m, ptr %context) unnamed_addr #2 {
+entry:
+  call void @runtime.hashmapClear(ptr %m, ptr undef) #5
+  ret void
+}
+
+declare void @runtime.hashmapClear(ptr dereferenceable_or_null(40), ptr) #1
+
 ; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
 declare i32 @llvm.smin.i32(i32, i32) #4