transform: allow updating tests with -update flag

This should make it much easier to update existing tests.

transform/testdata/allocs.out.ll

@@ -54,13 +54,15 @@ define void @testNonEscapingLoop() {
 entry:
   %stackalloc.alloca = alloca [1 x i32]
   br label %loop
-loop:
+
+loop:                                             ; preds = %loop, %entry
   store [1 x i32] zeroinitializer, [1 x i32]* %stackalloc.alloca
   %stackalloc = bitcast [1 x i32]* %stackalloc.alloca to i32*
   %0 = call i32* @noescapeIntPtr(i32* %stackalloc)
   %1 = icmp eq i32* null, %0
   br i1 %1, label %loop, label %end
-end:
+
+end:                                              ; preds = %loop
   ret void
 }
 

transform/testdata/coroutines.out.ll

@@ -5,11 +5,13 @@ target triple = "armv7m-none-eabi"
 %"internal/task.state" = type { i8* }
 
 declare void @"internal/task.start"(i32, i8*, i8*, i8*)
+
 declare void @"internal/task.Pause"(i8*, i8*)
 
 declare void @runtime.scheduler(i8*, i8*)
 
 declare i8* @runtime.alloc(i32, i8*, i8*)
+
 declare void @runtime.free(i8*, i8*, i8*)
 
 declare %"internal/task.Task"* @"internal/task.Current"(i8*, i8*)
@@ -17,9 +19,11 @@ declare %"internal/task.Task"* @"internal/task.Current"(i8*, i8*)
 declare i8* @"(*internal/task.Task).setState"(%"internal/task.Task"*, i8*, i8*, i8*)
 
 declare void @"(*internal/task.Task).setReturnPtr"(%"internal/task.Task"*, i8*, i8*, i8*)
+
 declare i8* @"(*internal/task.Task).getReturnPtr"(%"internal/task.Task"*, i8*, i8*)
 
 declare void @"(*internal/task.Task).returnTo"(%"internal/task.Task"*, i8*, i8*, i8*)
+
 declare void @"(*internal/task.Task).returnCurrent"(%"internal/task.Task"*, i8*, i8*)
 
 declare %"internal/task.Task"* @"internal/task.createTask"(i8*, i8*)
@@ -27,6 +31,7 @@ declare %"internal/task.Task"* @"internal/task.createTask"(i8*, i8*)
 declare void @callMain(i8*, i8*)
 
 declare void @enqueueTimer(%"internal/task.Task"*, i64, i8*, i8*)
+
 define void @sleep(i64, i8*, i8* %parentHandle) {
 entry:
   %task.current = bitcast i8* %parentHandle to %"internal/task.Task"*
@@ -159,15 +164,31 @@ entry:
   ret void
 }
 
+; Function Attrs: argmemonly nounwind readonly
 declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*) #0
+
+; Function Attrs: nounwind readnone
 declare i32 @llvm.coro.size.i32() #1
+
+; Function Attrs: nounwind
 declare i8* @llvm.coro.begin(token, i8* writeonly) #2
+
+; Function Attrs: nounwind
 declare i8 @llvm.coro.suspend(token, i1) #2
+
+; Function Attrs: nounwind
 declare i1 @llvm.coro.end(i8*, i1) #2
+
+; Function Attrs: argmemonly nounwind readonly
 declare i8* @llvm.coro.free(token, i8* nocapture readonly) #0
+
+; Function Attrs: nounwind
 declare token @llvm.coro.save(i8*) #2
 
+; Function Attrs: argmemonly nounwind
 declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #3
+
+; Function Attrs: argmemonly nounwind
 declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #3
 
 attributes #0 = { argmemonly nounwind readonly }

transform/testdata/func-lowering.out.ll

@@ -29,9 +29,6 @@ declare void @func1Uint8(i8, i8*, i8*)
 
 declare void @func2Uint8(i8, i8*, i8*)
 
-; Call a function of which only one function with this signature is used as a
-; function value. This means that lowering it to IR is trivial: simply check
-; whether the func value is nil, and if not, call that one function directly.
 define void @runFunc1(i8*, i32, i8, i8* %context, i8* %parentHandle) {
 entry:
   %3 = icmp eq i32 %1, 0
@@ -39,53 +36,49 @@ entry:
   %5 = icmp eq void (i8, i8*, i8*)* %4, null
   br i1 %5, label %fpcall.nil, label %fpcall.next
 
-fpcall.nil:
+fpcall.nil:                                       ; preds = %entry
   call void @runtime.nilPanic(i8* undef, i8* null)
   unreachable
 
-fpcall.next:
+fpcall.next:                                      ; preds = %entry
   call void %4(i8 %2, i8* %0, i8* undef)
   ret void
 }
 
-; There are two functions with this signature used in a func value. That means
-; that we'll have to check at runtime which of the two it is (or whether the
-; func value is nil). This call will thus be lowered to a switch statement.
 define void @runFunc2(i8*, i32, i8, i8* %context, i8* %parentHandle) {
 entry:
   br i1 false, label %fpcall.nil, label %fpcall.next
 
-fpcall.nil:
+fpcall.nil:                                       ; preds = %entry
   call void @runtime.nilPanic(i8* undef, i8* null)
   unreachable
 
-fpcall.next:
+fpcall.next:                                      ; preds = %entry
   switch i32 %1, label %func.default [
     i32 0, label %func.nil
     i32 1, label %func.call1
     i32 2, label %func.call2
   ]
 
-func.nil:
+func.nil:                                         ; preds = %fpcall.next
   call void @runtime.nilPanic(i8* undef, i8* null)
   unreachable
 
-func.call1:
+func.call1:                                       ; preds = %fpcall.next
   call void @func1Uint8(i8 %2, i8* %0, i8* undef)
   br label %func.next
 
-func.call2:
+func.call2:                                       ; preds = %fpcall.next
   call void @func2Uint8(i8 %2, i8* %0, i8* undef)
   br label %func.next
 
-func.next:
+func.next:                                        ; preds = %func.call2, %func.call1
   ret void
 
-func.default:
+func.default:                                     ; preds = %fpcall.next
   unreachable
 }
 
-; Special case for runtime.makeGoroutine.
 define void @sleepFuncValue(i8*, i32, i8* nocapture readnone %context, i8* nocapture readnone %parentHandle) {
 entry:
   switch i32 %1, label %func.default [
@@ -94,21 +87,21 @@ entry:
     i32 2, label %func.call2
   ]
 
-func.nil:
+func.nil:                                         ; preds = %entry
   call void @runtime.nilPanic(i8* undef, i8* null)
   unreachable
 
-func.call1:
+func.call1:                                       ; preds = %entry
   call void @"internal/task.start"(i32 ptrtoint (void (i32, i8*, i8*)* @"main$1" to i32), i8* null, i8* undef, i8* null)
   br label %func.next
 
-func.call2:
+func.call2:                                       ; preds = %entry
   call void @"internal/task.start"(i32 ptrtoint (void (i32, i8*, i8*)* @"main$2" to i32), i8* null, i8* undef, i8* null)
   br label %func.next
 
-func.next:
+func.next:                                        ; preds = %func.call2, %func.call1
   ret void
 
-func.default:
+func.default:                                     ; preds = %entry
   unreachable
 }

transform/testdata/interface.out.ll

@@ -36,32 +36,32 @@ define void @printInterface(i32 %typecode, i8* %value) {
   %typeassert.ok1 = call i1 @"Unmatched$typeassert"(i32 %typecode)
   br i1 %typeassert.ok1, label %typeswitch.Unmatched, label %typeswitch.notUnmatched
 
-typeswitch.Unmatched:
+typeswitch.Unmatched:                             ; preds = %0
   %unmatched = ptrtoint i8* %value to i32
   call void @runtime.printptr(i32 %unmatched)
   call void @runtime.printnl()
   ret void
 
-typeswitch.notUnmatched:
+typeswitch.notUnmatched:                          ; preds = %0
   %typeassert.ok = call i1 @"Doubler$typeassert"(i32 %typecode)
   br i1 %typeassert.ok, label %typeswitch.Doubler, label %typeswitch.notDoubler
 
-typeswitch.Doubler:
+typeswitch.Doubler:                               ; preds = %typeswitch.notUnmatched
   %doubler.result = call i32 @"(Number).Double$invoke"(i8* %value, i8* null)
   call void @runtime.printint32(i32 %doubler.result)
   ret void
 
-typeswitch.notDoubler:
+typeswitch.notDoubler:                            ; preds = %typeswitch.notUnmatched
   %typeassert.ok2 = icmp eq i32 16, %typecode
   br i1 %typeassert.ok2, label %typeswitch.byte, label %typeswitch.notByte
 
-typeswitch.byte:
+typeswitch.byte:                                  ; preds = %typeswitch.notDoubler
   %byte = ptrtoint i8* %value to i8
   call void @runtime.printuint8(i8 %byte)
   call void @runtime.printnl()
   ret void
 
-typeswitch.notByte:
+typeswitch.notByte:                               ; preds = %typeswitch.notDoubler
   ret void
 }
 
@@ -82,10 +82,10 @@ entry:
     i32 68, label %then
   ]
 
-then:
+then:                                             ; preds = %entry
   ret i1 true
 
-else:
+else:                                             ; preds = %entry
   ret i1 false
 }
 
@@ -94,9 +94,9 @@ entry:
   switch i32 %actualType, label %else [
   ]
 
-then:
+then:                                             ; No predecessors!
   ret i1 true
 
-else:
+else:                                             ; preds = %entry
   ret i1 false
 }

transform/transform_test.go

@@ -3,6 +3,7 @@ package transform
 // This file defines some helper functions for testing transforms.
 
 import (
+	"flag"
 	"io/ioutil"
 	"os"
 	"strings"
@@ -11,6 +12,8 @@ import (
 	"tinygo.org/x/go-llvm"
 )
 
+var update = flag.Bool("update", false, "update transform package tests")
+
 // testTransform runs a transformation pass on an input file (pathPrefix+".ll")
 // and checks whether it matches the expected output (pathPrefix+".out.ll"). The
 // output is compared with a fuzzy match that ignores some irrelevant lines such
@@ -31,6 +34,16 @@ func testTransform(t *testing.T, pathPrefix string, transform func(mod llvm.Modu
 	// Perform the transform.
 	transform(mod)
 
+	// Get the output from the test and filter some irrelevant lines.
+	actual := mod.String()
+	actual = actual[strings.Index(actual, "\ntarget datalayout = ")+1:]
+
+	if *update {
+		err := ioutil.WriteFile(pathPrefix+".out.ll", []byte(actual), 0666)
+		if err != nil {
+			t.Error("failed to write out new output:", err)
+		}
+	} else {
 		// Read the expected output IR.
 		out, err := ioutil.ReadFile(pathPrefix + ".out.ll")
 		if err != nil {
@@ -39,12 +52,12 @@ func testTransform(t *testing.T, pathPrefix string, transform func(mod llvm.Modu
 
 		// See whether the transform output matches with the expected output IR.
 		expected := string(out)
-	actual := mod.String()
 		if !fuzzyEqualIR(expected, actual) {
 			t.Logf("output does not match expected output:\n%s", actual)
 			t.Fail()
 		}
 	}
+}
 
 // fuzzyEqualIR returns true if the two LLVM IR strings passed in are roughly
 // equal. That means, only relevant lines are compared (excluding comments