cmd/compile: fix unified IR panic when expanding nested inline function

When reading body of inlining function, which has another inlined
function in the body, the reader still add this inlined function to
todoBodies, which it shouldn't because the inlined function was read
already.

To fix this, introduce new flag to signal that we are done construting
all functions in todoBodies, thus the addBody shouldn't add anything
to todoBodies then.

Updates #48094

Change-Id: I45105dd518f0a7b69c6dcbaf23b957623f271203
Reviewed-on: https://go-review.googlesource.com/c/go/+/347529
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index 57e8476099..48f4368113 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -927,6 +927,11 @@ var bodyReader = map[*ir.Func]pkgReaderIndex{}
 // constructed.
 var todoBodies []*ir.Func
 
+// todoBodiesDone signals that we constructed all function in todoBodies.
+// This is necessary to prevent reader.addBody adds thing to todoBodies
+// when nested inlining happens.
+var todoBodiesDone = false
+
 func (r *reader) addBody(fn *ir.Func) {
 	pri := pkgReaderIndex{r.p, r.reloc(relocBody), r.dict}
 	bodyReader[fn] = pri
@@ -937,7 +942,7 @@ func (r *reader) addBody(fn *ir.Func) {
 		return
 	}
 
-	if r.curfn == nil {
+	if r.curfn == nil && !todoBodiesDone {
 		todoBodies = append(todoBodies, fn)
 		return
 	}