cmd/link/internal/ld: panic if inlined functions missing FuncInfo

All inlined functions are Go functions, and thus should be capable of
having a FuncInfo. Missing FuncInfo is likely indication of a compiler
bug that dropped the symbol too early, failing to add it to the symbol
list used for writing output. I believe all existing cases have been
fixed; this check will prevent regressions.

The exception is -linkshared mode. There symbols are loaded from the
shared library, and the FuncInfo is not available. This is a bug, as it
can result in incorrect the FuncID in inlinedCall, but it is very
involved to fix.

For #54959.
For #55954.

Change-Id: Ib0dc4f1ea62525b55f68604d6013ff33223fdcdd
Reviewed-on: https://go-review.googlesource.com/c/go/+/429637
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index 2a1e15cddb9d1ce0783123f9d607bed59cb062a6..2f13a24e04f1db612e2ff86fb79d2b4e326d2fce 100644 (file)
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -171,7 +171,18 @@ func genInlTreeSym(ctxt *Link, cu *sym.CompilationUnit, fi loader.FuncInfo, arch
                var funcID objabi.FuncID
                if inlFunc.Valid() {
                        funcID = inlFunc.FuncID()
+               } else if !ctxt.linkShared {
+                       // Inlined functions are always Go functions, and thus
+                       // must have FuncInfo.
+                       //
+                       // Unfortunately, with -linkshared, the inlined
+                       // function may be external symbols (from another
+                       // shared library), and we don't load FuncInfo from the
+                       // shared library. We will report potentially incorrect
+                       // FuncID in this case. See https://go.dev/issue/55954.
+                       panic(fmt.Sprintf("inlined function %s missing func info", ldr.SymName(call.Func)))
                }
+
                // Construct runtime.inlinedCall value.
                const size = 12
                inlTreeSym.SetUint8(arch, int64(i*size+0), uint8(funcID))