t.Skipf("skipping on %s/%s: runtime does not permit SI_USER SIGSEGV", GOOS, GOARCH)
	}
	globalSkip(t)
	checkSignalForwardingTest(t)
	buildSignalForwardingTest(t)

	// We want to send the process a signal and see if it dies.
	// Normally the signal goes to the C thread, the Go signal
	// handler picks it up, sees that it is running in a C thread,
	// and the program dies. Unfortunately, occasionally the

	// i.e. struct fields and array elements, even with non-constant
	// indices: x is non-nil iff x.a.b[i].c is.

	type walkState int
	const (
		Work     walkState = iota // process nil checks and traverse to dominees
		ClearPtr                  // forget the fact that ptr is nil
	)

	type bp struct {
		block *Block // block, or nil in ClearPtr state

	// An object's type (and thus the object) may be in one of
	// three states which are expressed by colors:
	//
	// - an object whose type is not yet known is painted white (initial color)
	// - an object whose type is in the process of being inferred is painted grey
	// - an object whose type is fully inferred is painted black
	//
	// During type inference, an object's color changes from white to grey

// The compiler is compiled with itself. If an output were represented by its
// own action ID (instead of content ID) when computing the action ID of
// the next step in the build process, then the compiler could never have its
// own input action ID as its output action ID (short of a miraculous hash collision).
// Instead we use the content IDs to compute the next action ID, and because

		if err != nil {
			if err != io.EOF {
				return err
			}
			if input == "" {
				return nil
			}
		}

		for _, input := range shortcuts.expand(input) {
			// Process assignments of the form variable=value
			if s := strings.SplitN(input, "=", 2); len(s) > 0 {
				name := strings.TrimSpace(s[0])
				var value string
				if len(s) == 2 {
					value = s[1]

			ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_X86_64_GLOB_DAT))

			su.SetRelocSym(rIdx, syms.GOT)
			su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
			return true
		}

		// Process dynamic relocations for the data sections.
		if target.IsPIE() && target.IsInternal() {
			// When internally linking, generate dynamic relocations
			// for all typical R_ADDR relocations. The exception

	}
	word, cond = p.lex.Text(), ""
	operands = scratch[:0]
	// Zero or more comma-separated operands, one per loop.
	nesting := 0
	colon := -1
	for tok != '\n' && tok != ';' {
		// Process one operand.
		var items []lex.Token
		if cap(operands) > len(operands) {
			// Reuse scratch items slice.
			items = operands[:cap(operands)][len(operands)][:0]
		} else {
			items = make([]lex.Token, 0, 3)

			// The prefix was not a valid module path, and there was no replacement.
			// Prefixes like this may appear in candidateModules, since we handle
			// replaced modules that weren't required in the repo lookup process
			// (see lookupRepo).
			//
			// A shorter prefix may be a valid module path and may contain a valid
			// import path, so this is a low-priority error.
			if invalidPath == nil {
				invalidPath = rErr
			}

	// exist on disk for until Close is called (at the end of the process).
	Put(ActionID, io.ReadSeeker) (_ OutputID, size int64, _ error)

	// Close is called at the end of the go process. Implementations can do
	// cache cleanup work at this phase, or wait for and report any errors from
	// background cleanup work started earlier. Any cache trimming should in one
	// process should not violate cause the invariants of this interface to be

fail for reasons that are irrelevant when using external linking mode.

The final program will be a dynamic executable, so that cmd/link can avoid
needing to process arbitrary .o files. It only needs to process the .o
files generated from C files that cgo writes, and those are much more
limited in the ELF or other features that they use.

In essence, the _cgo_import.o file includes the extra linking