libgo patch committed: Change some stack fields to uintptr

[Ian Lance Taylor <iant at golang dot org>]

Because of how gccgo implements cgo calls, the code in dropm may not
have any write barriers.  As a step toward implementing that, change
the gcstack, gcnextsegment, and gcnextsp fields of the g struct to
uintptr, so that assignments to them do not require write barriers.
The gcinitialsp field remains unsafe.Pointer, as on 32-bit systems
that do not support split stack it points to a heap allocated space
used for the goroutine stack.

The test for this is runtime tests like TestCgoCallbackGC, which are
not run today but will be run with a future gotools patch.

Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian

Attachment: patch.txt
Description: Text document