Go patch committed: copy signal code from Go 1.7 runtime

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

This patch to the Go frontend and libgo copies the signal code from
the Go 1.7 runtime.

This adds a little shell script to auto-generate runtime.sigtable from
the known signal names.

This forces the main package to always import the runtime package.
Otherwise some runtime package global variables may never be
initialized.

This sets the syscallsp and syscallpc fields of g when entering a
syscall, so that the runtime package knows when a g is executing a
syscall.

This fixes runtime.funcPC to avoid dead store elimination of the
interface value when the function is inlined.

The signal code in C now has some target-specific code to return the
PC where the signal occurred and to dump the registers on a hard
crash.  This is what the gc toolchain does as well.  I wrote versions
of that code for x86 GNU/Linux.  Other targets will fall back
reasonably and display less information.

Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.
Bootstrapped and ran relevant tests on sparc-sun-solaris.  Committed
to mainline.

Ian

Attachment: patch.txt
Description: Text document