Issue with PC updates.

[Sid Manning]

Hi Taylor,

I ran into an issue when a packet, not executed out of ram 
(get_page_addr_code_hostp returns -1, see translate-all.c) contains a fault.
This packet is an example:
{
    p0 = cmp.eq(r6,#0x6)
    if (p0.new) jump:t pass
    memw(##0xf2000000) = r6
}

The above packet should always jump to "pass" since r6 is set to #0x6, but if 
the store faults, the jump is discarded.  This happens because 
do_raise_exception's call to cpu_loop_exit_restore is not able to find a TB to 
restore the PC to.  When an instruction is not associated with a physical RAM 
page translate-all will create a "one-shot" TB so when cpu_restore_state looks 
for the TB by calling tcg_tb_loopup none is found.  That keeps the PC from 
being restored.

The change attached restores some of the code from commit 
613653e500c0d482784f09aaa71f1297565b6815 / Hexagon (target/hexagon) Remove 
next_PC from runtime state.

There are two attachments, the qemu update also includes an update to 
translate-all.c that forces this problem to occur.  The second is the testcase 
which is built using vanilla llvm toolchain configured for hexagon.

Thanks,

pc-testcase.tar.gz
Description: pc-testcase.tar.gz

0001-Incorrect-PC-update-for-many-miss-packets.patch
Description: 0001-Incorrect-PC-update-for-many-miss-packets.patch