RE: [PATCH] Hexagon: add PC alignment check and exception

[ltaylorsimpson]

> -----Original Message-----
> From: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
> Sent: Friday, April 26, 2024 1:16 PM
> To: qemu-devel@nongnu.org
> Cc: bcain@quicinc.com; sidneym@quicinc.com; ale@rev.ng; anjo@rev.ng;
> ltaylorsimpson@gmail.com
> Subject: [PATCH] Hexagon: add PC alignment check and exception
> 
> The Hexagon Programmer's Reference Manual says that the exception 0x1e
> should be raised upon an unaligned program counter. Let's implement that
> and also add tests for both the most common case as well as packets with
> multiple change-of-flow instructions.
> 
> Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
> ---


> --- a/target/hexagon/genptr.c
> +++ b/target/hexagon/genptr.c
> @@ -473,6 +473,7 @@ static void gen_write_new_pc_addr(DisasContext

You haven't added the check to gen_write_new_pc_pcrel.  It's not needed
there because the encoding guarantees the target is always aligned - right?
However, there is a call to gen_write_new_pc_addr inside that function.  In
this case, we'll add a check that isn't necessary.  Consider adding a
parameter to indicate if the check can be avoided.


> a/tests/tcg/hexagon/Makefile.target b/tests/tcg/hexagon/Makefile.target
> index f839b2c0d5..02d7fff34c 100644
> --- a/tests/tcg/hexagon/Makefile.target
> +++ b/tests/tcg/hexagon/Makefile.target
> @@ -51,6 +51,19 @@ HEX_TESTS += scatter_gather  HEX_TESTS += hvx_misc
> HEX_TESTS += hvx_histogram  HEX_TESTS += invalid-slots
> +HEX_TESTS += unaligned_pc
> +HEX_TESTS += unaligned_pc_multi_cof
> +
> +run-unaligned_pc: unaligned_pc
> +run-unaligned_pc_multi_cof: unaligned_pc_multi_cof run-unaligned_pc
> +run-unaligned_pc_multi_cof:
> +     $(call run-test, $<, $(QEMU) $< 2> $<.stderr,"$< on
> $(TARGET_NAME)"); \
> +     if [ $$? -ne 1 ] ; then \
> +             return 1; \
> +     fi
> +     $(call quiet-command, \
> +             grep -q "exception 0x1e" $<.stderr, \
> +             "GREP", "exception 0x1e");

We should also test endloop instructions.

Thanks,
Taylor