Direct block chaining is documented here
https://qemu.readthedocs.io/en/latest/devel/tcg.html#direct-block-chaining
Hexagon inner loops end with the endloop0 instruction
To go back to the beginning of the loop, this instructions writes to PC
from register SA0 (start address 0). To use direct block chaining, we
have to assign PC with a constant value. So, we specialize the code
generation when the start of the translation block is equal to SA0.
When this is the case, we defer the compare/branch from endloop0 to
gen_end_tb. When this is done, we can assign the start address of the TB
to PC.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221108162906.3166-12-tsimpson@quicinc.com>
Direct block chaining is documented here
https://qemu.readthedocs.io/en/latest/devel/tcg.html#direct-block-chaining
Recall that Hexagon allows packets with multiple jumps where only the
first one with a true predicate will actually jump. We can use
tcg_gen_goto_tb/tcg_gen_exit_tb when the packet contains a single
PC-relative branch or jump. If not, we use tcg_gen_lookup_and_goto_ptr.
We add the following to DisasContext in order to delay the branching
until the end of packet commit (in gen_end_tb)
branch_cond
The TCGCond condition under which the branch is taken
When branch_cond == TCG_COND_NEVER, there isn't a single
direct branch in this packet.
When branch_cond != TCG_COND_ALWAYS, the value is in
hex_branch_taken
branch_dest
The destination of the branch
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221108162906.3166-11-tsimpson@quicinc.com>
The imported files don't properly mark all CONDEXEC instructions, so
we add some logic to hex_common.py to add the attribute.
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221108162906.3166-7-tsimpson@quicinc.com>
Here are example instructions with a predicated .tmp/.cur assignment
if (p1) v12.tmp = vmem(r7 + #0)
if (p0) v12.cur = vmem(r9 + #0)
The .tmp/.cur indicates that references to v12 in the same packet
take the result of the load. However, when the predicate is false,
the value at the start of the packet should be used. After the packet
commits, the .tmp value is dropped, but the .cur value is maintained.
To fix this bug, we preload the original value from the HVX register
into the temporary used for the result.
Test cases added to tests/tcg/hexagon/hvx_misc.c
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Co-authored-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221108162906.3166-3-tsimpson@quicinc.com>
This enables us to reduce the number of parameters to many functions
In particular, the generated functions previously took all 3 as arguments
Not only does this simplify the code, it improves the translation time
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <20221108162906.3166-2-tsimpson@quicinc.com>
Many files use "qemu/log.h" declarations but neglect to include
it (they inherit it via "exec/exec-all.h"). "exec/exec-all.h" is
a core component and shouldn't be used that way. Move the
"qemu/log.h" inclusion locally to each unit requiring it.
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220207082756.82600-10-f4bug@amsat.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Change #if HEX_DEBUG to if (HEX_DEBUG) so the debug code doesn't bit rot
Suggested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1617930474-31979-17-git-send-email-tsimpson@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1617930474-31979-8-git-send-email-tsimpson@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Multiple writes to the same preg are and'ed together. Rather than
generating a runtime check, we can determine at TCG generation time
if the predicate has previously been written in the packet.
Test added to tests/tcg/hexagon/misc.c
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1617930474-31979-7-git-send-email-tsimpson@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
When exiting a TB, generate all the code before returning from
hexagon_tr_translate_packet so that nothing needs to be done in
hexagon_tr_tb_stop.
Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1617930474-31979-6-git-send-email-tsimpson@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Read the instruction memory
Create a packet data structure
Generate TCG code for the start of the packet
Invoke the generate function for each instruction
Generate TCG code for the end of the packet
Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Message-Id: <1612763186-18161-30-git-send-email-tsimpson@quicinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
