On 7/29/24 8:52 AM, Raphael Zinsly wrote:
On Mon, Jul 29, 2024 at 11:20 AM Jeff Law <jeffreya...@gmail.com> wrote:
On 7/29/24 6:18 AM, Raphael Zinsly wrote:
On Fri, Jul 26, 2024 at 6:48 PM Jeff Law <jeffreya...@gmail.com> wrote:
On 7/24/24 12:00 PM, Raphael Moreira Zinsly wrote:
Adds basic support to vector stack-clash protection using a loop to do
the probing and stack adjustments.
gcc/ChangeLog:
* config/riscv/riscv.cc
(riscv_allocate_and_probe_stack_loop): New function.
(riscv_v_adjust_scalable_frame): Add stack-clash protection
support.
(riscv_allocate_and_probe_stack_space): Move the probe loop
implementation to riscv_allocate_and_probe_stack_loop.
* config/riscv/riscv.h: Define RISCV_STACK_CLASH_VECTOR_CFA_REGNUM.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/stack-check-cfa-3.c: New test.
* gcc.target/riscv/stack-check-prologue-16.c: New test.
* gcc.target/riscv/struct_vect_24.c: New test.
So my only worry here is using another scratch register in the prologue
code instead of using one of the preexisting prologue scratch registers.
Is there a reasonable way to use PROLOGUE_TEMP or PROLOGUE_TEMP2 here?
These are the preexisting prologue scratch registers: PROLOGUE_TEMP is
t0 and PROLOGUE_TEMP2 is t1.
Otherwise this looks good as well. So let's get closure on that
question and we can move forward after that.
Right. And so my question is can we use PROLOGUE_TEMP or PROLOGUE_TEMP2
rather than defining another temporary for the prologue?
We are only using these two and we do not need to use another temporary.
Do you mean stop using riscv_force_temporary?
If so, yes, we can change it to riscv_emit_move.
You define:
+#define RISCV_STACK_CLASH_VECTOR_CFA_REGNUM (GP_TEMP_FIRST + 4)
Where:
#define GP_REG_FIRST 0
#define GP_TEMP_FIRST (GP_REG_FIRST + 5)
So RISCV_STACK_CLASH_VECTOR_CFA_REGNUM defined as "9" which I think is
"s1". That can't be what we want :-)
What I don't understand is why we don't use RISCV_PROLOGUE_TEMP_REGNUM
or RISCV_PROLOGUE_TEMP2_REGNUM which are defined as t0 and t1 respectively.
We'd have to audit the prologue/epilogue code to ensure we can safely
use one of those two as a scratch in the context we care about.
jeff
