Looks good in general, but like you say, it's GCC 12 material.
Alex Coplan <alex.cop...@arm.com> writes:
> diff --git a/gcc/config/aarch64/aarch64-bti-insert.c
> b/gcc/config/aarch64/aarch64-bti-insert.c
> index 936649769c7..943fa3c1097 100644
> --- a/gcc/config/aarch64/aarch64-bti-insert.c
> +++ b/gcc/config/aarch64/aarch64-bti-insert.c
> @@ -120,6 +120,13 @@ aarch64_pac_insn_p (rtx x)
> return false;
> }
>
> +static bool
> +aarch64_bti_j_insn_p (rtx_insn *insn)
> +{
> + rtx pat = PATTERN (insn);
> + return GET_CODE (pat) == UNSPEC_VOLATILE && XINT (pat, 1) == UNSPECV_BTI_J;
> +}
> +
Nit, but even a simple function like this should have a comment. :-)
> /* Insert the BTI instruction. */
> /* This is implemented as a late RTL pass that runs before branch
> shortening and does the following. */
> @@ -165,6 +172,9 @@ rest_of_insert_bti (void)
> for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
> {
> label = as_a <rtx_insn *> (XEXP (RTVEC_ELT (vec, j), 0));
> + if (aarch64_bti_j_insn_p (next_nonnote_insn (label)))
> + continue;
> +
This should be next_nonnote_nondebug_insn (quite the mouthful),
otherwise debug instructions could affect the choice.
The thing returned by next_nonnote_nondebug_insn isn't in general
guaranteed to be an insn (unlike next_real_nondebug_insn). It might
also be null in very odd cases. I think we should therefore check
for null and INSN_P before checking PATTERN.
Thanks,
Richard
> bti_insn = gen_bti_j ();
> emit_insn_after (bti_insn, label);
> }
> diff --git a/gcc/testsuite/gcc.target/aarch64/pr99988.c
> b/gcc/testsuite/gcc.target/aarch64/pr99988.c
> new file mode 100644
> index 00000000000..2d87f41a717
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/pr99988.c
> @@ -0,0 +1,66 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mbranch-protection=standard" } */
> +/* { dg-final { scan-assembler-times {bti j} 13 } } */
> +int a;
> +int c();
> +int d();
> +int e();
> +int f();
> +int g();
> +void h() {
> + switch (a) {
> + case 0:
> + case 56:
> + case 57:
> + break;
> + case 58:
> + case 59:
> + case 61:
> + case 62:
> + c();
> + case 64:
> + case 63:
> + d();
> + case 66:
> + case 65:
> + d();
> + case 68:
> + case 67:
> + d();
> + case 69:
> + case 70:
> + d();
> + case 71:
> + case 72:
> + case 88:
> + case 87:
> + d();
> + case 90:
> + case 89:
> + d();
> + case 92:
> + case 1:
> + d();
> + case 93:
> + case 73:
> + case 4:
> + e();
> + case 76:
> + case 5:
> + f();
> + case 7:
> + case 8:
> + case 84:
> + case 85:
> + break;
> + case 6:
> + case 299:
> + case 9:
> + case 80:
> + case 2:
> + case 3:
> + e();
> + default:
> + g();
> + }
> +}
