On Thu, Mar 2, 2023 at 11:21 AM Richard Sandiford via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> convert_memory_address_addr_space_1 has two modes: one in which it
> tries to create a self-contained RTL expression (which might fail)
> and one in which it can emit new instructions where necessary.
>
> When handling a CONST, the function recurses into the CONST's
> operand and then constifies the result. But that's only valid if
> the result is still a self-contained expression. If new instructions
> have been emitted, the expression will refer to the (non-constant)
> results of those instructions.
>
> In the PR, this caused us to emit a nonsensical (const (reg ...))
> REG_EQUAL note.
>
> Tested on aarch64-linux-gnu & x86_64-linux-gnu. OK to install?
OK.
Thanks,
Richard.
> Richard
>
>
> gcc/
> PR tree-optimization/108603
> * explow.cc (convert_memory_address_addr_space_1): Only wrap
> the result of a recursive call in a CONST if no instructions
> were emitted.
>
> gcc/testsuite/
> PR tree-optimization/108603
> * gcc.target/aarch64/sve/pr108603.c: New test.
> ---
> gcc/explow.cc | 11 ++++++++---
> gcc/testsuite/gcc.target/aarch64/sve/pr108603.c | 8 ++++++++
> 2 files changed, 16 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/pr108603.c
>
> diff --git a/gcc/explow.cc b/gcc/explow.cc
> index 83439b32abe..32e9498ee07 100644
> --- a/gcc/explow.cc
> +++ b/gcc/explow.cc
> @@ -349,9 +349,14 @@ convert_memory_address_addr_space_1 (scalar_int_mode
> to_mode ATTRIBUTE_UNUSED,
> return temp;
>
> case CONST:
> - temp = convert_memory_address_addr_space_1 (to_mode, XEXP (x, 0), as,
> - true, no_emit);
> - return temp ? gen_rtx_CONST (to_mode, temp) : temp;
> + {
> + auto *last = no_emit ? nullptr : get_last_insn ();
> + temp = convert_memory_address_addr_space_1 (to_mode, XEXP (x, 0), as,
> + true, no_emit);
> + if (temp && (no_emit || last == get_last_insn ()))
> + return gen_rtx_CONST (to_mode, temp);
> + return temp;
> + }
>
> case PLUS:
> case MULT:
> diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr108603.c
> b/gcc/testsuite/gcc.target/aarch64/sve/pr108603.c
> new file mode 100644
> index 00000000000..a2aea9f0b12
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/aarch64/sve/pr108603.c
> @@ -0,0 +1,8 @@
> +/* { dg-options "-O2 -mabi=ilp32 -fdata-sections" } */
> +
> +int a[128];
> +long long *p;
> +void f() {
> + for (long i = 0; i < sizeof(long); i++)
> + p[i] = a[i];
> +}
> --
> 2.25.1
>
