On Thu, 2021-06-17 at 10:19 -0500, Bill Schmidt via Gcc-patches wrote:
> 2021-03-05 Bill Schmidt <wschm...@linux.ibm.com>
>
Hi,
> gcc/
> * config/rs6000/rs6000-call.c (new_cpu_expand_builtin):
> Implement.
ok
> ---
> gcc/config/rs6000/rs6000-call.c | 100 ++++++++++++++++++++++++++++++++
> 1 file changed, 100 insertions(+)
>
> diff --git a/gcc/config/rs6000/rs6000-call.c b/gcc/config/rs6000/rs6000-call.c
> index 754cd46b1c1..ad3e6a4bbe5 100644
> --- a/gcc/config/rs6000/rs6000-call.c
> +++ b/gcc/config/rs6000/rs6000-call.c
> @@ -14604,6 +14604,106 @@ static rtx
> new_cpu_expand_builtin (enum rs6000_gen_builtins fcode,
> tree exp ATTRIBUTE_UNUSED, rtx target)
> {
> + /* __builtin_cpu_init () is a nop, so expand to nothing. */
> + if (fcode == RS6000_BIF_CPU_INIT)
> + return const0_rtx;
> +
> + if (target == 0 || GET_MODE (target) != SImode)
> + target = gen_reg_rtx (SImode);
> +
> +#ifdef TARGET_LIBC_PROVIDES_HWCAP_IN_TCB
> + tree arg = TREE_OPERAND (CALL_EXPR_ARG (exp, 0), 0);
> + /* Target clones creates an ARRAY_REF instead of STRING_CST, convert it
> back
> + to a STRING_CST. */
> + if (TREE_CODE (arg) == ARRAY_REF
> + && TREE_CODE (TREE_OPERAND (arg, 0)) == STRING_CST
> + && TREE_CODE (TREE_OPERAND (arg, 1)) == INTEGER_CST
> + && compare_tree_int (TREE_OPERAND (arg, 1), 0) == 0)
> + arg = TREE_OPERAND (arg, 0);
> +
> + if (TREE_CODE (arg) != STRING_CST)
> + {
> + error ("builtin %qs only accepts a string argument",
> + rs6000_builtin_info_x[(size_t) fcode].bifname);
> + return const0_rtx;
> + }
> +
> + if (fcode == RS6000_BIF_CPU_IS)
> + {
> + const char *cpu = TREE_STRING_POINTER (arg);
> + rtx cpuid = NULL_RTX;
> + for (size_t i = 0; i < ARRAY_SIZE (cpu_is_info); i++)
> + if (strcmp (cpu, cpu_is_info[i].cpu) == 0)
> + {
> + /* The CPUID value in the TCB is offset by _DL_FIRST_PLATFORM. */
> + cpuid = GEN_INT (cpu_is_info[i].cpuid + _DL_FIRST_PLATFORM);
> + break;
> + }
ok
> + if (cpuid == NULL_RTX)
> + {
> + /* Invalid CPU argument. */
> + error ("cpu %qs is an invalid argument to builtin %qs",
> + cpu, rs6000_builtin_info_x[(size_t) fcode].bifname);
> + return const0_rtx;
> + }
> +
> + rtx platform = gen_reg_rtx (SImode);
> + rtx tcbmem = gen_const_mem (SImode,
> + gen_rtx_PLUS (Pmode,
> + gen_rtx_REG (Pmode, TLS_REGNUM),
> + GEN_INT (TCB_PLATFORM_OFFSET)));
> + emit_move_insn (platform, tcbmem);
> + emit_insn (gen_eqsi3 (target, platform, cpuid));
> + }
> + else if (fcode == RS6000_BIF_CPU_SUPPORTS)
> + {
> + const char *hwcap = TREE_STRING_POINTER (arg);
> + rtx mask = NULL_RTX;
> + int hwcap_offset;
> + for (size_t i = 0; i < ARRAY_SIZE (cpu_supports_info); i++)
> + if (strcmp (hwcap, cpu_supports_info[i].hwcap) == 0)
> + {
> + mask = GEN_INT (cpu_supports_info[i].mask);
> + hwcap_offset = TCB_HWCAP_OFFSET (cpu_supports_info[i].id);
> + break;
> + }
> + if (mask == NULL_RTX)
> + {
> + /* Invalid HWCAP argument. */
> + error ("%s %qs is an invalid argument to builtin %qs",
> + "hwcap", hwcap,
> + rs6000_builtin_info_x[(size_t) fcode].bifname);
> + return const0_rtx;
> + }
> +
> + rtx tcb_hwcap = gen_reg_rtx (SImode);
> + rtx tcbmem = gen_const_mem (SImode,
> + gen_rtx_PLUS (Pmode,
> + gen_rtx_REG (Pmode, TLS_REGNUM),
> + GEN_INT (hwcap_offset)));
> + emit_move_insn (tcb_hwcap, tcbmem);
> + rtx scratch1 = gen_reg_rtx (SImode);
> + emit_insn (gen_rtx_SET (scratch1, gen_rtx_AND (SImode, tcb_hwcap,
> mask)));
> + rtx scratch2 = gen_reg_rtx (SImode);
> + emit_insn (gen_eqsi3 (scratch2, scratch1, const0_rtx));
> + emit_insn (gen_rtx_SET (target, gen_rtx_XOR (SImode, scratch2,
> const1_rtx)));
> + }
> + else
> + gcc_unreachable ();
> +
> + /* Record that we have expanded a CPU builtin, so that we can later
> + emit a reference to the special symbol exported by LIBC to ensure we
> + do not link against an old LIBC that doesn't support this feature. */
> + cpu_builtin_p = true;
> +
> +#else
> + warning (0, "builtin %qs needs GLIBC (2.23 and newer) that exports
> hardware "
> + "capability bits", rs6000_builtin_info_x[(size_t) fcode].bifname);
> +
This seems OK.
It appears to comply with the documentation at least :-)
"If GCC was configured to use a GLIBC before 2.23, the built-in
function __builtin_cpu_is always returns a 0 and the compiler
issues a warning."
ok
lgtm,
thanks
-Will
> + /* For old LIBCs, always return FALSE. */
> + emit_move_insn (target, GEN_INT (0));
> +#endif /* TARGET_LIBC_PROVIDES_HWCAP_IN_TCB */
> +
> return target;
> }
>
