On Thu, Apr 27, 2017 at 10:09 AM, Daniel Santos <daniel.san...@pobox.com> wrote:
> Adds the predicates save_multiple and restore_multiple to predicates.md,
> which are used by following patterns in sse.md:
>
> * save_multiple - insn that calls a save stub
> * restore_multiple - call_insn that calls a save stub and returns to the
> function to allow a sibling call (which should typically offer better
> optimization than the restore stub as the tail call)
> * restore_multiple_and_return - a jump_insn that returns from the
> function as a tail-call.
> * restore_multiple_leave_return - like the above, but restores the frame
> pointer before returning.
>
> Signed-off-by: Daniel Santos <daniel.san...@pobox.com>
> ---
> gcc/config/i386/predicates.md | 155
> ++++++++++++++++++++++++++++++++++++++++++
> gcc/config/i386/sse.md | 37 ++++++++++
> 2 files changed, 192 insertions(+)
>
> diff --git a/gcc/config/i386/predicates.md b/gcc/config/i386/predicates.md
> index 8f250a2e720..36fe8abc3f4 100644
> --- a/gcc/config/i386/predicates.md
> +++ b/gcc/config/i386/predicates.md
> @@ -1657,3 +1657,158 @@
> (ior (match_operand 0 "register_operand")
> (and (match_code "const_int")
> (match_test "op == constm1_rtx"))))
> +
> +;; Return true if:
> +;; 1. first op is a symbol reference,
> +;; 2. >= 13 operands, and
> +;; 3. operands 2 to end is one of:
> +;; a. save a register to a memory location, or
> +;; b. restore stack pointer.
> +(define_predicate "save_multiple"
> + (match_code "parallel")
> +{
> + const unsigned nregs = XVECLEN (op, 0);
> + rtx head = XVECEXP (op, 0, 0);
> + unsigned i;
> +
> + if (GET_CODE (head) != USE)
> + return false;
> + else
> + {
> + rtx op0 = XEXP (head, 0);
> + if (op0 == NULL_RTX || GET_CODE (op0) != SYMBOL_REF)
> + return false;
> + }
> +
> + if (nregs < 13)
> + return false;
> +
> + for (i = 2; i < nregs; i++)
> + {
> + rtx e, src, dest;
> +
> + e = XVECEXP (op, 0, i);
> +
> + switch (GET_CODE (e))
> + {
> + case SET:
> + src = SET_SRC (e);
> + dest = SET_DEST (e);
> +
> + /* storing a register to memory. */
> + if (GET_CODE (src) == REG && GET_CODE (dest) == MEM)
Please use REG_P (...) and MEM_P (...) - and possible others -
predicates in the code.
> + {
> + rtx addr = XEXP (dest, 0);
> +
> + /* Good if dest address is in RAX. */
> + if (GET_CODE (addr) == REG
> + && REGNO (addr) == AX_REG)
> + continue;
> +
> + /* Good if dest address is offset of RAX. */
> + if (GET_CODE (addr) == PLUS
> + && GET_CODE (XEXP (addr, 0)) == REG
> + && REGNO (XEXP (addr, 0)) == AX_REG)
> + continue;
> + }
> + break;
> +
> + default:
> + break;
> + }
> + return false;
> + }
> + return true;
> +})
> +
> +;; Return true if:
> +;; * first op is (return) or a a use (symbol reference),
> +;; * >= 14 operands, and
> +;; * operands 2 to end are one of:
> +;; - restoring a register from a memory location that's an offset of RSI.
> +;; - clobbering a reg
> +;; - adjusting SP
> +(define_predicate "restore_multiple"
> + (match_code "parallel")
> +{
> + const unsigned nregs = XVECLEN (op, 0);
> + rtx head = XVECEXP (op, 0, 0);
> + unsigned i;
> +
> + switch (GET_CODE (head))
> + {
> + case RETURN:
> + i = 3;
> + break;
> +
> + case USE:
> + {
> + rtx op0 = XEXP (head, 0);
> +
> + if (op0 == NULL_RTX || GET_CODE (op0) != SYMBOL_REF)
> + return false;
> +
> + i = 1;
> + break;
> + }
> +
> + default:
> + return false;
> + }
> +
> + if (nregs < i + 12)
> + return false;
> +
> + for (; i < nregs; i++)
> + {
> + rtx e, src, dest;
> +
> + e = XVECEXP (op, 0, i);
> +
> + switch (GET_CODE (e))
> + {
> + case CLOBBER:
> + continue;
I don't see where CLOBBER is genreated in ix86_emit_outlined_ms2sysv_restore.
> +
> + case SET:
> + src = SET_SRC (e);
> + dest = SET_DEST (e);
> +
> + /* Restoring a register from memory. */
> + if (GET_CODE (src) == MEM && GET_CODE (dest) == REG)
> + {
> + rtx addr = XEXP (src, 0);
> +
> + /* Good if src address is in RSI. */
> + if (GET_CODE (addr) == REG
> + && REGNO (addr) == SI_REG)
> + continue;
> +
> + /* Good if src address is offset of RSI. */
> + if (GET_CODE (addr) == PLUS
> + && GET_CODE (XEXP (addr, 0)) == REG
> + && REGNO (XEXP (addr, 0)) == SI_REG)
> + continue;
> +
> + /* Good if adjusting stack pointer. */
> + if (GET_CODE (dest) == REG
> + && REGNO (dest) == SP_REG
> + && GET_CODE (src) == PLUS
> + && GET_CODE (XEXP (src, 0)) == REG
> + && REGNO (XEXP (src, 0)) == SP_REG)
> + continue;
> + }
> +
> + /* Restoring stack pointer from another register. */
> + if (GET_CODE (dest) == REG && REGNO (dest) == SP_REG
> + && GET_CODE (src) == REG)
> + continue;
> + break;
> +
> + default:
> + break;
> + }
> + return false;
> + }
> + return true;
> +})
I think that the above functions should check only if the function is
storing/restoring correct registers, all other RTXes should be
explicitly written in the insn patterns.
> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
> index e8ccb1e10c3..c9fe7274def 100644
> --- a/gcc/config/i386/sse.md
> +++ b/gcc/config/i386/sse.md
> @@ -19997,3 +19997,40 @@
> (match_operand:VI48_512 1 "nonimmediate_operand" "vm")))]
> "TARGET_AVX512VPOPCNTDQ"
> "vpopcnt<ssemodesuffix>\t{%1, %0<mask_operand2>|%0<mask_operand2>, %1}")
> +
> +;; Save multiple registers out-of-line.
> +(define_insn "save_multiple<mode>"
> + [(match_parallel 0 "save_multiple"
> + [(use (match_operand:P 1 "symbol_operand"))
> + (const_int 0)
> + ])]
> + "TARGET_SSE && TARGET_64BIT"
> + "call\t%P1")
You probably don't need a (const_int 0) tag. According to the
documentation, RTX matching guarantees subexpression match, so in the
predicate you should check only stores of registers (as suggested
above).
> +;; Restore multiple registers out-of-line.
> +(define_insn "restore_multiple<mode>"
> + [(match_parallel 0 "restore_multiple"
> + [(use (match_operand:P 1 "symbol_operand"))])]
> + "TARGET_SSE && TARGET_64BIT"
> + "call\t%P1")
> +
> +;; Restore multiple registers out-of-line and return.
> +(define_insn "restore_multiple_and_return<mode>"
> + [(match_parallel 0 "restore_multiple"
> + [(return)
> + (use (match_operand:P 1 "symbol_operand"))
> + (const_int 0)
> + ])]
> + "TARGET_SSE && TARGET_64BIT"
> + "jmp\t%P1")
No need for (const_int 0) tag.
> +;; Restore multiple registers out-of-line when hard frame pointer is used,
> +;; perform the leave operation prior to returning (from the function).
> +(define_insn "restore_multiple_leave_return<mode>"
> + [(match_parallel 0 "restore_multiple"
> + [(return)
> + (use (match_operand:P 1 "symbol_operand"))
> + (const_int 1)
> + ])]
> + "TARGET_SSE && TARGET_64BIT"
> + "jmp\t%P1")
You will have to write out all sub-RTXes of the "leave" pattern,
including clobber.
I'd recommend that in the predicate, you check match_parallel from the
bottom up, since subexpressions on the top are already matched, and
you can have different number of subexpressions at the top.
Uros.
