On Thu, Apr 27, 2017 at 10:09 AM, Daniel Santos <daniel.santos@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.santos@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.