Hi!
The last peephole I've recently added is as the testcase shows fundamentally
incompatible with non-commutative operations, because we need to swap the
operands.
The pattern right before this one already is:
(define_peephole2
[(parallel [(set (match_operand:SWI 0 "register_operand")
(match_operator:SWI 2 "plusminuslogic_operator"
[(match_dup 0)
(match_operand:SWI 1 "memory_operand")]))
(clobber (reg:CC FLAGS_REG))])
(set (match_dup 1) (match_dup 0))
(set (reg FLAGS_REG) (compare (match_dup 0) (const_int 0)))]
"(TARGET_READ_MODIFY_WRITE || optimize_insn_for_size_p ())
&& GET_CODE (operands[2]) != MINUS
^^^^^^^^ disallow non-commutative plusminuslogic_operator
&& peep2_reg_dead_p (3, operands[0])
&& !reg_overlap_mentioned_p (operands[0], operands[1])
&& ix86_match_ccmode (peep2_next_insn (2),
GET_CODE (operands[2]) == PLUS
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no need to check for MINUS here
? CCGOCmode : CCNOmode)"
[(parallel [(set (match_dup 3) (match_dup 5))
(set (match_dup 1) (match_dup 4))])]
{
operands[3] = SET_DEST (PATTERN (peep2_next_insn (2)));
operands[4]
= gen_rtx_fmt_ee (GET_CODE (operands[2]), GET_MODE (operands[2]),
copy_rtx (operands[1]),
operands[0]);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ and here is where it swaps the operands,
^^^^^^^^^^^^^^ the memory originally in the last input is here as the first
input
operands[5]
= gen_rtx_COMPARE (GET_MODE (operands[3]),
copy_rtx (operands[4]),
const0_rtx);
})
The following patch handles the cmpelim peephole the same. Ok for trunk?
Unfortunately, I'm travelling and can't test it right now, Marek, do you
think you could bootstrap/regtest it for me? Thanks.
2018-05-14 Jakub Jelinek <ja...@redhat.com>
PR target/85756
* config/i386/i386.md: Disallow MINUS in last peephole for
mem {+,-,&,|,^}= x; mem != 0 after cmpelim optimization.
* gcc.c-torture/execute/pr85756.c: New test.
--- gcc/config/i386/i386.md.jj 2018-05-11 18:44:32.000000000 +0200
+++ gcc/config/i386/i386.md 2018-05-14 13:50:28.100482520 +0200
@@ -19397,11 +19397,11 @@
(set (match_dup 0) (match_dup 2))])
(set (match_dup 1) (match_dup 0))]
"(TARGET_READ_MODIFY_WRITE || optimize_insn_for_size_p ())
+ && GET_CODE (operands[2]) != MINUS
&& peep2_reg_dead_p (2, operands[0])
&& !reg_overlap_mentioned_p (operands[0], operands[1])
&& ix86_match_ccmode (peep2_next_insn (0),
- (GET_CODE (operands[2]) == PLUS
- || GET_CODE (operands[2]) == MINUS)
+ GET_CODE (operands[2]) == PLUS
? CCGOCmode : CCNOmode)"
[(parallel [(set (match_dup 3) (match_dup 5))
(set (match_dup 1) (match_dup 4))])]
--- gcc/testsuite/gcc.c-torture/execute/pr85756.c.jj 2018-05-14
13:50:44.384307289 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr85756.c 2018-05-14
13:48:17.000000000 +0200
@@ -0,0 +1,50 @@
+/* PR target/85756 */
+
+#if __CHAR_BIT__ == 8 && __SIZEOF_SHORT__ == 2 && __SIZEOF_INT__ == 4
+int a, c, *e, f, h = 10;
+short b;
+unsigned int p;
+
+__attribute__((noipa)) void
+bar (int a)
+{
+ asm volatile ("" : : "r" (a) : "memory");
+}
+
+void
+foo ()
+{
+ unsigned j = 1, m = 430523;
+ int k, n = 1, *l = &h;
+lab:
+ p = m;
+ m = -((~65535U | j) - n);
+ f = b << ~(n - 8);
+ n = (m || b) ^ f;
+ j = p;
+ if (p < m)
+ *l = k < 3;
+ if (!n)
+ l = &k;
+ if (c)
+ {
+ bar (a);
+ goto lab;
+ }
+ if (!*l)
+ *e = 1;
+}
+
+int
+main ()
+{
+ foo ();
+ return 0;
+}
+#else
+int
+main ()
+{
+ return 0;
+}
+#endif
Jakub
