diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 004c7bb446f493099f3829879d119369ad61b0e8..068ddd90d1e741a442c6f4625953f109cae4cab4 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2017-05-17 Uros Bizjak <ubizjak@gmail.com> + + * doc/md.texi (Canonicalization of Instructions): Describe the + canonical form of instructions that inherently set a condition + code register. + 2017-05-17 Peter Bergner <bergner@vnet.ibm.com> PR middle-end/80775 diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index dde3644890e3de3612a487966e29395cd76cb670..e3daceacf52d8d067f05891598806d2820f22136 100644 --- a/gcc/doc/md.texi +++ b/gcc/doc/md.texi @@ -7257,6 +7257,25 @@ the operations as far as possible. For instance, For the @code{compare} operator, a constant is always the second operand if the first argument is a condition code register or @code{(cc0)}. +@item +For instructions that inherently set a condition code register, the +@code{compare} operator is always written as the first RTL expression of +the @code{parallel} instruction pattern. For example, + +@smallexample +(define_insn "" + [(set (reg:CCZ FLAGS_REG) + (compare:CCZ + (plus:SI + (match_operand:SI 1 "register_operand" "%r") + (match_operand:SI 2 "register_operand" "r")) + (const_int 0))) + (set (match_operand:SI 0 "register_operand" "=r") + (plus:SI (match_dup 1) (match_dup 2)))] + "" + "addl %0, %1, %2") +@end smallexample + @item An operand of @code{neg}, @code{not}, @code{mult}, @code{plus}, or @code{minus} is made the first operand under the same conditions as