Hi Richard, > On 05/20/2013 09:55 AM, Kyrylo Tkachov wrote: > > For example, a setup like: > > > > (define_attr "predicated" "yes,no" (const_string "no")) > > > > (define_attr "control_attr" "yes,no" (const_string "yes")) > > > > > > (define_attr "enabled" "no,yes" > > (cond [(and (eq_attr "control_attr" "no") > > (and (eq_attr "predicated" "yes") > > (eq_attr "TARGET_RESTRICT_CE" "no"))) > > (const_string "no")] > > (const_string "yes")) > > > > (define_cond_exec > > [(match_operator 0 "arm_comparison_operator" > > [(match_operand 1 "cc_register" "") > > (const_int 0)])] > > "" > > "" > > [(set_attr "predicated" "yes")] // <<<< New field > > ) > > > > (define_insn ... > > [(set_attr "predicable" "yes") > > (set_attr "control_attr" "yes,no")]) // <<<< disables predicated > version of > > We have a new define_subst which may help here. I *think* that > define_cond_exec is (or is nearly) a subset of define_subst. On my > medium term > to-do list is to support define_cond_exec within gensupport via the > define_subst infrastructure, removing everything except the actual > parsing of > define_cond_exec.
An clearer example of what I'm trying to achieve can be found here: http://gcc.gnu.org/ml/gcc-patches/2013-05/msg01139.html I've been trying to wrap my head around define_subst, and it was considered initially, but from the online documentation (http://gcc.gnu.org/onlinedocs/gccint/Define-Subst.html#Define-Subst) I couldn't think of a way to use it. What I want essentially, is to disable the cond_exec variant of an insn based on some variable. This stems from the fact that the "predicable" attribute cannot depend on anything else (has to be a compile-compile time constant). > > Your "predicated" attribute could be mapped to a define_subst > substitution. > You could expose this via a true attribute, but I'm not 100% certain > that you'd > need to do so. > > I havn't thought about all of the ramifications here, but I'd be > interested to > hear about your thoughts or experiments down this line. Could you point me to any decent example of define_subst usage apart from the documentation? >From what I can see, define_subst performs RTL transformations, but doesn't say anything about the attributes Thanks, Kyrill > > > r~
