On Thu, 19 Feb 2015, Tom de Vries wrote: > On 19-02-15 11:29, Tom de Vries wrote: > > Hi, > > > > I'm posting this patch series for stage1: > > - 0001-Disable-lang_hooks.gimplify_expr-in-free_lang_data.patch > > - 0002-Add-gimple_find_sub_bbs.patch > > - 0003-Factor-optimize_va_list_gpr_fpr_size-out-of-pass_std.patch > > - 0004-Handle-internal_fn-in-operand_equal_p.patch > > - 0005-Postpone-expanding-va_arg-until-pass_stdarg.patch > > > > The patch series - based on Michael's initial patch - postpones expanding > > va_arg > > until pass_stdarg, which makes pass_stdarg more robust. > > > > Bootstrapped and reg-tested on x86_64 using all languages, with unix/ and > > unix/-m32 testing. > > > > I'll post the patches in reply to this email. > > > > This patch postpones expanding va_arg until pass_stdarg. > > We add a new internal function IFN_VA_ARG. During gimplification, we map > VA_ARG_EXPR onto a CALL_EXPR with IFN_VA_ARG, which is then gimplified in to a > gimple_call. At pass_stdarg, we expand the IFN_VA_ARG gimple_call into actual > code. > > There are a few implementation details worth mentioning: > - passing the type beyond gimplification is done by adding a NULL pointer- > to-type to IFN_VA_ARG. > - there is special handling for IFN_VA_ARG that would be most suited to be > placed in gimplify_va_arg_expr. However, that function lacks the scope for > the special handling, so it's placed awkwardly in gimplify_modify_expr. > - there's special handling in case the va_arg type is variable-sized. > gimplify_modify_expr adds a WITH_SIZE_EXPR to the CALL_EXPR IFN_VA_ARG for > variable-sized types. However, this is gimplified into a gimple_call which > does not have the possibility to wrap it's result in a WITH_SIZE_EXPR. So > we're adding the size argument of the WITH_SIZE_EXPR as argument to > IFN_VA_ARG, and at expansion in pass_stdarg, wrap the result of the > gimplification of IFN_VA_ARG in a WITH_SIZE_EXPR, such that the subsequent > gimplify_assign will generate a memcpy if necessary. > - when gimplifying the va_arg argument ap, it may not be addressable. So > gimplification will generate a copy ap.1 = ap, and use &ap.1 as argument. > This means that we have to copy back the ap.1 value to ap after IFN_VA_ARG. > The copy is classified by the va_list_gpr/fpr_size optimization as an > escape, so it inhibits optimization. The tree-ssa/stdarg-2.c f15 update is > because of that. > > OK for stage1?
Looks mostly good, though it looks like with -O0 this doesn't delay lowering of va-arg and thus won't "fix" offloading. Can you instead introduce a PROP_gimple_lva, provide it by the stdarg pass and add a pass_lower_vaarg somewhere where pass_lower_complex_O0 is run that runs of !PROP_gimple_lva (and also provides it), and require PROP_gimple_lva by pass_expand? (just look for PROP_gimple_lcx for the complex stuff to get an idea what needs to be touched) Thanks, Richard.
