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?