* config/i386/i386.c (ix86_build_builtin_va_list): Initialize
va_list_{g,f}pr_counter_field.
(ix86_setup_incoming_varargs): Don't do anything if reg_save
area will not be used. Only save registers that tree-stdarg.c
detected they need saving.
(ix86_va_start): Don't set up fields that won't be used.
* config/rs6000/rs6000.c (rs6000_build_builtin_va_list): Initialize
va_list_{g,f}pr_counter_field.
(setup_incoming_varargs): Don't do anything if reg_save
area will not be used. Only save registers that tree-stdarg.c
detected they need saving.
(rs6000_va_start): Don't set up fields that won't be used.
* config/alpha/alpha.c: Include tree-flow.h and tree-stdarg.h.
(alpha_build_builtin_va_list): Initialize va_list_gpr_counter_field.
(va_list_skip_additions, alpha_stdarg_optimize_hook): New functions.
(TARGET_STDARG_OPTIMIZE_HOOK): Define.
* gcc.dg/tree-ssa/stdarg-1.c: New test.
* gcc.dg/tree-ssa/stdarg-2.c: New test.
* gcc.dg/tree-ssa/stdarg-3.c: New test.
* gcc.dg/tree-ssa/stdarg-4.c: New test.
* gcc.dg/tree-ssa/stdarg-5.c: New test.
* gcc.c-torture/execute/stdarg-4.c: New test.