[PATCH] PR target/50038 fix: redundant zero extensions removal

[Ilya Enkovich]

Hi,

Here is a patch which fixes redundant zero extensions problem. Issue
is resolved by expanding implicit_zee pass functionality to cover zero
and sign extends of different modes. Could please someone review it?

Bootstrapped and checked on linux-x86_64.

Thanks,
Ilya
---
2011-11-01  Enkovich Ilya  <ilya.enkovich@intel.com>

	PR target/50038
	* implicit-zee.c (ext_cand): New.
	(ext_cand_pool): Likewise.
	(add_ext_candidate): New.
	(zee_init): New.
	(zee_cleanup): New.
	(get_reg_di): Removed.
	(combine_set_zero_extend): Get extend candidate as new parameter.
	Now handle sign extend cases and other modes.
	(transform_ifelse): Likewise.
	(merge_def_and_ze): Likewise.
	(combine_reaching_defs): Change parameter type.
	(zero_extend_info): Changed insn_list type.
	(add_removable_zero_extend): Relaxed mode and code filter.
	(find_removable_zero_extends): Changed return type.
	(find_and_remove_ze): Var type changes.
	(rest_of_handle_zee): Init and cleanup added.

	* i386.c (ix86_option_override_internal): set flag_zee for
	32 bit platform.
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