X86_64: Enable support for next generation AMD Zen3 CPU.

X86_64: Enable support for next generation AMD Zen3 CPU.

2020-12-03  Venkataramanan Kumar  <Venkataramanan.Kumar@amd.com>
	    Sharavan Kumar  <Shravan.Kumar@amd.com>

gcc/ChangeLog:

	* common/config/i386/cpuinfo.h (get_amd_cpu) recognize znver3.
	* common/config/i386/i386-common.c (processor_names): Add
	znver3.
	(processor_alias_table): Add znver3 and AMDFAM19H entry.
	* common/config/i386/i386-cpuinfo.h (processor_types): Add
	AMDFAM19H.
	(processor_subtypes): AMDFAM19H_ZNVER3.
	* config.gcc (i[34567]86-*-linux* | ...): Likewise.
	* config/i386/driver-i386.c: (host_detect_local_cpu): Let
	-march=native recognize znver3 processors.
	* config/i386/i386-c.c (ix86_target_macros_internal): Add
	znver3.
	* config/i386/i386-options.c (m_znver3): New definition.
	(m_ZNVER): Include m_znver3.
	(processor_cost_table): Add znver3.
	* config/i386/i386.c (ix86_reassociation_width): Likewise.
	* config/i386/i386.h (TARGET_znver3): New definition.
	(enum processor_type): Add PROCESSOR_ZNVER3.
	* config/i386/i386.md (define_attr "cpu"): Add znver3.
	* config/i386/x86-tune-sched.c: (ix86_issue_rate): Likewise.
	(ix86_adjust_cost): Likewise.
	* config/i386/x86-tune.def (X86_TUNE_AVOID_256FMA_CHAINS:
	Likewise.
	* config/i386/znver1.md: Add new reservations for znver3.
	* doc/extend.texi: Add details about znver3.
	* doc/invoke.texi: Likewise.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/funcspec-56.inc: Handle new march.
	* g++.target/i386/mv29.C: New file.