Use visitor pattern for "maint print c-tdesc"

Target description can be modeled as a tree, the target description
is the root node, features are children nodes, registers and types are
grand-children nodes.  So command "maint print c-tdesc" in effect
traverse/visit each node, and print them in c.  This can be
implemented by visitor pattern, this is the first reason.  Secondly,
I want to this command prints c files in a different way for some
specific xml files, but still print c files the same way for the rest
of xml files.  Third, I even want to print xml files from target
descriptions, so that GDBserver can use it to reply GDB's query
qXfer:features:read:target.xml.

gdb:

2017-07-26  Yao Qi  <yao.qi@linaro.org>

	* target-descriptions.c (tdesc_element_visitor): New class.
	(tdesc_element): New class.
	(tdesc_reg): Inherit from tdesc_element.
	(tdesc_reg::accept): New function.
	(tdesc_type): Inherit from tdesc_element.
	(tdesc_type::accept): New function.
	(tdesc_feature): Inherit from tdesc_element.
	(tdesc_feature::accept): New function.
	(target_desc): Inherit from tdesc_element.
	(target_desc::target_desc): New.
	(target_desc::~target_desc): New.
	(target_desc::accept): New.
	(allocate_target_description): Use new.
	(free_target_description): Use delete.
	(print_c_tdesc): New class.
	(maint_print_c_tdesc_cmd): Adjust.

	* features/aarch64.c: Re-generated.
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	* features/arm/arm-with-m-vfp-d16.c: Re-generated.
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	* features/arm/arm-with-vfpv2.c: Re-generated.
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	* features/i386/amd64-avx-avx512.c: Re-generated.
	* features/i386/amd64-avx-avx512-linux.c: Re-generated.
	* features/i386/amd64-avx.c: Re-generated.
	* features/i386/amd64-avx-linux.c: Re-generated.
	* features/i386/amd64-avx-mpx-avx512-pku.c: Re-generated.
	* features/i386/amd64-avx-mpx-avx512-pku-linux.c: Re-generated.
	* features/i386/amd64-avx-mpx.c: Re-generated.
	* features/i386/amd64-avx-mpx-linux.c: Re-generated.
	* features/i386/amd64.c: Re-generated.
	* features/i386/amd64-linux.c: Re-generated.
	* features/i386/amd64-mpx.c: Re-generated.
	* features/i386/amd64-mpx-linux.c: Re-generated.
	* features/i386/i386-avx-avx512.c: Re-generated.
	* features/i386/i386-avx-avx512-linux.c: Re-generated.
	* features/i386/i386-avx.c: Re-generated.
	* features/i386/i386-avx-linux.c: Re-generated.
	* features/i386/i386-avx-mpx-avx512-pku.c: Re-generated.
	* features/i386/i386-avx-mpx-avx512-pku-linux.c: Re-generated.
	* features/i386/i386-avx-mpx.c: Re-generated.
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	* features/i386/i386-mpx.c: Re-generated.
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	* features/i386/x32-avx-avx512.c: Re-generated.
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	* features/mips-dsp-linux.c: Re-generated.
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	* features/nds32.c: Re-generated.
	* features/nios2.c: Re-generated.
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	* features/rs6000/powerpc-32.c: Re-generated.
	* features/rs6000/powerpc-32l.c: Re-generated.
	* features/rs6000/powerpc-403.c: Re-generated.
	* features/rs6000/powerpc-403gc.c : Re-generated.
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	* features/rs6000/powerpc-7400.c: Re-generated.
	* features/rs6000/powerpc-750.c: Re-generated.
	* features/rs6000/powerpc-860.c: Re-generated.
	* features/rs6000/powerpc-altivec32.c: Re-generated.
	* features/rs6000/powerpc-altivec32l.c: Re-generated.
	* features/rs6000/powerpc-altivec64.c: Re-generated.
	* features/rs6000/powerpc-altivec64l.c: Re-generated.
	* features/rs6000/powerpc-cell32l.c: Re-generated.
	* features/rs6000/powerpc-cell64l.c: Re-generated.
	* features/rs6000/powerpc-e500.c: Re-generated.
	* features/rs6000/powerpc-e500l.c: Re-generated.
	* features/rs6000/powerpc-isa205-32l.c: Re-generated.
	* features/rs6000/powerpc-isa205-64l.c: Re-generated.
	* features/rs6000/powerpc-isa205-altivec32l.c: Re-generated.
	* features/rs6000/powerpc-isa205-altivec64l.c: Re-generated.
	* features/rs6000/powerpc-isa205-vsx32l.c: Re-generated.
	* features/rs6000/powerpc-isa205-vsx64l.c: Re-generated.
	* features/rs6000/powerpc-vsx32.c: Re-generated.
	* features/rs6000/powerpc-vsx32l.c: Re-generated.
	* features/rs6000/powerpc-vsx64.c: Re-generated.
	* features/rs6000/powerpc-vsx64l.c: Re-generated.
	* features/rs6000/rs6000.c: Re-generated.
	* features/s390-linux32.c: Re-generated.
	* features/s390-linux32v1.c: Re-generated.
	* features/s390-linux32v2.c: Re-generated.
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	* features/s390-linux64v1.c: Re-generated.
	* features/s390-linux64v2.c: Re-generated.
	* features/s390-te-linux64.c: Re-generated.
	* features/s390-tevx-linux64.c: Re-generated.
	* features/s390-vx-linux64.c: Re-generated.
	* features/s390x-linux64.c: Re-generated.
	* features/s390x-linux64v1.c: Re-generated.
	* features/s390x-linux64v2.c: Re-generated.
	* features/s390x-te-linux64.c: Re-generated.
	* features/s390x-tevx-linux64.c: Re-generated.
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	* features/sparc/sparc32-solaris.c: Re-generated.
	* features/sparc/sparc64-solaris.c: Re-generated.
	* features/tic6x-c62x.c: Re-generated.
	* features/tic6x-c62x-linux.c: Re-generated.
	* features/tic6x-c64x.c: Re-generated.
	* features/tic6x-c64x-linux.c: Re-generated.
	* features/tic6x-c64xp.c: Re-generated.
	* features/tic6x-c64xp-linux.c: Re-generated.

1 files changed, 4 insertions, 4 deletions

diff --git a/gdb/features/rs6000/powerpc-vsx64.c b/gdb/features/rs6000/powerpc-vsx64.c
index ca0232386b8..30953c539c1 100644
--- a/gdb/features/rs6000/powerpc-vsx64.c
+++ b/gdb/features/rs6000/powerpc-vsx64.c
@@ -10,12 +10,10 @@ static void
 initialize_tdesc_powerpc_vsx64 (void)
 {
   struct target_desc *result = allocate_target_description ();
-  struct tdesc_feature *feature;
-  struct tdesc_type *field_type;
-  struct tdesc_type *type;
-
   set_tdesc_architecture (result, bfd_scan_arch ("powerpc:common64"));
 
+  struct tdesc_feature *feature;
+
   feature = tdesc_create_feature (result, "org.gnu.gdb.power.core");
   tdesc_create_reg (feature, "r0", 0, 1, NULL, 64, "uint64");
   tdesc_create_reg (feature, "r1", 1, 1, NULL, 64, "uint64");
@@ -92,6 +90,7 @@ initialize_tdesc_powerpc_vsx64 (void)
   tdesc_create_reg (feature, "fpscr", 70, 1, "float", 32, "int");
 
   feature = tdesc_create_feature (result, "org.gnu.gdb.power.altivec");
+  struct tdesc_type *field_type;
   field_type = tdesc_named_type (feature, "ieee_single");
   tdesc_create_vector (feature, "v4f", field_type, 4);
 
@@ -104,6 +103,7 @@ initialize_tdesc_powerpc_vsx64 (void)
   field_type = tdesc_named_type (feature, "int8");
   tdesc_create_vector (feature, "v16i8", field_type, 16);
 
+  struct tdesc_type *type;
   type = tdesc_create_union (feature, "vec128");
   field_type = tdesc_named_type (feature, "uint128");
   tdesc_add_field (type, "uint128", field_type);