Dynamically composite xml in reply to GDB

GDBserver still uses pre-generated target descriptions in order to
reply to GDB's query on target description (see xml-builtin-generated.c
in GDBserver build directory).  This patch teaches GDBserver to
create XML contents according to the target descriptions rather than
using pre-generated ones.

First, change target feature c files to pass the feature xml file
name to tdesc_create_feature, so that target description in GDBserver
can record them, and create XML contents from these features in
buffer, like

  ...
  <xi:include href="$FEATURE1_XML_NAME"/>
  <xi:include href="$FEATURE2_XML_NAME"/>
  ...

and send this buffer back to GDB.

gdb/gdbserver:

2017-05-24  Yao Qi  <yao.qi@linaro.org>

	* linux-x86-tdesc.c (i386_get_ipa_tdesc): Call
	set_tdesc_architecture and set_tdesc_osabi.  Don't set
	xmltarget field.
	* server.c (get_features_xml): Call tdesc_get_features_xml.
	* tdesc.c (set_tdesc_architecture): New function.
	(set_tdesc_osabi): New function.
	(tdesc_get_features_xml): New function.
	(tdesc_create_feature): Add one argument.
	* tdesc.h (struct target_desc) <features>: New field.
	<arch>: New field.
	<osabi>: New field.
	(target_desc::~target_desc): xfree arch, osabi, and
	features.
	(set_tdesc_architecture): Declare.
	(set_tdesc_osabi): Declare.
	(tdesc_get_features_xml): Declare.
	* target-descriptions.c (tdesc_create_feature): Add one
	argument.
	* target-descriptions.h (tdesc_create_feature): Update
	the declaration.

13 files changed, 106 insertions, 49 deletions

diff --git a/gdb/features/i386/32bit-avx.c b/gdb/features/i386/32bit-avx.c
index bae025d..2146e00 100644
--- a/gdb/features/i386/32bit-avx.c
+++ b/gdb/features/i386/32bit-avx.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_avx (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.avx");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.avx", "32bit-avx.xml");
   tdesc_create_reg (feature, "ymm0h", regnum++, 1, NULL, 128, "uint128");
   tdesc_create_reg (feature, "ymm1h", regnum++, 1, NULL, 128, "uint128");
   tdesc_create_reg (feature, "ymm2h", regnum++, 1, NULL, 128, "uint128");
diff --git a/gdb/features/i386/32bit-avx512.c b/gdb/features/i386/32bit-avx512.c
index ca15f8b..d36b4b0 100644
--- a/gdb/features/i386/32bit-avx512.c
+++ b/gdb/features/i386/32bit-avx512.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_avx512 (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.avx512");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.avx512", "32bit-avx512.xml");
   struct tdesc_type *field_type;
   field_type = tdesc_named_type (feature, "uint128");
   tdesc_create_vector (feature, "v2ui128", field_type, 2);
diff --git a/gdb/features/i386/32bit-core.c b/gdb/features/i386/32bit-core.c
index 8db91ab..72694b8 100644
--- a/gdb/features/i386/32bit-core.c
+++ b/gdb/features/i386/32bit-core.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_core (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.core");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.core", "32bit-core.xml");
   struct tdesc_type *field_type;
   struct tdesc_type *type;
   type = tdesc_create_flags (feature, "i386_eflags", 4);
diff --git a/gdb/features/i386/32bit-linux.c b/gdb/features/i386/32bit-linux.c
index 7535c55..9ba9ae1 100644
--- a/gdb/features/i386/32bit-linux.c
+++ b/gdb/features/i386/32bit-linux.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_linux (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.linux");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.linux", "32bit-linux.xml");
   regnum = 41;
   tdesc_create_reg (feature, "orig_eax", regnum++, 1, NULL, 32, "int");
   return regnum;
diff --git a/gdb/features/i386/32bit-mpx.c b/gdb/features/i386/32bit-mpx.c
index 9f1ae67..19fbae5 100644
--- a/gdb/features/i386/32bit-mpx.c
+++ b/gdb/features/i386/32bit-mpx.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_mpx (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.mpx");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.mpx", "32bit-mpx.xml");
   struct tdesc_type *field_type;
   struct tdesc_type *type;
   type = tdesc_create_struct (feature, "br128");
diff --git a/gdb/features/i386/32bit-pkeys.c b/gdb/features/i386/32bit-pkeys.c
index 86035ab..ee8208a 100644
--- a/gdb/features/i386/32bit-pkeys.c
+++ b/gdb/features/i386/32bit-pkeys.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_pkeys (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.pkeys");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.pkeys", "32bit-pkeys.xml");
   tdesc_create_reg (feature, "pkru", regnum++, 1, NULL, 32, "uint32");
   return regnum;
 }
diff --git a/gdb/features/i386/32bit-sse.c b/gdb/features/i386/32bit-sse.c
index 876c04d..d57cf49 100644
--- a/gdb/features/i386/32bit-sse.c
+++ b/gdb/features/i386/32bit-sse.c
@@ -14,7 +14,7 @@ create_feature_i386_32bit_sse (struct target_desc *result, long regnum)
 {
   struct tdesc_feature *feature;
 
-  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.sse");
+  feature = tdesc_create_feature (result, "org.gnu.gdb.i386.sse", "32bit-sse.xml");
   struct tdesc_type *field_type;
   field_type = tdesc_named_type (feature, "ieee_single");
   tdesc_create_vector (feature, "v4f", field_type, 4);
diff --git a/gdb/gdbserver/linux-x86-tdesc.c b/gdb/gdbserver/linux-x86-tdesc.c
index 06e5bf9..0dc5275 100644
--- a/gdb/gdbserver/linux-x86-tdesc.c
+++ b/gdb/gdbserver/linux-x86-tdesc.c
@@ -132,6 +132,12 @@ i386_get_ipa_tdesc (int idx)
   if (*tdesc == NULL)
     {
       *tdesc = new target_desc ();
+
+#ifndef IN_PROCESS_AGENT
+      set_tdesc_architecture (*tdesc, "i386");
+      set_tdesc_osabi (*tdesc, "GNU/Linux");
+#endif
+
       long regnum = 0;
 
       regnum = create_feature_i386_32bit_core (*tdesc, regnum);
@@ -162,35 +168,6 @@ i386_get_ipa_tdesc (int idx)
 #ifndef IN_PROCESS_AGENT
       static const char *expedite_regs_i386[] = { "ebp", "esp", "eip", NULL };
       (*tdesc)->expedite_regs = expedite_regs_i386;
-
-      switch (idx)
-	{
-	case X86_TDESC_MMX:
-	  (*tdesc)->xmltarget = "i386-mmx-linux.xml";
-	  break;
-	case X86_TDESC_SSE:
-	  (*tdesc)->xmltarget = "i386-linux.xml";
-	  break;
-	case X86_TDESC_AVX:
-	  (*tdesc)->xmltarget = "i386-avx-linux.xml";
-	  break;
-	case X86_TDESC_MPX:
-	  (*tdesc)->xmltarget = "i386-mpx-linux.xml";
-	  break;
-	case X86_TDESC_AVX_MPX:
-	  (*tdesc)->xmltarget = "i386-avx-mpx-linux.xml";
-	  break;
-	case X86_TDESC_AVX_AVX512:
-	  (*tdesc)->xmltarget = "i386-avx-avx512-linux.xml";
-	  break;
-	case X86_TDESC_AVX_MPX_AVX512_PKU:
-	  (*tdesc)->xmltarget = "i386-avx-mpx-avx512-pku-linux.xml";
-	  break;
-	default:
-	  internal_error (__FILE__, __LINE__,
-			  "unknown ipa tdesc index: %d", idx);
-	}
-
 #endif
     }
   return *tdesc;;
diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
index d0dcbee..f54ff46 100644
--- a/gdb/gdbserver/server.c
+++ b/gdb/gdbserver/server.c
@@ -810,12 +810,14 @@ get_features_xml (const char *annex)
      This variable is set up from the auto-generated
      init_registers_... routine for the current target.  */
 
-  if (desc->xmltarget != NULL && strcmp (annex, "target.xml") == 0)
+  if (strcmp (annex, "target.xml") == 0)
     {
-      if (*desc->xmltarget == '@')
-	return desc->xmltarget + 1;
+      const char *ret = tdesc_get_features_xml ((target_desc*) desc);
+
+      if (*ret == '@')
+	return ret + 1;
       else
-	annex = desc->xmltarget;
+	annex = ret;
     }
 
 #ifdef USE_XML
diff --git a/gdb/gdbserver/tdesc.c b/gdb/gdbserver/tdesc.c
index 686c76a..6b4c4b7 100644
--- a/gdb/gdbserver/tdesc.c
+++ b/gdb/gdbserver/tdesc.c
@@ -61,14 +61,70 @@ current_target_desc (void)
 
   return current_process ()->tdesc;
 }
+void
+set_tdesc_architecture (struct target_desc *target_desc,
+			const char *name)
+{
+  target_desc->arch = xstrdup (name);
+}
+
+void
+set_tdesc_osabi (struct target_desc *target_desc, const char *name)
+{
+  target_desc->osabi = xstrdup (name);
+}
+
+const char *
+tdesc_get_features_xml (target_desc *tdesc)
+{
+  /* Either .xmltarget or .features is not NULL.  */
+  gdb_assert (tdesc->xmltarget != NULL
+	      || (tdesc->features != NULL
+		  && tdesc->arch != NULL
+		  && tdesc->osabi != NULL));
+
+  if (tdesc->xmltarget == NULL)
+    {
+      std::string buffer ("@<?xml version=\"1.0\"?>");
+
+      buffer += "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">";
+      buffer += "<target>";
+      buffer += "<architecture>";
+      buffer += tdesc->arch;
+      buffer += "</architecture>";
+
+      buffer += "<osabi>";
+      buffer += tdesc->osabi;
+      buffer += "</osabi>";
+
+      char *xml;
+
+      for (int i = 0; VEC_iterate (char_ptr, tdesc->features, i, xml); i++)
+	{
+	  buffer += "<xi:include href=\"";
+	  buffer += xml;
+	  buffer += "\"/>";
+	}
+
+      buffer += "</target>";
+
+      tdesc->xmltarget = xstrdup (buffer.c_str ());
+    }
+
+  return tdesc->xmltarget;
+}
 #endif
 
 struct tdesc_type
 {};
 
 struct tdesc_feature *
-tdesc_create_feature (struct target_desc *tdesc, const char *name)
+tdesc_create_feature (struct target_desc *tdesc, const char *name,
+		      const char *xml)
 {
+#ifndef IN_PROCESS_AGENT
+  VEC_safe_push (char_ptr, tdesc->features, xstrdup (xml));
+#endif
   return tdesc;
 }
 
diff --git a/gdb/gdbserver/tdesc.h b/gdb/gdbserver/tdesc.h
index e64f0b3..c3ab30d 100644
--- a/gdb/gdbserver/tdesc.h
+++ b/gdb/gdbserver/tdesc.h
@@ -47,6 +47,12 @@ struct target_desc
      actual XML file to be used in place of "target.xml".  */
   const char *xmltarget = NULL;
 
+  VEC (char_ptr) *features = NULL;
+
+  const char *arch = NULL;
+
+  const char *osabi = NULL;
+
 public:
   target_desc ()
     : reg_defs (NULL), registers_size (0)
@@ -60,6 +66,15 @@ public:
     for (i = 0; VEC_iterate (tdesc_reg_p, reg_defs, i, reg); i++)
       xfree (reg);
     VEC_free (tdesc_reg_p, reg_defs);
+
+    xfree ((char *) arch);
+    xfree ((char *) osabi);
+
+    char *f;
+
+    for (i = 0; VEC_iterate (char_ptr, features, i, f); i++)
+      xfree (f);
+    VEC_free (char_ptr, features);
   }
   bool operator!= (const target_desc &other) const
   {
@@ -90,9 +105,6 @@ public:
     if (other.expedite_regs[i] != NULL)
       return true;
 
-    if (strcmp (xmltarget, other.xmltarget) != 0)
-      return true;
-
     return false;
   }
 
@@ -118,6 +130,11 @@ void init_target_desc (struct target_desc *tdesc);
 const struct target_desc *current_target_desc (void);
 
 #ifndef IN_PROCESS_AGENT
+void set_tdesc_architecture (struct target_desc *target_desc,
+			     const char *name);
+void set_tdesc_osabi (struct target_desc *target_desc, const char *name);
+
+const char *tdesc_get_features_xml (struct target_desc *tdesc);
 #endif
 
 #define tdesc_feature target_desc
@@ -125,7 +142,8 @@ const struct target_desc *current_target_desc (void);
 struct tdesc_type;
 
 struct tdesc_feature *tdesc_create_feature (struct target_desc *tdesc,
-					    const char *name);
+					    const char *name,
+					    const char *xml = NULL);
 
 struct tdesc_type *tdesc_create_flags (struct tdesc_feature *feature,
 				       const char *name, int size);
diff --git a/gdb/target-descriptions.c b/gdb/target-descriptions.c
index 1795518..2476082 100644
--- a/gdb/target-descriptions.c
+++ b/gdb/target-descriptions.c
@@ -1743,7 +1743,8 @@ tdesc_add_enum_value (struct tdesc_type *type, int value,
 }
 
 struct tdesc_feature *
-tdesc_create_feature (struct target_desc *tdesc, const char *name)
+tdesc_create_feature (struct target_desc *tdesc, const char *name,
+		      const char *xml)
 {
   struct tdesc_feature *new_feature = new tdesc_feature (name);
 
@@ -2192,8 +2193,10 @@ public:
 
     printf_unfiltered ("{\n");
     printf_unfiltered ("  struct tdesc_feature *feature;\n");
-    printf_unfiltered ("\n  feature = tdesc_create_feature (result, \"%s\");\n",
-		       e->name);
+
+    printf_unfiltered
+      ("\n  feature = tdesc_create_feature (result, \"%s\", \"%s\");\n",
+       e->name, lbasename (m_filename_after_features.c_str ()));
   }
 
   void visit_end (const tdesc_feature *e) override
diff --git a/gdb/target-descriptions.h b/gdb/target-descriptions.h
index d730672..25afaf0 100644
--- a/gdb/target-descriptions.h
+++ b/gdb/target-descriptions.h
@@ -222,7 +222,8 @@ void tdesc_add_compatible (struct target_desc *,
 			   const struct bfd_arch_info *);
 
 struct tdesc_feature *tdesc_create_feature (struct target_desc *tdesc,
-					    const char *name);
+					    const char *name,
+					    const char *xml = NULL);
 struct tdesc_type *tdesc_create_vector (struct tdesc_feature *feature,
 					const char *name,
 					struct tdesc_type *field_type,