Centralize i386 linux target descriptions

This patch moves all the tdesc_i386*_linux target descriptions to a
function i386_linux_read_description, which returns the right target
description according to xcr0.  This also remove the duplication in
getting target descriptions in corefile and native target.

gdb:

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

	* i386-linux-tdep.c (i386_linux_read_description): New function.
	(i386_linux_core_read_description): Call
	i386_linux_read_description.
	* i386-linux-tdep.h (i386_linux_read_description): Declare.
	(tdesc_i386_linux, tdesc_i386_mmx_linux): Remove declarations.
	(tdesc_i386_avx_linux, tdesc_i386_mpx_linux): Likewise
	(tdesc_i386_avx_mpx_linux, tdesc_i386_avx_avx512_linux): Likewise.
	(tdesc_i386_avx_mpx_avx512_pku_linux): Likewise.
	* x86-linux-nat.c (x86_linux_read_description): Call
	i386_linux_read_description.

1 files changed, 8 insertions, 16 deletions

diff --git a/gdb/x86-linux-nat.c b/gdb/x86-linux-nat.c
index 7362282..2c4afb1 100644
--- a/gdb/x86-linux-nat.c
+++ b/gdb/x86-linux-nat.c
@@ -153,7 +153,7 @@ x86_linux_read_description (struct target_ops *ops)
 	{
 	  have_ptrace_getfpxregs = 0;
 	  have_ptrace_getregset = TRIBOOL_FALSE;
-	  return tdesc_i386_mmx_linux;
+	  return i386_linux_read_description (X86_XSTATE_X87_MASK);
 	}
     }
 #endif
@@ -230,21 +230,13 @@ x86_linux_read_description (struct target_ops *ops)
     }
   else
     {
-      switch (xcr0_features_bits)
-	{
-	case X86_XSTATE_AVX_MPX_AVX512_PKU_MASK:
-	  return tdesc_i386_avx_mpx_avx512_pku_linux;
-	case X86_XSTATE_AVX_AVX512_MASK:
-	  return tdesc_i386_avx_avx512_linux;
-	case X86_XSTATE_MPX_MASK:
-	  return tdesc_i386_mpx_linux;
-	case X86_XSTATE_AVX_MPX_MASK:
-	  return tdesc_i386_avx_mpx_linux;
-	case X86_XSTATE_AVX_MASK:
-	  return tdesc_i386_avx_linux;
-	default:
-	  return tdesc_i386_linux;
-	}
+      const struct target_desc * tdesc
+	= i386_linux_read_description (xcr0_features_bits);
+
+      if (tdesc == NULL)
+	tdesc = i386_linux_read_description (X86_XSTATE_SSE_MASK);
+
+      return tdesc;
     }
 
   gdb_assert_not_reached ("failed to return tdesc");