Centralize amd64-linux target descriptions

This patch adds a new function amd64_linux_read_description, which
creates amd64-linux target descriptions according to its two
arguments, xcr0 and is_x32.

gdb:

2017-09-05  Yao Qi  <yao.qi@linaro.org>

	* amd64-linux-tdep.c (amd64_linux_read_description): New
	function.
	(amd64_linux_core_read_description): Call
	amd64_linux_read_description.
	(amd64_linux_init_abi): Likewise.
	(amd64_x32_linux_init_abi): Likewise.
	* amd64-linux-tdep.h (amd64_linux_read_description): Declare.
	* x86-linux-nat.c (x86_linux_read_description): Call
	amd64_linux_read_description.

1 files changed, 28 insertions, 18 deletions

diff --git a/gdb/amd64-linux-tdep.c b/gdb/amd64-linux-tdep.c
index 54c2eb9fdc..85efbefd12 100644
--- a/gdb/amd64-linux-tdep.c
+++ b/gdb/amd64-linux-tdep.c
@@ -1575,54 +1575,61 @@ amd64_linux_record_signal (struct gdbarch *gdbarch,
   return 0;
 }
 
-/* Get Linux/x86 target description from core dump.  */
-
-static const struct target_desc *
-amd64_linux_core_read_description (struct gdbarch *gdbarch,
-				  struct target_ops *target,
-				  bfd *abfd)
+const target_desc *
+amd64_linux_read_description (uint64_t xcr0_features_bit, bool is_x32)
 {
-  /* Linux/x86-64.  */
-  uint64_t xcr0 = i386_linux_core_read_xcr0 (abfd);
-
-  switch (xcr0 & X86_XSTATE_ALL_MASK)
+  switch (xcr0_features_bit)
     {
     case X86_XSTATE_AVX_MPX_AVX512_PKU_MASK:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	/* No MPX, PKU on x32, fallback to AVX-AVX512.  */
 	return tdesc_x32_avx_avx512_linux;
       else
 	return tdesc_amd64_avx_mpx_avx512_pku_linux;
     case X86_XSTATE_AVX_AVX512_MASK:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	return tdesc_x32_avx_avx512_linux;
       else
 	return tdesc_amd64_avx_avx512_linux;
     case X86_XSTATE_MPX_MASK:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	/* No MPX on x32, fallback to AVX.  */
 	return tdesc_x32_avx_linux;
       else
 	return tdesc_amd64_mpx_linux;
     case X86_XSTATE_AVX_MPX_MASK:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	/* No MPX on x32, fallback to AVX.  */
 	return tdesc_x32_avx_linux;
       else
 	return tdesc_amd64_avx_mpx_linux;
     case X86_XSTATE_AVX_MASK:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	return tdesc_x32_avx_linux;
       else
 	return tdesc_amd64_avx_linux;
     default:
-      if (gdbarch_ptr_bit (gdbarch) == 32)
+      if (is_x32)
 	return tdesc_x32_linux;
       else
 	return tdesc_amd64_linux;
     }
 }
 
+/* Get Linux/x86 target description from core dump.  */
+
+static const struct target_desc *
+amd64_linux_core_read_description (struct gdbarch *gdbarch,
+				  struct target_ops *target,
+				  bfd *abfd)
+{
+  /* Linux/x86-64.  */
+  uint64_t xcr0 = i386_linux_core_read_xcr0 (abfd);
+
+  return amd64_linux_read_description (xcr0 & X86_XSTATE_ALL_MASK,
+				       gdbarch_ptr_bit (gdbarch) == 32);
+}
+
 /* Similar to amd64_supply_fpregset, but use XSAVE extended state.  */
 
 static void
@@ -1873,7 +1880,8 @@ amd64_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
   tdep->sizeof_gregset = 27 * 8;
 
-  amd64_init_abi (info, gdbarch, tdesc_amd64_linux);
+  amd64_init_abi (info, gdbarch,
+		  amd64_linux_read_description (X86_XSTATE_SSE_MASK, false));
 
   const target_desc *tdesc = tdep->tdesc;
 
@@ -2086,7 +2094,9 @@ amd64_x32_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   tdep->gregset_num_regs = ARRAY_SIZE (amd64_linux_gregset_reg_offset);
   tdep->sizeof_gregset = 27 * 8;
 
-  amd64_x32_init_abi (info, gdbarch, tdesc_x32_linux);
+  amd64_x32_init_abi (info, gdbarch,
+		      amd64_linux_read_description (X86_XSTATE_SSE_MASK,
+						    true));
 
   /* Reserve a number for orig_rax.  */
   set_gdbarch_num_regs (gdbarch, AMD64_LINUX_NUM_REGS);