LoongArch: Fix linker generate PLT entry for data symbol

With old "medium" code model, we call a function with a pair of PCALAU12I
and JIRL instructions. The assembler produces something like:

   8:	1a00000c 	pcalau12i   	$t0, 0
			8: R_LARCH_PCALA_HI20	g
   c:	4c000181 	jirl        	$ra, $t0, 0
			c: R_LARCH_PCALA_LO12	g

The linker generates a "PLT entry" for data without any diagnostic.
If "g" is a data symbol and ld with -shared option, it may load two
instructions in the PLT.

Without -shared option, loongarch_elf_adjust_dynamic_symbol can delete PLT
entry.

For R_LARCH_PCALA_HI20 relocation, linker only generate PLT entry for STT_FUNC
and STT_GNU_IFUNC symbols.

Author: cloudspurs

bfd/elfnn-loongarch.c

@@ -891,8 +891,12 @@ loongarch_elf_check_relocs (bfd *abfd, struct bfd_link_info *info,
 	    h->non_got_ref = 1;
 	  break;
 
+	/* For normal cmodel, pcalau12i + addi.d/w used to data.
+	   For first version medium cmodel, pcalau12i + jirl are used to
+	   function call, it need to creat PLT entry for STT_FUNC and
+	   STT_GNU_IFUNC type symbol.  */
 	case R_LARCH_PCALA_HI20:
-	  if (h != NULL)
+	  if (h != NULL && (STT_FUNC == h->type || STT_GNU_IFUNC == h->type))
 	    {
 	      /* For pcalau12i + jirl.  */
 	      h->needs_plt = 1;

ld/testsuite/ld-loongarch-elf/data-plt.s

@@ -0,0 +1,20 @@
+# The first version medium codel model function call is: pcalau12i + jirl.
+# R_LARCH_PCALA_HI20 only need to generate PLT entry for function symbols.
+	.text
+	.globl	a
+
+	.data
+	.align	2
+	.type	a, @object
+	.size	a, 4
+a:
+	.word	1
+
+	.text
+	.align	2
+	.globl	test
+	.type	test, @function
+test:
+	pcalau12i	$r12,%pc_hi20(a)
+	ld.w	$r12,$r12,%pc_lo12(a)
+	.size	test, .-test

ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp

@@ -59,6 +59,30 @@ if [istarget "loongarch64-*-*"] {
 	]
   }
 
+  # loongarch*-elf target do not support -shared option
+  if [check_shared_lib_support] {
+    run_ld_link_tests \
+	[list \
+	     [list \
+		  "data plt" \
+		  "-shared" "" \
+		  "" \
+		  {data-plt.s} \
+		  {} \
+		  "data-plt.so" \
+	     ] \
+	]
+
+    if [file exist "tmpdir/data-plt.so"] {
+      set objdump_output [run_host_cmd "objdump" "-d tmpdir/data-plt.so"]
+      if { [ regexp "<a@plt>" $objdump_output] } {
+	fail "data plt"
+      } {
+	pass "data plt"
+      }
+    }
+  }
+
   run_ld_link_tests \
       [list \
 	  [list \

ld/testsuite/ld-loongarch-elf/libjirl.s

@@ -1,2 +1,3 @@
+.type func @function
 pcalau12i $r12, %pc_hi20(func)
 jirl $r1,$r12, %pc_lo12(func)