Refine constraint "Bk" to define_special_memory_constraint.

For below pattern, RA may still allocate r162 as v/k register, try to
reload for address with leaq __libc_tsd_CTYPE_B@gottpoff(%rip), %rsi
which result a linker error.

(set (reg:DI 162)
     (mem/u/c:DI
       (const:DI (unspec:DI
		 [(symbol_ref:DI ("a") [flags 0x60]  <var_decl 0x7f621f6e1c60 a>)]
		 UNSPEC_GOTNTPOFF))

Quote from H.J for why linker issue an error.
>What do these do:
>
>        leaq    __libc_tsd_CTYPE_B@gottpoff(%rip), %rax
>        vmovq   (%rax), %xmm0
>
>From x86-64 TLS psABI:
>
>The assembler generates for the x@gottpoff(%rip) expressions a R X86
>64 GOTTPOFF relocation for the symbol x which requests the linker to
>generate a GOT entry with a R X86 64 TPOFF64 relocation. The offset of
>the GOT entry relative to the end of the instruction is then used in
>the instruction. The R X86 64 TPOFF64 relocation is pro- cessed at
>program startup time by the dynamic linker by looking up the symbol x
>in the modules loaded at that point. The offset is written in the GOT
>entry and later loaded by the addq instruction.
>
>The above code sequence looks wrong to me.

gcc/ChangeLog:

	PR target/116043
	* config/i386/constraints.md (Bk): Refine to
	define_special_memory_constraint.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr116043.c: New test.

2 files changed, 34 insertions, 1 deletions

diff --git a/gcc/config/i386/constraints.md b/gcc/config/i386/constraints.md
index 7508d7a..b760e7c 100644
--- a/gcc/config/i386/constraints.md
+++ b/gcc/config/i386/constraints.md
@@ -187,7 +187,7 @@
   "@internal Vector memory operand."
   (match_operand 0 "vector_memory_operand"))
 
-(define_memory_constraint "Bk"
+(define_special_memory_constraint "Bk"
   "@internal TLS address that allows insn using non-integer registers."
   (and (match_operand 0 "memory_operand")
        (not (match_test "ix86_gpr_tls_address_pattern_p (op)"))))
diff --git a/gcc/testsuite/gcc.target/i386/pr116043.c b/gcc/testsuite/gcc.target/i386/pr116043.c
new file mode 100644
index 0000000..7655349
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr116043.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512bf16 -O3" } */
+/* { dg-final { scan-assembler-not {(?n)lea.*@gottpoff} } } */
+
+extern __thread int a, c, i, j, k, l;
+int *b;
+struct d {
+  int e;
+} f, g;
+char *h;
+
+void m(struct d *n) {
+  b = &k;
+  for (; n->e; b++, n--) {
+    i = b && a;
+    if (i)
+      j = c;
+  }
+}
+
+char *o(struct d *n) {
+  for (; n->e;)
+    return h;
+}
+
+int q() {
+  if (l)
+    return 1;
+  int p = *o(&g);
+  m(&f);
+  m(&g);
+  l = p;
+}