PC-relative TLS support

[Alan Modra <amodra at gmail dot com>]

Supporting TLS for -mpcrel turns out to be relatively simple, in part
due to deciding that !TARGET_TLS_MARKERS with -mpcrel is silly.  No
assembler that I know of supporting prefix insns lacks TLS marker
support.  Also, at some point powerpc gcc ought to remove
!TARGET_TLS_MARKERS generally and simplify all the occurrences of
IS_NOMARK_TLSGETADDR in rs6000.md rather than complicating them.

Mike, the rs6000_option_override_internal hunk is new compared to
the patch you had from me.

        * config/rs6000/predicates.md (unspec_tls): Allow const0_rtx for got
	element of unspec vec.
        * config/rs6000/rs6000.c (rs6000_option_override_internal): Disable
	-mpcrel if -mno-tls-markers.
	(rs6000_legitimize_tls_address): Support PC-relative TLS.
        * config/rs6000/rs6000.md (UNSPEC_TLSTLS_PCREL): New unspec.
	(tls_gd_pcrel, tls_ld_pcrel): New insns.
        (tls_dtprel, tls_tprel): Set attr prefixed when tls_size is not 16.
        (tls_got_tprel_pcrel, tls_tls_pcrel): New insns.

diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index fba87946ec7..4ea588e1027 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -995,9 +995,9 @@
   if (CONST_INT_P (op))
     return 1;
   if (XINT (op, 1) == UNSPEC_TLSGD)
-    return REG_P (XVECEXP (op, 0, 1));
+    return REG_P (XVECEXP (op, 0, 1)) || XVECEXP (op, 0, 1) == const0_rtx;
   if (XINT (op, 1) == UNSPEC_TLSLD)
-    return REG_P (XVECEXP (op, 0, 0));
+    return REG_P (XVECEXP (op, 0, 0)) || XVECEXP (op, 0, 0) == const0_rtx;
   return 0;
 })
 
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 6aca0ce5bf3..c04206ab139 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -4216,6 +4216,16 @@ rs6000_option_override_internal (bool global_init_p)
 			    | OPTION_MASK_PCREL_OPT);
     }
 
+  /* -mpcrel requires tls marker support.  */
+  if (TARGET_PCREL && !TARGET_TLS_MARKERS)
+    {
+      if ((rs6000_isa_flags_explicit & OPTION_MASK_PCREL) != 0)
+	error ("%qs requires %qs", "-mpcrel", "-mtls-markers");
+
+      rs6000_isa_flags &= ~(OPTION_MASK_PCREL
+			    | OPTION_MASK_PCREL_OPT);
+    }
+
   /* Check -mfuture debug switches.  */
   if (!TARGET_PCREL && TARGET_PCREL_OPT)
     {
@@ -8613,7 +8623,8 @@ rs6000_legitimize_tls_address (rtx addr, enum tls_model model)
     return rs6000_legitimize_tls_address_aix (addr, model);
 
   dest = gen_reg_rtx (Pmode);
-  if (model == TLS_MODEL_LOCAL_EXEC && rs6000_tls_size == 16)
+  if (model == TLS_MODEL_LOCAL_EXEC
+      && (rs6000_tls_size == 16 || rs6000_pcrel_p (cfun)))
     {
       rtx tlsreg;
 
@@ -8660,7 +8671,9 @@ rs6000_legitimize_tls_address (rtx addr, enum tls_model model)
 	 them in the .got section.  So use a pointer to the .got section,
 	 not one to secondary TOC sections used by 64-bit -mminimal-toc,
 	 or to secondary GOT sections used by 32-bit -fPIC.  */
-      if (TARGET_64BIT)
+      if (rs6000_pcrel_p (cfun))
+	got = const0_rtx;
+      else if (TARGET_64BIT)
 	got = gen_rtx_REG (Pmode, 2);
       else
 	{
@@ -8735,7 +8748,7 @@ rs6000_legitimize_tls_address (rtx addr, enum tls_model model)
 	  rtx uns = gen_rtx_UNSPEC (Pmode, vec, UNSPEC_TLS_GET_ADDR);
 	  set_unique_reg_note (get_last_insn (), REG_EQUAL, uns);
 
-	  if (rs6000_tls_size == 16)
+	  if (rs6000_tls_size == 16 || rs6000_pcrel_p (cfun))
 	    {
 	      if (TARGET_64BIT)
 		insn = gen_tls_dtprel_64 (dest, tmp1, addr);
@@ -8776,7 +8789,14 @@ rs6000_legitimize_tls_address (rtx addr, enum tls_model model)
 	  else
 	    insn = gen_tls_got_tprel_32 (tmp2, got, addr);
 	  emit_insn (insn);
-	  if (TARGET_64BIT)
+	  if (rs6000_pcrel_p (cfun))
+	    {
+	      if (TARGET_64BIT)
+		insn = gen_tls_tls_pcrel_64 (dest, tmp2, addr);
+	      else
+		insn = gen_tls_tls_pcrel_32 (dest, tmp2, addr);
+	    }
+	  else if (TARGET_64BIT)
 	    insn = gen_tls_tls_64 (dest, tmp2, addr);
 	  else
 	    insn = gen_tls_tls_32 (dest, tmp2, addr);
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 0e7d90e5357..6e32d8fdff1 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -88,6 +88,7 @@
    UNSPEC_TLSTPRELLO
    UNSPEC_TLSGOTTPREL
    UNSPEC_TLSTLS
+   UNSPEC_TLSTLS_PCREL
    UNSPEC_FIX_TRUNC_TF		; fadd, rounding towards zero
    UNSPEC_STFIWX
    UNSPEC_POPCNTB
@@ -9514,6 +9515,15 @@
 
 ;; TLS support.
 
+(define_insn "*tls_gd_pcrel<bits>"
+  [(set (match_operand:P 0 "gpc_reg_operand" "=b")
+	(unspec:P [(match_operand:P 1 "rs6000_tls_symbol_ref" "")
+		   (const_int 0)]
+		  UNSPEC_TLSGD))]
+  "HAVE_AS_TLS && TARGET_TLS_MARKERS"
+  "la %0,%1@got@tlsgd@pcrel"
+  [(set_attr "prefixed" "yes")])
+
 (define_insn_and_split "*tls_gd<bits>"
   [(set (match_operand:P 0 "gpc_reg_operand" "=b")
 	(unspec:P [(match_operand:P 1 "rs6000_tls_symbol_ref" "")
@@ -9554,6 +9564,14 @@
   "HAVE_AS_TLS && TARGET_TLS_MARKERS && TARGET_CMODEL != CMODEL_SMALL"
   "addi %0,%1,%2@got@tlsgd@l")
 
+(define_insn "*tls_ld_pcrel<bits>"
+  [(set (match_operand:P 0 "gpc_reg_operand" "=b")
+	(unspec:P [(const_int 0)]
+		  UNSPEC_TLSLD))]
+  "HAVE_AS_TLS && TARGET_TLS_MARKERS"
+  "la %0,%&@got@tlsld@pcrel"
+  [(set_attr "prefixed" "yes")])
+
 (define_insn_and_split "*tls_ld<bits>"
   [(set (match_operand:P 0 "gpc_reg_operand" "=b")
 	(unspec:P [(match_operand:P 1 "gpc_reg_operand" "b")]
@@ -9597,7 +9615,11 @@
 		   (match_operand:P 2 "rs6000_tls_symbol_ref" "")]
 		  UNSPEC_TLSDTPREL))]
   "HAVE_AS_TLS"
-  "addi %0,%1,%2@dtprel")
+  "addi %0,%1,%2@dtprel"
+  [(set (attr "prefixed")
+	(if_then_else (match_test "rs6000_tls_size == 16")
+		      (const_string "no")
+		      (const_string "yes")))])
 
 (define_insn "tls_dtprel_ha_<bits>"
   [(set (match_operand:P 0 "gpc_reg_operand" "=r")
@@ -9661,7 +9683,11 @@
 		   (match_operand:P 2 "rs6000_tls_symbol_ref" "")]
 		  UNSPEC_TLSTPREL))]
   "HAVE_AS_TLS"
-  "addi %0,%1,%2@tprel")
+  "addi %0,%1,%2@tprel"
+  [(set (attr "prefixed")
+	(if_then_else (match_test "rs6000_tls_size == 16")
+		      (const_string "no")
+		      (const_string "yes")))])
 
 (define_insn "tls_tprel_ha_<bits>"
   [(set (match_operand:P 0 "gpc_reg_operand" "=r")
@@ -9679,6 +9705,15 @@
   "HAVE_AS_TLS"
   "addi %0,%1,%2@tprel@l")
 
+(define_insn "*tls_got_tprel_pcrel_<bits>"
+  [(set (match_operand:P 0 "gpc_reg_operand" "=b")
+	(unspec:P [(const_int 0)
+		   (match_operand:P 1 "rs6000_tls_symbol_ref" "")]
+		  UNSPEC_TLSGOTTPREL))]
+  "HAVE_AS_TLS"
+  "<ptrload> %0,%1@got@tprel@pcrel"
+  [(set_attr "prefixed" "yes")])
+
 ;; "b" output constraint here and on tls_tls input to support linker tls
 ;; optimization.  The linker may edit the instructions emitted by a
 ;; tls_got_tprel/tls_tls pair to addis,addi.
@@ -9722,6 +9757,14 @@
   "HAVE_AS_TLS && TARGET_CMODEL != CMODEL_SMALL"
   "<ptrload> %0,%2@got@tprel@l(%1)")
 
+(define_insn "tls_tls_pcrel_<bits>"
+  [(set (match_operand:P 0 "gpc_reg_operand" "=r")
+	(unspec:P [(match_operand:P 1 "gpc_reg_operand" "b")
+		   (match_operand:P 2 "rs6000_tls_symbol_ref" "")]
+		  UNSPEC_TLSTLS_PCREL))]
+  "TARGET_ELF && HAVE_AS_TLS"
+  "add %0,%1,%2@tls@pcrel")
+
 (define_insn "tls_tls_<bits>"
   [(set (match_operand:P 0 "gpc_reg_operand" "=r")
 	(unspec:P [(match_operand:P 1 "gpc_reg_operand" "b")

-- 
Alan Modra
Australia Development Lab, IBM