Fix MIPS NewABI fallout from recent tree-nested.c fix

[Richard Sandiford]

Eric's recent tree-nested.c patch allows us to inline gcc.dg/nest.c:foo
into main.  This creates a function in which the only use of the $gp
register is an implicit one in FUNCTION_PROFILER, and a bug in the
MIPS port meant that we'd delete the initialisation as dead.

Fixed by extending the !TARGET_EXPLICIT_RELOCS case to include
crtl->profile as well, and making sure that it is used even
for LOADGP_ABSOLUTE (for which !TARGET_EXPLICIT_RELOCS is known
to be false).

Tested on mips64el-linux-gnu and applied.

Richard


gcc/
	* config/mips/mips.c (mips_emit_loadgp): Return early if
	there is nothing do to, otherwise emit a blockage if
	!TARGET_EXPLICIT_RELOCS || crtl->profile.
	* config/mips/mips.md (loadgp_blockage): Use SI rather than DI.

Index: gcc/config/mips/mips.c
===================================================================
--- gcc/config/mips/mips.c	2008-06-02 22:08:27.000000000 +0100
+++ gcc/config/mips/mips.c	2008-06-02 22:08:28.000000000 +0100
@@ -8538,8 +8538,6 @@ mips_emit_loadgp (void)
       emit_insn (Pmode == SImode
 		 ? gen_loadgp_newabi_si (pic_reg, offset, incoming_address)
 		 : gen_loadgp_newabi_di (pic_reg, offset, incoming_address));
-      if (!TARGET_EXPLICIT_RELOCS)
-	emit_insn (gen_loadgp_blockage ());
       break;
 
     case LOADGP_RTP:
@@ -8548,13 +8546,16 @@ mips_emit_loadgp (void)
       emit_insn (Pmode == SImode
 		 ? gen_loadgp_rtp_si (pic_reg, base, index)
 		 : gen_loadgp_rtp_di (pic_reg, base, index));
-      if (!TARGET_EXPLICIT_RELOCS)
-	emit_insn (gen_loadgp_blockage ());
       break;
 
     default:
-      break;
+      return;
     }
+  /* Emit a blockage if there are implicit uses of the GP register.
+     This includes profiled functions, because FUNCTION_PROFILE uses
+     a jal macro.  */
+  if (!TARGET_EXPLICIT_RELOCS || crtl->profile)
+    emit_insn (gen_loadgp_blockage ());
 }
 
 /* Expand the "prologue" pattern.  */
Index: gcc/config/mips/mips.md
===================================================================
--- gcc/config/mips/mips.md	2008-06-02 22:08:27.000000000 +0100
+++ gcc/config/mips/mips.md	2008-06-02 22:08:28.000000000 +0100
@@ -4367,12 +4367,11 @@ (define_insn_and_split "loadgp_absolute_
 }
   [(set_attr "length" "8")])
 
-;; The use of gp is hidden when not using explicit relocations.
 ;; This blockage instruction prevents the gp load from being
 ;; scheduled after an implicit use of gp.  It also prevents
 ;; the load from being deleted as dead.
 (define_insn "loadgp_blockage"
-  [(unspec_volatile [(reg:DI 28)] UNSPEC_BLOCKAGE)]
+  [(unspec_volatile [(reg:SI 28)] UNSPEC_BLOCKAGE)]
   ""
   ""
   [(set_attr "type" "ghost")