[commit] SPU i-cache: Fix linker hang with cycles in CFG

[Ulrich Weigand]

Hello,

if a function is split up into sections, cycles in the control flow
graph may lead to cycles in the set of non-function-call branches
between sections.  If this happens, the SPU linker will sometimes
construct cycles in the struct function_info "start" linkage.
This in turn leads to an endless loop in the transfer_calls routine.
The following patch fixes this by never generating such cycles.

Tested on spu-elf with no regressions.
Approved off-line by Alan Modra; committed to mainline.

Bye,
Ulrich

ChangeLog:

	* elf32-spu.c (mark_functions_via_relocs): Handle cycles in the
	control flow graph between fragments of a function.

diff -urNp src.orig/bfd/elf32-spu.c src/bfd/elf32-spu.c
--- src.orig/bfd/elf32-spu.c	2009-05-11 16:11:11.000000000 +0200
+++ src/bfd/elf32-spu.c	2009-05-11 16:11:21.000000000 +0200
@@ -2779,7 +2779,14 @@ mark_functions_via_relocs (asection *sec
 	      callee->fun->is_func = TRUE;
 	    }
 	  else if (callee->fun->start == NULL)
-	    callee->fun->start = caller;
+	    {
+	      struct function_info *caller_start = caller;
+	      while (caller_start->start)
+		caller_start = caller_start->start;
+
+	      if (caller_start != callee->fun)
+		callee->fun->start = caller_start;
+	    }
 	  else
 	    {
 	      struct function_info *callee_start;
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com