[Patch] lto-wrapper.c: Use -flto-partition=none with offloading (PR97179)

[Tobias Burnus <tobias@codesourcery.com>]

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(Pre-remark: the following applies to the host; the offloading
is only involved as otherwise the (.gnu.)offload_{vars,funcs}
global variable/table wouldn't exist.)

Due to partitioning, it can happen that the offloading table
and the functions and variables (which it contains as pointer),
end up in different ltrans.  As the functions and vars end
up as local symbols – the linker will not associate the entries
in the table of one ltrans with the symbol from the other ltrans,
failing with "undefined reference" errors.


This could be fixed properly by either placing all vars/funcs
referenced in the (.gnu.)offload_{vars,funcs} table in the same
ltrans parition — or by ensuring that those symbols are available.
For funcs, the latter works by setting TREE_PUBLIC (cf. PR) – but
I didn't manage to do this for variables. — Hence:

This patch disables lto partitioning if the code has offloading.

OK for mainline? — Or better suggestions how to handle this?

Tobias

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lto-wrapper.c: Use -flto-partition=none with offloading (PR97179)

gcc/ChangeLog:

	PR lto/97179
	* lto-wrapper.c (run_gcc):

diff --git a/gcc/lto-wrapper.c b/gcc/lto-wrapper.c
index 82cfa6bd67e..027db8c5200 100644
--- a/gcc/lto-wrapper.c
+++ b/gcc/lto-wrapper.c
@@ -1490,6 +1490,12 @@ run_gcc (unsigned argc, char *argv[])
 	case OPT_flto_partition_:
 	  if (strcmp (option->arg, "none") == 0)
 	    no_partition = true;
+	  else if (have_offload)
+	    {
+	      /* PR lto/97179.  */
+	      no_partition = true;
+	      warning (0, "Ignoring %<-flto_partition%> as offloading is used");
+	    }
 	  break;
 
 	case OPT_flto_: