diff mbox

[ptx] overrride anchor hook

Message ID 564F2EC0.5060109@acm.org
State New
Headers show

Commit Message

Nathan Sidwell Nov. 20, 2015, 2:31 p.m. UTC 
Jim discovered that he needed to override the anchoring hook when using a PPC 
host-side compiler, but didn't figure out why this was needed.  Digging into it, 
I discovered that flag_section_anchors is cleared in toplev.c by the command 
line option machinery, if there are no anchor target hooks.  However, that's 
done in the host compiler and the LTO machinery simply copies the value over 
into the LTO compiler.   Usually that's fine, as the LTO compiler's for the same 
target architecture.  Except when it's an offload compiler.  The flags are not 
resanitized (perhaps that should be done?)

Anyway, that led to the PTX accelerator compiler trying to do section anchory 
things.  Fixed by overriding TARGET_USE_ANCHORS_FOR_SYMBOL_P to say 'no'.

I guess at the next instance of an offload compiler seeing a 'surprising' 
combination of optimization flags, we'll need a resanitize hook?  Jakub?

nathan
diff mbox

Patch

2015-11-20  Nathan Sidwell  <nathan@codesourcery.com>
	    James Norris  <jnorris@codesourcery.com>

	* config/nvptx/nvptx.c (nvptx_use_anchors_for_symbol_p): New.
	(TARGET_USE_ANCHORS_FOR_SYMBOL_P): Override.

Index: config/nvptx/nvptx.c
===================================================================
--- config/nvptx/nvptx.c	(revision 230657)
+++ config/nvptx/nvptx.c	(working copy)
@@ -3895,6 +3895,19 @@  nvptx_cannot_copy_insn_p (rtx_insn *insn
       return false;
     }
 }
+
+/* Section anchors do not work.  Initialization for flag_section_anchor
+   probes the existence of the anchoring target hooks and prevents
+   anchoring if they don't exist.  However, we may be being used with
+   a host-side compiler that does support anchoring, and hence see
+   the anchor flag set (as it's not recalculated).  So provide an
+   implementation denying anchoring.  */
+
+static bool
+nvptx_use_anchors_for_symbol_p (const_rtx ARG_UNUSED (a))
+{
+  return false;
+}
 
 /* Record a symbol for mkoffload to enter into the mapping table.  */
 
@@ -4914,6 +4927,9 @@  nvptx_goacc_reduction (gcall *call)
 #undef TARGET_CANNOT_COPY_INSN_P
 #define TARGET_CANNOT_COPY_INSN_P nvptx_cannot_copy_insn_p
 
+#undef TARGET_USE_ANCHORS_FOR_SYMBOL_P
+#define TARGET_USE_ANCHORS_FOR_SYMBOL_P nvptx_use_anchors_for_symbol_p
+
 #undef TARGET_INIT_BUILTINS
 #define TARGET_INIT_BUILTINS nvptx_init_builtins
 #undef TARGET_EXPAND_BUILTIN