[PATCH] -fopenmp-simd LTO ICE fix (PR middle-end/67452)

[Jakub Jelinek]

Hi!

This patch is a fix for gomp4.1 branch ICEs on
FAIL libgomp.c/for-5.c
FAIL libgomp.c++/for-13.C
that can be reproduced with intelmic emul offloading even on the trunk
with the attached testcase.  The problem is that LTO streaming doesn't
really like earlier unreferenced VAR_DECLs to be streamed late during
output_function (from output_cfg).

The patch fixes it by clearing loop->simduid when optimizations removed
all IL uses of the var and remove_unused_locals is about to nuke it from
cfun->local_decls.

Ok for trunk/5.3 if it passes bootstrap/regtest?

2015-09-04  Jakub Jelinek  <ja...@redhat.com>

        PR middle-end/67452
        * tree-ssa-live.c: Include cfgloop.h.
        (remove_unused_locals): Clear loop->simduid if simduid is about
        to be removed from cfun->local_decls.

        * gcc.dg/lto/pr67452_0.c: New test.

--- gcc/tree-ssa-live.c.jj      2015-08-24 18:27:19.738209359 +0200
+++ gcc/tree-ssa-live.c 2015-09-04 17:16:53.620321240 +0200
@@ -50,6 +50,7 @@ along with GCC; see the file COPYING3.
 #include "tree-ssa.h"
 #include "cgraph.h"
 #include "ipa-utils.h"
+#include "cfgloop.h"
 
 #ifdef ENABLE_CHECKING
 static void  verify_live_on_entry (tree_live_info_p);
@@ -820,6 +821,14 @@ remove_unused_locals (void)
          }
       }
 
+  if (cfun->has_simduid_loops)
+    {
+      struct loop *loop;
+      FOR_EACH_LOOP (loop, 0)
+       if (loop->simduid && !is_used_p (loop->simduid))
+         loop->simduid = NULL_TREE;
+    }
+
   cfun->has_local_explicit_reg_vars = false;
 
   /* Remove unmarked local and global vars from local_decls.  */
--- gcc/testsuite/gcc.dg/lto/pr67452_0.c.jj     2015-09-04 17:12:34.636045313 
+0200
+++ gcc/testsuite/gcc.dg/lto/pr67452_0.c        2015-09-04 17:13:18.473414952 
+0200
@@ -0,0 +1,23 @@
+/* { dg-lto-do link } */
+/* { dg-lto-options { { -O2 -flto -fopenmp-simd } } } */
+
+float b[3][3];
+
+__attribute__((used, noinline)) void
+foo ()
+{
+  int v1, v2;
+#pragma omp simd collapse(2)
+  for (v1 = 0; v1 < 3; v1++)
+    for (v2 = 0; v2 < 3; v2++)
+      b[v1][v2] = 2.5;
+}
+
+int
+main ()
+{
+  asm volatile ("" : : "g" (b) : "memory");
+  foo ();
+  asm volatile ("" : : "g" (b) : "memory");
+  return 0;
+}

        Jakub