PR rtl-optimization/70574

	* fwprop.c (forward_propagate_and_simplify): Don't add
	REG_EQUAL note if DF_REF_REG (use) is a paradoxical subreg.
	(try_fwprop_subst): Don't add REG_EQUAL note if there are any
	paradoxical subregs within *loc.

	* gcc.target/i386/avx2-pr70574.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@234833 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 15e3d22d535bc307a7517b0505c3b260a4f5322a..b9b36de74a505a06d2a5398196bea55bcf7905ab 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2016-04-08  Jakub Jelinek  <jakub@redhat.com>
+
+       PR rtl-optimization/70574
+       * fwprop.c (forward_propagate_and_simplify): Don't add
+       REG_EQUAL note if DF_REF_REG (use) is a paradoxical subreg.
+       (try_fwprop_subst): Don't add REG_EQUAL note if there are any
+       paradoxical subregs within *loc.
+
 2016-04-08  Thomas Schwinge  <thomas@codesourcery.com>
 
        * config/arc/arc.h (LINK_COMMAND_SPEC): Use gt to ignore

diff --git a/gcc/fwprop.c b/gcc/fwprop.c
index c4587d7bf7717c2acbf34cfeac5a73cfd489f6a2..d8cb9fa3bbb911f34eaa09b113c1481d4c71f6a2 100644 (file)
--- a/gcc/fwprop.c
+++ b/gcc/fwprop.c
@@ -999,10 +999,27 @@ try_fwprop_subst (df_ref use, rtx *loc, rtx new_rtx, rtx_insn *def_insn,
         making a new one if one does not already exist.  */
       if (set_reg_equal)
        {
-         if (dump_file)
-           fprintf (dump_file, " Setting REG_EQUAL note\n");
+         /* If there are any paradoxical SUBREGs, don't add REG_EQUAL note,
+            because the bits in there can be anything and so might not
+            match the REG_EQUAL note content.  See PR70574.  */
+         subrtx_var_iterator::array_type array;
+         FOR_EACH_SUBRTX_VAR (iter, array, *loc, NONCONST)
+           {
+             rtx x = *iter;
+             if (SUBREG_P (x) && paradoxical_subreg_p (x))
+               {
+                 set_reg_equal = false;
+                 break;
+               }
+           }
 
-         note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (new_rtx));
+         if (set_reg_equal)
+           {
+             if (dump_file)
+               fprintf (dump_file, " Setting REG_EQUAL note\n");
+
+             note = set_unique_reg_note (insn, REG_EQUAL, copy_rtx (new_rtx));
+           }
        }
     }
 
@@ -1300,14 +1317,19 @@ forward_propagate_and_simplify (df_ref use, rtx_insn *def_insn, rtx def_set)
         that isn't mentioned in USE_SET, as the note would be invalid
         otherwise.  We also don't want to install a note if we are merely
         propagating a pseudo since verifying that this pseudo isn't dead
-        is a pain; moreover such a note won't help anything.  */
+        is a pain; moreover such a note won't help anything.
+        If the use is a paradoxical subreg, make sure we don't add a
+        REG_EQUAL note for it, because it is not equivalent, it is one
+        possible value for it, but we can't rely on it holding that value.
+        See PR70574.  */
       set_reg_equal = (note == NULL_RTX
                       && REG_P (SET_DEST (use_set))
                       && !REG_P (src)
                       && !(GET_CODE (src) == SUBREG
                            && REG_P (SUBREG_REG (src)))
                       && !reg_mentioned_p (SET_DEST (use_set),
-                                           SET_SRC (use_set)));
+                                           SET_SRC (use_set))
+                      && !paradoxical_subreg_p (DF_REF_REG (use)));
     }
 
   if (GET_MODE (*loc) == VOIDmode)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 65c35e0c0918b9aca9cecb43c687286b37814b2b..e1f87b396f17f94f7a4f8eb8e5a93bb175e3cf39 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2016-04-08  Jakub Jelinek  <jakub@redhat.com>
+
+       PR rtl-optimization/70574
+       * gcc.target/i386/avx2-pr70574.c: New test.
+
 2016-04-08  Maxim Ostapenko  <m.ostapenko@samsung.com>
 
        PR sanitizer/70541

diff --git a/gcc/testsuite/gcc.target/i386/avx2-pr70574.c b/gcc/testsuite/gcc.target/i386/avx2-pr70574.c
new file mode 100644 (file)
index 0000000..c9867dd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx2-pr70574.c
@@ -0,0 +1,26 @@
+/* PR rtl-optimization/70574 */
+/* { dg-do run { target lp64 } } */
+/* { dg-require-effective-target avx2 } */
+/* { dg-options "-O -frerun-cse-after-loop -fno-tree-ccp -mcmodel=medium -mavx2" } */
+/* { dg-additional-options "-fPIC" { target fpic } } */
+
+#include "avx2-check.h"
+
+typedef char A __attribute__((vector_size (32)));
+typedef short B __attribute__((vector_size (32)));
+
+int
+foo (int x, __int128 y, __int128 z, A w)
+{
+  y <<= 64;
+  w *= (A) { 0, -1, z, 0, ~y };
+  return w[0] + ((B) { x, 0, y, 0, -1 } | 1)[4];
+}
+
+static void
+avx2_test ()
+{
+  int x = foo (0, 0, 0, (A) {});
+  if (x != -1)
+    __builtin_abort ();
+}