After r16-4081-g966cdec2b2 which added folding of __builtin_assume_aligned,
forwprop would propagate pointers that lower alignment replacing ones with
greater alignment. This causes us to lose alignment information that
__builtin_assume_aligned provided to expand. Normally this just loses some
optimizations except in the s390 case where the alignment is specifically
checked and was for inlining of the atomics; without this patch an infininite
loop would happen.
Note this was previously broken for -Og before r16-4081-g966cdec2b2. This
fixes -Og case as forwprop is used instead of copyprop.
This moves the testcase for pr107389.c to torture to get a generic testcase.
pr107389.c was originally for -O0 case but we should test for other
optimization levels so this is not lost again.
align-5.c is xfailed because __builtin_assume_aligned is not instrumented for
ubsan
alignment and ubsan check to see pointer is aligned before emitting a check for
the
load (based on the known alignment in compiling). See PR 122038 too. I had
mentioned
this issue previously in r16-4081-g966cdec2b2 too.
PR middle-end/107389
PR tree-optimization/122086
gcc/ChangeLog:
* tree-ssa-forwprop.cc (forwprop_may_propagate_copy): New function.
(pass_forwprop::execute): Use forwprop_may_propagate_copy
instead of may_propagate_copy.
gcc/testsuite/ChangeLog:
* gcc.dg/pr107389.c: Move to...
* gcc.dg/torture/pr107389.c: ...here. Skip for lto.
Use dg-additional-options rather than dg-options.
* c-c++-common/ubsan/align-5.c: xfail.
Signed-off-by: Andrew Pinski <[email protected]>
---
gcc/testsuite/c-c++-common/ubsan/align-5.c | 4 ++-
gcc/testsuite/gcc.dg/{ => torture}/pr107389.c | 3 +-
gcc/tree-ssa-forwprop.cc | 32 ++++++++++++++++---
3 files changed, 33 insertions(+), 6 deletions(-)
rename gcc/testsuite/gcc.dg/{ => torture}/pr107389.c (73%)
diff --git a/gcc/testsuite/c-c++-common/ubsan/align-5.c
b/gcc/testsuite/c-c++-common/ubsan/align-5.c
index 484790134a6..6d2ac26612b 100644
--- a/gcc/testsuite/c-c++-common/ubsan/align-5.c
+++ b/gcc/testsuite/c-c++-common/ubsan/align-5.c
@@ -11,4 +11,6 @@ foo (char *p)
return *q;
}
-/* { dg-final { scan-assembler "__ubsan_handle" } } */
+/* xfail, see PR 122038 as __builtin_assume_aligned should be instrumented
instead
+ of only the load. */
+/* { dg-final { scan-assembler "__ubsan_handle" { xfail *-*-* } } } */
diff --git a/gcc/testsuite/gcc.dg/pr107389.c
b/gcc/testsuite/gcc.dg/torture/pr107389.c
similarity index 73%
rename from gcc/testsuite/gcc.dg/pr107389.c
rename to gcc/testsuite/gcc.dg/torture/pr107389.c
index deb63380704..23c2776ab73 100644
--- a/gcc/testsuite/gcc.dg/pr107389.c
+++ b/gcc/testsuite/gcc.dg/torture/pr107389.c
@@ -1,5 +1,6 @@
/* { dg-do compile } */
-/* { dg-options "-fdump-tree-optimized-alias" } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
+/* { dg-additional-options "-fdump-tree-optimized-alias" } */
unsigned foo (void *p)
{
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 68e80baa46c..98c98dd8be4 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -216,6 +216,30 @@ static bitmap to_purge;
/* Const-and-copy lattice. */
static vec<tree> lattice;
+/* forwprop_may_propagate_copy is like may_propagate_copy except
+ after the final folding, don't allow propagating of pointer ORIG
+ that have a lower alignment than the DEST name.
+ This is to prevent losing alignment information from __
builtin_assume_aligned for expand (See also PR 122086). */
+static bool
+forwprop_may_propagate_copy (tree dest, tree orig,
+ bool dest_not_abnormal_phi_edge_p = false)
+{
+ if (!may_propagate_copy (dest, orig, dest_not_abnormal_phi_edge_p))
+ return false;
+
+ /* Only check alignment for the final folding. */
+ if (!(cfun->curr_properties & PROP_last_full_fold))
+ return true;
+
+ /* Alignment only matters for pointer types. */
+ if (!POINTER_TYPE_P (TREE_TYPE (dest)) || !POINTER_TYPE_P (TREE_TYPE (orig)))
+ return true;
+
+ unsigned aligndest = get_pointer_alignment (dest);
+ unsigned alignorig = get_pointer_alignment (orig);
+ return aligndest <= alignorig;
+}
+
/* Set the lattice entry for NAME to VAL. */
static void
fwprop_set_lattice_val (tree name, tree val)
@@ -5177,7 +5201,7 @@ pass_forwprop::execute (function *fun)
}
if (all_same)
{
- if (may_propagate_copy (res, first))
+ if (forwprop_may_propagate_copy (res, first))
to_remove_defs.safe_push (SSA_NAME_VERSION (res));
fwprop_set_lattice_val (res, first);
}
@@ -5532,7 +5556,7 @@ pass_forwprop::execute (function *fun)
{
if (!is_gimple_debug (stmt))
bitmap_set_bit (simple_dce_worklist, SSA_NAME_VERSION
(use));
- if (may_propagate_copy (use, val))
+ if (forwprop_may_propagate_copy (use, val))
{
propagate_value (usep, val);
substituted_p = true;
@@ -5695,7 +5719,7 @@ pass_forwprop::execute (function *fun)
/* If we can propagate the lattice-value mark the
stmt for removal. */
if (val != lhs
- && may_propagate_copy (lhs, val))
+ && forwprop_may_propagate_copy (lhs, val))
to_remove_defs.safe_push (SSA_NAME_VERSION (lhs));
fwprop_set_lattice_val (lhs, val);
}
@@ -5717,7 +5741,7 @@ pass_forwprop::execute (function *fun)
continue;
tree val = fwprop_ssa_val (arg);
if (val != arg
- && may_propagate_copy (arg, val, !(e->flags & EDGE_ABNORMAL)))
+ && forwprop_may_propagate_copy (arg, val, !(e->flags &
EDGE_ABNORMAL)))
propagate_value (use_p, val);
}
--
2.43.0
