tree-optimization/110799 - fix bug in code hoisting
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Commit Message
Code hoisting part of GIMPLE PRE failed to adjust the TBAA behavior
of common loads in the case the alias set of the ref was the same
but the base alias set was not. It also failed to adjust the
base behavior, assuming it would match. The following plugs this
hole.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/110799
* tree-ssa-pre.cc (compute_avail): More thoroughly match
up TBAA behavior of redundant loads.
* gcc.dg/torture/pr110799.c: New testcase.
---
gcc/testsuite/gcc.dg/torture/pr110799.c | 46 +++++++++++++++++++++++++
gcc/tree-ssa-pre.cc | 15 +++++---
2 files changed, 56 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr110799.c
new file mode 100644
@@ -0,0 +1,46 @@
+/* { dg-do run { target { { *-*-linux* *-*-gnu* *-*-uclinux* } && mmap } } } */
+
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+struct S {
+ int a;
+};
+struct M {
+ int a, b;
+};
+
+int __attribute__((noipa))
+f(struct S *p, int c, int d)
+{
+ int r;
+ if (c)
+ {
+ if (d)
+ r = p->a;
+ else
+ r = ((struct M*)p)->a;
+ }
+ else
+ r = ((struct M*)p)->b;
+ return r;
+}
+
+int main ()
+{
+ long pgsz = sysconf(_SC_PAGESIZE);
+ if (pgsz < sizeof (struct M))
+ return 0;
+ char *p = mmap ((void *) 0, 2 * pgsz, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS,
+ -1, 0);
+ if (p == MAP_FAILED)
+ return 0;
+ if (mprotect (p, pgsz, PROT_READ | PROT_WRITE))
+ return 0;
+ struct S *q = (struct S *)(p + pgsz) - 1;
+ q->a = 42;
+ if (f (q, 1, 1) != 42)
+ abort ();
+ return 0;
+}
@@ -4217,8 +4217,10 @@ compute_avail (function *fun)
/* TBAA behavior is an obvious part so make sure
that the hashtable one covers this as well
by adjusting the ref alias set and its base. */
- if (ref->set == set
- || alias_set_subset_of (set, ref->set))
+ if ((ref->set == set
+ || alias_set_subset_of (set, ref->set))
+ && (ref->base_set == base_set
+ || alias_set_subset_of (base_set, ref->base_set)))
;
else if (ref1->opcode != ref2->opcode
|| (ref1->opcode != MEM_REF
@@ -4230,16 +4232,19 @@ compute_avail (function *fun)
operands.release ();
continue;
}
- else if (alias_set_subset_of (ref->set, set))
+ else if (ref->set == set
+ || alias_set_subset_of (ref->set, set))
{
+ tree reft = reference_alias_ptr_type (rhs1);
ref->set = set;
+ ref->base_set = set;
if (ref1->opcode == MEM_REF)
ref1->op0
- = wide_int_to_tree (TREE_TYPE (ref2->op0),
+ = wide_int_to_tree (reft,
wi::to_wide (ref1->op0));
else
ref1->op2
- = wide_int_to_tree (TREE_TYPE (ref2->op2),
+ = wide_int_to_tree (reft,
wi::to_wide (ref1->op2));
}
else