[PATCH] Fix PR70484, RTL DSE using wrong dependence check
Richard Biener
rguenther@suse.de
Fri Apr 1 09:08:00 GMT 2016
RTL DSE uses true_dependence to see whether a store may be killed by
anothe store - that's obviously broken. The following patch makes
it use output_dependence instead (introducing a canon_ variant of that).
Bootstrap & regtest running on x86_64-unknown-linux-gnu.
Ok?
Thanks,
Richard.
2016-04-01 Richard Biener <rguenther@suse.de>
PR rtl-optimization/70484
* rtl.h (canon_output_dependence): Declare.
* alias.c (canon_output_dependence): New function.
* dse.c (record_store): Use canon_output_dependence rather
than canon_true_dependence.
* gcc.dg/torture/pr70484.c: New testcase.
Index: gcc/rtl.h
===================================================================
*** gcc/rtl.h (revision 234663)
--- gcc/rtl.h (working copy)
*************** extern int anti_dependence (const_rtx, c
*** 3652,3657 ****
--- 3652,3659 ----
extern int canon_anti_dependence (const_rtx, bool,
const_rtx, machine_mode, rtx);
extern int output_dependence (const_rtx, const_rtx);
+ extern int canon_output_dependence (const_rtx, bool,
+ const_rtx, machine_mode, rtx);
extern int may_alias_p (const_rtx, const_rtx);
extern void init_alias_target (void);
extern void init_alias_analysis (void);
Index: gcc/alias.c
===================================================================
*** gcc/alias.c (revision 234663)
--- gcc/alias.c (working copy)
*************** output_dependence (const_rtx mem, const_
*** 3057,3062 ****
--- 3057,3076 ----
/*mem_canonicalized=*/false,
/*x_canonicalized*/false, /*writep=*/true);
}
+
+ /* Likewise, but we already have a canonicalized MEM, and X_ADDR for X.
+ Also, consider X in X_MODE (which might be from an enclosing
+ STRICT_LOW_PART / ZERO_EXTRACT).
+ If MEM_CANONICALIZED is true, MEM is canonicalized. */
+
+ int
+ canon_output_dependence (const_rtx mem, bool mem_canonicalized,
+ const_rtx x, machine_mode x_mode, rtx x_addr)
+ {
+ return write_dependence_p (mem, x, x_mode, x_addr,
+ mem_canonicalized, /*x_canonicalized=*/true,
+ /*writep=*/true);
+ }
Index: gcc/dse.c
===================================================================
*** gcc/dse.c (revision 234663)
--- gcc/dse.c (working copy)
*************** record_store (rtx body, bb_info_t bb_inf
*** 1609,1618 ****
the value of store_info. If it is, set the rhs to NULL to
keep it from being used to remove a load. */
{
! if (canon_true_dependence (s_info->mem,
! GET_MODE (s_info->mem),
! s_info->mem_addr,
! mem, mem_addr))
{
s_info->rhs = NULL;
s_info->const_rhs = NULL;
--- 1609,1617 ----
the value of store_info. If it is, set the rhs to NULL to
keep it from being used to remove a load. */
{
! if (canon_output_dependence (s_info->mem, true,
! mem, GET_MODE (mem),
! mem_addr))
{
s_info->rhs = NULL;
s_info->const_rhs = NULL;
Index: gcc/testsuite/gcc.dg/torture/pr70484.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr70484.c (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr70484.c (working copy)
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+
+extern void abort (void);
+
+int __attribute__((noinline,noclone))
+f(int *pi, long *pl)
+{
+ *pi = 1;
+ *pl = 0;
+ return *(char *)pi;
+}
+
+int main()
+{
+ char a[sizeof (long)];
+ if (f ((int *)a, (long *)a) != 0)
+ abort ();
+ return 0;
+}
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