Re: RFA: Fix rtl-optimization/57425

[Joern Rennecke <joern dot rennecke at embecosm dot com>]

Quoting Eric Botcazou <ebotcazou@adacore.com>:

> Could you also check that your patch also fixes PR opt/57569 and, if so, add
> the reference to the ChangeLog as well as the testcase?

Attached is what I'm currently testing. bootstrap on i686-pc-linux-gnu
finished, now regtesting.
On x86_64-pc-linux-gnu, bootstrap is still in progress & I also still have
to verify if the pr57569.c testcase FAILs/PASSes for unpatched/patched
svn trunk.

2013-06-15  Joern Rennecke <joern.rennecke@embecosm.com>

gcc:
	PR rtl-optimization/57425
	PR rtl-optimization/57569
	* alias.c (write_dependence_p): Add new parameters mem_size,
	canon_mem_addr and mem_canonicalized.  Change type of writep to bool.
	Changed all callers.
	(canon_anti_dependence): New function.
	* cse.c (check_dependence): Use canon_anti_dependence.
	* cselib.c (cselib_invalidate_mem): Likewise.
	* rtl.h (canon_anti_dependence): Declare.
gcc/testsuite:
	PR rtl-optimization/57425
	PR rtl-optimization/57569
	* gcc.dg/torture/pr57425-1.c, gcc.dg/torture/pr57425-2.c: New files.
	* gcc.dg/torture/pr57425-3.c, gcc.dg/torture/pr57569.c: Likewise.

Index: alias.c
===================================================================
--- alias.c	(revision 200126)
+++ alias.c	(working copy)
@@ -156,7 +156,8 @@ static int insert_subset_children (splay
 static alias_set_entry get_alias_set_entry (alias_set_type);
 static bool nonoverlapping_component_refs_p (const_rtx, const_rtx);
 static tree decl_for_component_ref (tree);
-static int write_dependence_p (const_rtx, const_rtx, int);
+static int write_dependence_p (const_rtx, enum machine_mode, rtx, const_rtx,
+			       bool, bool);
 
 static void memory_modified_1 (rtx, const_rtx, void *);
 
@@ -2553,15 +2554,22 @@ canon_true_dependence (const_rtx mem, en
 }
 
 /* Returns nonzero if a write to X might alias a previous read from
-   (or, if WRITEP is nonzero, a write to) MEM.  */
+   (or, if WRITEP is true, a write to) MEM.
+   If MEM_CANONCALIZED is nonzero, CANON_MEM_ADDR is the canonicalized
+   address of MEM, and MEM_MODE the mode for that access.  */
 
 static int
-write_dependence_p (const_rtx mem, const_rtx x, int writep)
+write_dependence_p (const_rtx mem, enum machine_mode mem_mode,
+		    rtx canon_mem_addr, const_rtx x,
+		    bool mem_canonicalized, bool writep)
 {
   rtx x_addr, mem_addr;
   rtx base;
   int ret;
 
+  gcc_checking_assert (mem_canonicalized ? (canon_mem_addr != NULL_RTX)
+		       : (canon_mem_addr == NULL_RTX && mem_mode == VOIDmode));
+
   if (MEM_VOLATILE_P (x) && MEM_VOLATILE_P (mem))
     return 1;
 
@@ -2612,9 +2620,15 @@ write_dependence_p (const_rtx mem, const
     return 0;
 
   x_addr = canon_rtx (x_addr);
-  mem_addr = canon_rtx (mem_addr);
+  if (mem_canonicalized)
+    mem_addr = canon_mem_addr;
+  else
+    {
+      mem_addr = canon_rtx (mem_addr);
+      mem_mode = GET_MODE (mem);
+    }
 
-  if ((ret = memrefs_conflict_p (SIZE_FOR_MODE (mem), mem_addr,
+  if ((ret = memrefs_conflict_p (GET_MODE_SIZE (mem_mode), mem_addr,
 				 SIZE_FOR_MODE (x), x_addr, 0)) != -1)
     return ret;
 
@@ -2629,7 +2643,20 @@ write_dependence_p (const_rtx mem, const
 int
 anti_dependence (const_rtx mem, const_rtx x)
 {
-  return write_dependence_p (mem, x, /*writep=*/0);
+  return write_dependence_p (mem, VOIDmode, NULL_RTX, x,
+			     /*mem_canonicalized=*/false, /*writep=*/false);
+}
+
+/* Likewise, but we already have a canonicalized MEM_ADDR for MEM.
+   Also, consider MEM in MEM_MODE (which might be from an enclosing
+   STRICT_LOW_PART / ZERO_EXTRACT).  */
+
+int
+canon_anti_dependence (const_rtx mem, enum machine_mode mem_mode,
+		       rtx mem_addr, const_rtx x)
+{
+  return write_dependence_p (mem, mem_mode, mem_addr, x,
+			     /*mem_canonicalized=*/true, /*writep=*/false);
 }
 
 /* Output dependence: X is written after store in MEM takes place.  */
@@ -2637,7 +2664,8 @@ anti_dependence (const_rtx mem, const_rt
 int
 output_dependence (const_rtx mem, const_rtx x)
 {
-  return write_dependence_p (mem, x, /*writep=*/1);
+  return write_dependence_p (mem, VOIDmode, NULL_RTX, x,
+			     /*mem_canonicalized=*/false, /*writep=*/true);
 }
 
 
Index: cse.c
===================================================================
--- cse.c	(revision 200126)
+++ cse.c	(working copy)
@@ -1824,7 +1824,7 @@ flush_hash_table (void)
       }
 }
 
-/* Function called for each rtx to check whether true dependence exist.  */
+/* Function called for each rtx to check whether an anti dependence exist.  */
 struct check_dependence_data
 {
   enum machine_mode mode;
@@ -1837,7 +1837,7 @@ check_dependence (rtx *x, void *data)
 {
   struct check_dependence_data *d = (struct check_dependence_data *) data;
   if (*x && MEM_P (*x))
-    return canon_true_dependence (d->exp, d->mode, d->addr, *x, NULL_RTX);
+    return canon_anti_dependence (d->exp, d->mode, d->addr, *x);
   else
     return 0;
 }
Index: cselib.c
===================================================================
--- cselib.c	(revision 200126)
+++ cselib.c	(working copy)
@@ -2263,8 +2263,8 @@ cselib_invalidate_mem (rtx mem_rtx)
 	      continue;
 	    }
 	  if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
-	      && ! canon_true_dependence (mem_rtx, GET_MODE (mem_rtx),
-					  mem_addr, x, NULL_RTX))
+	      && ! canon_anti_dependence (mem_rtx, GET_MODE (mem_rtx),
+					  mem_addr, x))
 	    {
 	      has_mem = true;
 	      num_mems++;
Index: rtl.h
===================================================================
--- rtl.h	(revision 200126)
+++ rtl.h	(working copy)
@@ -2705,6 +2705,8 @@ extern int canon_true_dependence (const_
 				  const_rtx, rtx);
 extern int read_dependence (const_rtx, const_rtx);
 extern int anti_dependence (const_rtx, const_rtx);
+extern int canon_anti_dependence (const_rtx, enum machine_mode, rtx,
+				  const_rtx);
 extern int output_dependence (const_rtx, const_rtx);
 extern int may_alias_p (const_rtx, const_rtx);
 extern void init_alias_target (void);
Index: testsuite/gcc.dg/torture/pr57425-1.c
===================================================================
--- testsuite/gcc.dg/torture/pr57425-1.c	(revision 0)
+++ testsuite/gcc.dg/torture/pr57425-1.c	(working copy)
@@ -0,0 +1,37 @@
+/* { dg-do run } */
+
+extern void abort (void) __attribute__((noreturn));
+
+union setconflict
+{
+  int a[20];
+  long b[10];
+};
+
+int
+main ()
+{
+  int sum = 0;
+  {
+    union setconflict a;
+    int *c;
+    c = a.a;
+    asm ("": "=r" (c):"0" (c));
+    *c = 0;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+  {
+    union setconflict a;
+    long *c;
+    c = a.b;
+    asm ("": "=r" (c):"0" (c));
+    *c = 1;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+
+  if (sum != 1)
+    abort();
+  return 0;
+}
Index: testsuite/gcc.dg/torture/pr57425-2.c
===================================================================
--- testsuite/gcc.dg/torture/pr57425-2.c	(revision 0)
+++ testsuite/gcc.dg/torture/pr57425-2.c	(working copy)
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+
+extern void abort (void) __attribute__((noreturn));
+
+int
+main ()
+{
+  int sum = 0;
+  {
+    int a[20];
+    int *c;
+    c = a;
+    asm ("": "=r" (c):"0" (c));
+    *c = 0;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+  {
+    long b[10];
+    long *c;
+    c = b;
+    asm ("": "=r" (c):"0" (c));
+    *c = 1;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+
+  if (sum != 1)
+    abort();
+  return 0;
+}
Index: testsuite/gcc.dg/torture/pr57425-3.c
===================================================================
--- testsuite/gcc.dg/torture/pr57425-3.c	(revision 0)
+++ testsuite/gcc.dg/torture/pr57425-3.c	(working copy)
@@ -0,0 +1,31 @@
+/* { dg-do run } */
+
+extern void abort (void) __attribute__((noreturn));
+
+int
+main ()
+{
+  int sum = 0;
+  {
+    long a[20];
+    long *c;
+    c = a;
+    asm ("": "=r" (c):"0" (c));
+    *c = 0;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+  {
+    long long b[10];
+    long long *c;
+    c = b;
+    asm ("": "=r" (c):"0" (c));
+    *c = 1;
+    asm ("": "=r" (c):"0" (c));
+    sum += *c;
+  }
+
+  if (sum != 1)
+    abort();
+  return 0;
+}
Index: testsuite/gcc.dg/torture/pr57569.c
===================================================================
--- testsuite/gcc.dg/torture/pr57569.c	(revision 0)
+++ testsuite/gcc.dg/torture/pr57569.c	(working copy)
@@ -0,0 +1,37 @@
+/* { dg-do run } */
+
+extern void abort (void) __attribute__((noreturn));
+
+struct S { int f0; } a; 
+
+int b, e, *d = &b, f;
+
+void 
+fn1 ()
+{
+  int **g[9][6];
+  int ***h = &g[6][3];
+  for (; e < 9; e++) {
+    f = 0;
+    for (; f < 6; f++)
+      g[e][f] = &d;
+  }
+  ***h = 0;
+}
+
+void
+fn2 ()
+{
+  fn1 ();
+  struct S c[4][10] = {};
+  a = c[3][9];
+}
+
+int
+main ()
+{
+  fn2 ();
+  if (a.f0 != 0)
+    abort ();
+  return 0;
+}