[PATCH] Fix PR87985
Richard Biener
rguenther@suse.de
Wed Nov 14 14:31:00 GMT 2018
On Mon, 12 Nov 2018, Richard Biener wrote:
>
> The following fixes split_constant_offset unbound un-CSEing of
> expressions when following SSA def stmts. Simply limiting it to
> single-uses isn't good for consumers so the following instead
> limits analysis by implementing a cache. Note this may still
> end up un-CSEing stuff but I didn't want to try inserting
> SAVE_EXPRs in split_constant_offset result... (maybe I should
> simply try though...). Another option would be to give up
> when we see several uses of an "interesting" expression, thus
> make the hash-map a visited thing instead (but the result would
> be somewhat odd I guess).
>
> Anyway, the following preserves existing behavior while fixing
> the compile-time issue for the testcase (which doesn't end up
> generating anything interesting).
So I sneaked in "obvious" changes not expanding stuff without
contributions to the constant. Obviously that broke some
vectorizer tests where for dependence analysis we have to have
1:1 matching bases and ptr + (sizetype)i[+ 0] vs. ptr + (sizetype)(i+4)
was expanded inconsistently. I've take out those changes and
committed the following instead.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Richard.
>From 111674b00c850e849c66ab569a63c6ff7466110a Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguenther@suse.de>
Date: Mon, 12 Nov 2018 14:45:27 +0100
Subject: [PATCH] fix-pr87985
PR middle-end/87985
* tree-data-ref.c (split_constant_offset): Add wrapper
allocating a cache hash-map.
(split_constant_offset_1): Cache results of expanding
expressions from SSA def stmts.
* gcc.dg/pr87985.c: New testcase.
diff --git a/gcc/testsuite/gcc.dg/pr87985.c b/gcc/testsuite/gcc.dg/pr87985.c
new file mode 100644
index 00000000000..c0d07ff918f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr87985.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-slp-vectorize" } */
+
+char *bar (void);
+__INTPTR_TYPE__ baz (void);
+
+void
+foo (__INTPTR_TYPE__ *q)
+{
+ char *p = bar ();
+ __INTPTR_TYPE__ a = baz ();
+ __INTPTR_TYPE__ b = baz ();
+ int i = 0;
+#define X q[i++] = a; q[i++] = b; a = a + b; b = b + a;
+#define Y X X X X X X X X X X
+#define Z Y Y Y Y Y Y Y Y Y Y
+ Z Z Z Z Z Z Z Z Z Z
+ p[a] = 1;
+ p[b] = 2;
+}
diff --git a/gcc/tree-data-ref.c b/gcc/tree-data-ref.c
index 6019c6168bf..0096afb9ba7 100644
--- a/gcc/tree-data-ref.c
+++ b/gcc/tree-data-ref.c
@@ -95,10 +95,8 @@ along with GCC; see the file COPYING3. If not see
#include "tree-affine.h"
#include "params.h"
#include "builtins.h"
-#include "stringpool.h"
-#include "tree-vrp.h"
-#include "tree-ssanames.h"
#include "tree-eh.h"
+#include "ssa.h"
static struct datadep_stats
{
@@ -584,6 +582,10 @@ debug_ddrs (vec<ddr_p> ddrs)
dump_ddrs (stderr, ddrs);
}
+static void
+split_constant_offset (tree exp, tree *var, tree *off,
+ hash_map<tree, std::pair<tree, tree> > &cache);
+
/* Helper function for split_constant_offset. Expresses OP0 CODE OP1
(the type of the result is TYPE) as VAR + OFF, where OFF is a nonzero
constant of type ssizetype, and returns true. If we cannot do this
@@ -592,7 +594,8 @@ debug_ddrs (vec<ddr_p> ddrs)
static bool
split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
- tree *var, tree *off)
+ tree *var, tree *off,
+ hash_map<tree, std::pair<tree, tree> > &cache)
{
tree var0, var1;
tree off0, off1;
@@ -613,8 +616,8 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
/* FALLTHROUGH */
case PLUS_EXPR:
case MINUS_EXPR:
- split_constant_offset (op0, &var0, &off0);
- split_constant_offset (op1, &var1, &off1);
+ split_constant_offset (op0, &var0, &off0, cache);
+ split_constant_offset (op1, &var1, &off1, cache);
*var = fold_build2 (code, type, var0, var1);
*off = size_binop (ocode, off0, off1);
return true;
@@ -623,7 +626,7 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
if (TREE_CODE (op1) != INTEGER_CST)
return false;
- split_constant_offset (op0, &var0, &off0);
+ split_constant_offset (op0, &var0, &off0, cache);
*var = fold_build2 (MULT_EXPR, type, var0, op1);
*off = size_binop (MULT_EXPR, off0, fold_convert (ssizetype, op1));
return true;
@@ -647,7 +650,7 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
if (poffset)
{
- split_constant_offset (poffset, &poffset, &off1);
+ split_constant_offset (poffset, &poffset, &off1, cache);
off0 = size_binop (PLUS_EXPR, off0, off1);
if (POINTER_TYPE_P (TREE_TYPE (base)))
base = fold_build_pointer_plus (base, poffset);
@@ -691,18 +694,48 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
if (gimple_code (def_stmt) != GIMPLE_ASSIGN)
return false;
- var0 = gimple_assign_rhs1 (def_stmt);
subcode = gimple_assign_rhs_code (def_stmt);
+
+ /* We are using a cache to avoid un-CSEing large amounts of code. */
+ bool use_cache = false;
+ if (!has_single_use (op0)
+ && (subcode == POINTER_PLUS_EXPR
+ || subcode == PLUS_EXPR
+ || subcode == MINUS_EXPR
+ || subcode == MULT_EXPR
+ || subcode == ADDR_EXPR
+ || CONVERT_EXPR_CODE_P (subcode)))
+ {
+ use_cache = true;
+ bool existed;
+ std::pair<tree, tree> &e = cache.get_or_insert (op0, &existed);
+ if (existed)
+ {
+ if (integer_zerop (e.second))
+ return false;
+ *var = e.first;
+ *off = e.second;
+ return true;
+ }
+ e = std::make_pair (op0, ssize_int (0));
+ }
+
+ var0 = gimple_assign_rhs1 (def_stmt);
var1 = gimple_assign_rhs2 (def_stmt);
- return split_constant_offset_1 (type, var0, subcode, var1, var, off);
+ bool res = split_constant_offset_1 (type, var0, subcode, var1,
+ var, off, cache);
+ if (res && use_cache)
+ *cache.get (op0) = std::make_pair (*var, *off);
+ return res;
}
CASE_CONVERT:
{
- /* We must not introduce undefined overflow, and we must not change the value.
- Hence we're okay if the inner type doesn't overflow to start with
- (pointer or signed), the outer type also is an integer or pointer
- and the outer precision is at least as large as the inner. */
+ /* We must not introduce undefined overflow, and we must not change
+ the value. Hence we're okay if the inner type doesn't overflow
+ to start with (pointer or signed), the outer type also is an
+ integer or pointer and the outer precision is at least as large
+ as the inner. */
tree itype = TREE_TYPE (op0);
if ((POINTER_TYPE_P (itype)
|| (INTEGRAL_TYPE_P (itype) && !TYPE_OVERFLOW_TRAPS (itype)))
@@ -714,7 +747,7 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
/* Split the unconverted operand and try to prove that
wrapping isn't a problem. */
tree tmp_var, tmp_off;
- split_constant_offset (op0, &tmp_var, &tmp_off);
+ split_constant_offset (op0, &tmp_var, &tmp_off, cache);
/* See whether we have an SSA_NAME whose range is known
to be [A, B]. */
@@ -749,7 +782,7 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
*off = wide_int_to_tree (ssizetype, diff);
}
else
- split_constant_offset (op0, &var0, off);
+ split_constant_offset (op0, &var0, off, cache);
*var = fold_convert (type, var0);
return true;
}
@@ -764,8 +797,9 @@ split_constant_offset_1 (tree type, tree op0, enum tree_code code, tree op1,
/* Expresses EXP as VAR + OFF, where off is a constant. The type of OFF
will be ssizetype. */
-void
-split_constant_offset (tree exp, tree *var, tree *off)
+static void
+split_constant_offset (tree exp, tree *var, tree *off,
+ hash_map<tree, std::pair<tree, tree> > &cache)
{
tree type = TREE_TYPE (exp), op0, op1, e, o;
enum tree_code code;
@@ -779,13 +813,23 @@ split_constant_offset (tree exp, tree *var, tree *off)
code = TREE_CODE (exp);
extract_ops_from_tree (exp, &code, &op0, &op1);
- if (split_constant_offset_1 (type, op0, code, op1, &e, &o))
+ if (split_constant_offset_1 (type, op0, code, op1, &e, &o, cache))
{
*var = e;
*off = o;
}
}
+void
+split_constant_offset (tree exp, tree *var, tree *off)
+{
+ static hash_map<tree, std::pair<tree, tree> > *cache;
+ if (!cache)
+ cache = new hash_map<tree, std::pair<tree, tree> > (37);
+ split_constant_offset (exp, var, off, *cache);
+ cache->empty ();
+}
+
/* Returns the address ADDR of an object in a canonical shape (without nop
casts, and with type of pointer to the object). */
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