> -----Original Message-----
> From: Richard Guenther [mailto:richard.guent...@gmail.com]
> Sent: Tuesday, March 06, 2012 9:12 PM
> To: Jiangning Liu
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [PATCH] Improve SCEV for array element
>
> On Fri, Jan 20, 2012 at 10:06 AM, Jiangning Liu <jiangning....@arm.com>
> wrote:
> >> It's definitely not ok at this stage but at most for next stage1.
> >
> > OK. I may wait until next stage1.
> >
> >> This is a very narrow pattern-match. It doesn't allow for &a[i].x
> for
> >> example,
> >> even if a[i] is a one-element structure. I think the canonical way
> of
> >> handling
> >> ADDR_EXPR is to use sth like
> >>
> >> base = get_inner_reference (TREE_OPERAND (rhs1, 0), ...,
> &offset, ...);
> >> base = build1 (ADDR_EXPR, TREE_TYPE (rhs1), base);
> >> chrec1 = analyze_scalar_evolution (loop, base);
> >> chrec2 = analyze_scalar_evolution (loop, offset);
> >> chrec1 = chrec_convert (type, chrec1, at_stmt);
> >> chrec2 = chrec_convert (TREE_TYPE (offset), chrec2, at_stmt);
> >> res = chrec_fold_plus (type, chrec1, chrec2);
> >>
> >> where you probably need to handle scev_not_known when analyzing
> offset
> >> (which might be NULL). You also need to add bitpos to the base
> address
> >> (in bytes, of course). Note that the &MEM_REF case would naturally
> >> work
> >> with this as well.
> >
> > OK. New patch is like below, and bootstrapped on x86-32.
>
> You want instead of
>
> + if (TREE_CODE (TREE_OPERAND (rhs1, 0)) == ARRAY_REF
> + || TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
> + || TREE_CODE (TREE_OPERAND (rhs1, 0)) == COMPONENT_REF)
> + {
>
> if (TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
> || handled_component_p (TREE_OPERAND (rhs1, 0)))
> {
>
> + base = build1 (ADDR_EXPR, TREE_TYPE (rhs1), base);
> + chrec1 = analyze_scalar_evolution (loop, base);
>
> can you please add a wrapper
>
> tree
> analyze_scalar_evolution_for_address_of (struct loop *loop, tree var)
> {
> return analyze_scalar_evolution (loop, build_fold_addr_expr (var));
> }
>
> and call that instead of building the ADDR_EXPR there? We want
> to avoid building that tree node, but even such a simple wrapper would
> be prefered.
>
> + if (bitpos)
>
> if (bitpos != 0)
>
> + chrec3 = build_int_cst (integer_type_node,
> + bitpos / BITS_PER_UNIT);
>
> please use size_int (bitpos / BITS_PER_UNIT) instead. Using
> integer_type_node is definitely wrong.
>
> Ok with that changes.
>
Richard,
Modified as all you suggested, and new code is like below. Bootstrapped on
x86-32. OK for trunk now?
Thanks,
-Jiangning
ChangeLog:
2012-03-08 Jiangning Liu <jiangning....@arm.com>
* tree-scalar-evolution (interpret_rhs_expr): generate chrec for
array reference and component reference.
(analyze_scalar_evolution_for_address_of): New.
ChangeLog for testsuite:
2012-03-08 Jiangning Liu <jiangning....@arm.com>
* gcc.dg/tree-ssa/scev-3.c: New.
* gcc.dg/tree-ssa/scev-4.c: New.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/scev-3.c
b/gcc/testsuite/gcc.dg/tree-ssa/scev-3.c
new file mode 100644
index 0000000..28d5c93
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/scev-3.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int *a_p;
+int a[1000];
+
+f(int k)
+{
+ int i;
+
+ for (i=k; i<1000; i+=k) {
+ a_p = &a[i];
+ *a_p = 100;
+ }
+}
+
+/* { dg-final { scan-tree-dump-times "&a" 1 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/scev-4.c
b/gcc/testsuite/gcc.dg/tree-ssa/scev-4.c
new file mode 100644
index 0000000..6c1e530
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/scev-4.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+typedef struct {
+ int x;
+ int y;
+} S;
+
+int *a_p;
+S a[1000];
+
+f(int k)
+{
+ int i;
+
+ for (i=k; i<1000; i+=k) {
+ a_p = &a[i].y;
+ *a_p = 100;
+ }
+}
+
+/* { dg-final { scan-tree-dump-times "&a" 1 "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c
index 2077c8d..c719984
--- a/gcc/tree-scalar-evolution.c
+++ b/gcc/tree-scalar-evolution.c
@@ -266,6 +266,8 @@ along with GCC; see the file COPYING3. If not see
#include "params.h"
static tree analyze_scalar_evolution_1 (struct loop *, tree, tree);
+static tree analyze_scalar_evolution_for_address_of (struct loop *loop,
+ tree var);
/* The cached information about an SSA name VAR, claiming that below
basic block INSTANTIATED_BELOW, the value of VAR can be expressed
@@ -1712,16 +1714,59 @@ interpret_rhs_expr (struct loop *loop, gimple
at_stmt,
switch (code)
{
case ADDR_EXPR:
- /* Handle &MEM[ptr + CST] which is equivalent to POINTER_PLUS_EXPR.
*/
- if (TREE_CODE (TREE_OPERAND (rhs1, 0)) != MEM_REF)
- {
- res = chrec_dont_know;
- break;
- }
+ if (TREE_CODE (TREE_OPERAND (rhs1, 0)) == MEM_REF
+ || handled_component_p (TREE_OPERAND (rhs1, 0)))
+ {
+ enum machine_mode mode;
+ HOST_WIDE_INT bitsize, bitpos;
+ int unsignedp;
+ int volatilep = 0;
+ tree base, offset;
+ tree chrec3;
+ tree unitpos;
+
+ base = get_inner_reference (TREE_OPERAND (rhs1, 0),
+ &bitsize, &bitpos, &offset,
+ &mode, &unsignedp, &volatilep, false);
+
+ if (TREE_CODE (base) == MEM_REF)
+ {
+ rhs2 = TREE_OPERAND (base, 1);
+ rhs1 = TREE_OPERAND (base, 0);
+
+ chrec1 = analyze_scalar_evolution (loop, rhs1);
+ chrec2 = analyze_scalar_evolution (loop, rhs2);
+ chrec1 = chrec_convert (type, chrec1, at_stmt);
+ chrec2 = chrec_convert (TREE_TYPE (rhs2), chrec2, at_stmt);
+ res = chrec_fold_plus (type, chrec1, chrec2);
+ }
+ else
+ {
+ chrec1 = analyze_scalar_evolution_for_address_of (loop, base);
+ chrec1 = chrec_convert (type, chrec1, at_stmt);
+ res = chrec1;
+ }
+
+ if (offset != NULL_TREE)
+ {
+ chrec2 = analyze_scalar_evolution (loop, offset);
+ chrec2 = chrec_convert (TREE_TYPE (offset), chrec2, at_stmt);
+ res = chrec_fold_plus (type, res, chrec2);
+ }
+
+ if (bitpos != 0)
+ {
+ gcc_assert ((bitpos % BITS_PER_UNIT) == 0);
- rhs2 = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 1);
- rhs1 = TREE_OPERAND (TREE_OPERAND (rhs1, 0), 0);
- /* Fall through. */
+ unitpos = size_int_kind (bitpos / BITS_PER_UNIT, SIZETYPE);
+ chrec3 = analyze_scalar_evolution (loop, unitpos);
+ chrec3 = chrec_convert (TREE_TYPE (unitpos), chrec3, at_stmt);
+ res = chrec_fold_plus (type, res, chrec3);
+ }
+ }
+ else
+ res = chrec_dont_know;
+ break;
case POINTER_PLUS_EXPR:
chrec1 = analyze_scalar_evolution (loop, rhs1);
@@ -1961,6 +2006,14 @@ analyze_scalar_evolution (struct loop *loop, tree
var)
return res;
}
+/* Analyzes and returns the scalar evolution of VAR address in LOOP. */
+
+static tree
+analyze_scalar_evolution_for_address_of (struct loop *loop, tree var)
+{
+ return analyze_scalar_evolution (loop, build_fold_addr_expr (var));
+}
+
/* Analyze scalar evolution of use of VERSION in USE_LOOP with respect to
WRTO_LOOP (which should be a superloop of USE_LOOP)
