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Re: PATCH: PR tree-optimization/35494: [4.4 Regression]: Revision 132991 breaks 483.xalancbmk
Compiler will allocate space for
const int conststaticvariable;
You just may not know what value will be in all cases. Here is the
updated with additional testcases. OK to install if tests on Linux/x86
and Linux/Intel64 as well as 483.xalancbmk passes?
H.J.
On Fri, Mar 7, 2008 at 9:00 AM, Andrew Pinski <pinskia@gmail.com> wrote:
> On 3/7/08, H.J. Lu <hjl.tools@gmail.com> wrote:
> > We can't fold glocal variables with NULL DECL_INITIAL. I am testing it
> > on Linux/x86 and Linux/Intel64 as well as 483.xalancbmk. OK to install
> > if all pass?
>
> This patch is wrong because currently we check TREE_STATIC which says
> we allocate space for the variable:
> /* In a VAR_DECL, nonzero means allocate static storage.
> In a FUNCTION_DECL, nonzero if function has been defined.
> In a CONSTRUCTOR, nonzero means allocate static storage.
>
> ??? This is also used in lots of other nodes in unclear ways which
> should be cleaned up some day. */
>
> TREE_STATIC should not be set on those variables as there is no space
> allocated in the case of the C++ case (I think Ada case also).
>
> Also "const int conststaticvariable;" in C is global but it will be
> put in the common section and is called a tentative definition. So
> there needs to be another check for that instead of just TREE_PUBLIC.
> That is if you compile:
>
> const int conststaticvariable;
>
> int f(void)
> {
> return conststaticvariable;
> }
> With -fno-common, the tentative definition is no longer one and we
> should be able to optimize it.
>
> Thanks,
> Andrew Pinski
>
gcc/testsuite/
2008-03-07 H.J. Lu <hongjiu.lu@intel.com>
PR tree-optimization/35494
* g++.dg/tree-ssa/ssa-store-ccp-1.C: New.
* gcc.dg/tree-ssa/ssa-store-ccp-2.c: Likewise.
* gcc.dg/tree-ssa/ssa-store-ccp-3.c: Likewise.
* gcc.dg/tree-ssa/ssa-store-ccp-4.c: Likewise.
gcc/
2008-03-07 H.J. Lu <hongjiu.lu@intel.com>
PR tree-optimization/35494
* tree-ssa-ccp.c (get_symbol_constant_value): Only fold local
variables with NULL DECL_INITIAL.
--- gcc/testsuite/g++.dg/tree-ssa/ssa-store-ccp-1.C.local 2008-03-07 09:28:35.000000000 -0800
+++ gcc/testsuite/g++.dg/tree-ssa/ssa-store-ccp-1.C 2008-03-07 09:28:35.000000000 -0800
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+class bar
+{
+public:
+ static const int conststaticvariable;
+};
+
+
+int f(void)
+{
+ return bar::conststaticvariable;
+}
+
+/* There should be a reference to conststaticvariable since it is
+ global. */
+/* { dg-final { scan-tree-dump-times "conststaticvariable" 1 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-2.c.local 2008-03-07 09:28:35.000000000 -0800
+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-2.c 2008-03-07 09:28:35.000000000 -0800
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+const int conststaticvariable;
+
+int f(void)
+{
+ return conststaticvariable;
+}
+
+/* There should be a reference to conststaticvariable since it is
+ global. */
+/* { dg-final { scan-tree-dump-times "conststaticvariable" 1 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-3.c.local 2008-03-07 09:34:05.000000000 -0800
+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-3.c 2008-03-07 09:57:03.000000000 -0800
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-common -fdump-tree-optimized" } */
+
+const int conststaticvariable;
+
+int f(void)
+{
+ return conststaticvariable;
+}
+
+/* There should be no reference to conststaticvariable as we should have
+ inlined the 0. */
+/* { dg-final { scan-tree-dump-times "conststaticvariable" 0 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-4.c.local 2008-03-07 11:03:04.000000000 -0800
+++ gcc/testsuite/gcc.dg/tree-ssa/ssa-store-ccp-4.c 2008-03-07 11:02:00.000000000 -0800
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-O2 -fno-common -fpic -fdump-tree-optimized" } */
+
+const int conststaticvariable;
+
+int f(void)
+{
+ return conststaticvariable;
+}
+
+/* There should be a reference to conststaticvariable since it is
+ global. */
+/* { dg-final { scan-tree-dump-times "conststaticvariable" 1 "optimized"} } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */
--- gcc/tree-ssa-ccp.c.local 2008-03-07 09:02:37.000000000 -0800
+++ gcc/tree-ssa-ccp.c 2008-03-07 10:59:07.000000000 -0800
@@ -306,9 +306,12 @@ get_symbol_constant_value (tree sym)
if (val
&& ccp_decl_initial_min_invariant (val))
return val;
- /* Variables declared 'const' without an initializer
+ /* Local variables declared 'const' without an initializer
have zero as the intializer. */
if (!val
+ && (!TREE_PUBLIC (sym)
+ || (!DECL_EXTERNAL (sym)
+ && targetm.binds_local_p (sym)))
&& (INTEGRAL_TYPE_P (TREE_TYPE (sym))
|| SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
return fold_convert (TREE_TYPE (sym), integer_zero_node);