On Wed, Jun 21, 2017 at 08:59:29AM +0200, Richard Biener wrote:
> Actually I was looking for a bit more generic
>
> bool
> target_supports_op_p (tree type, enum tree_code code,
> enum optab_subtype = optab_default)
> {
> optab ot = optab_for_tree_code (code, type, optab_subtype);
> return (ot != unknown_optab
> && optab_handler (ot, TYPE_MODE (type)) != CODE_FOR_nothing);
> }
>
> and you using target_supports_op_p (type, RSHIFT_EXPR, optab_scalar)
> || target_supports_op_p (type, RSHIFT_EXPR, optab_vector)
>
> Ok with that change.
Oh, I see what you mean. Sorry for not getting that correct last time round.
This is what I committed to trunk as revision 249502 after bootstrapping and
testing on aarch64-none-linux-gnu without any issues.
Thanks,
James
gcc/
2017-06-22 James Greenhalgh <[email protected]>
* match.pd (A / (1 << B) -> A >> B): New.
* generic-match-head.c: Include optabs-tree.h.
* gimple-match-head.c: Likewise.
* optabs-tree.h (target_supports_op_p): New.
* optabs-tree.c (target_supports_op_p): New.
gcc/testsuite/
2017-06-22 James Greenhalgh <[email protected]>
* gcc.dg/tree-ssa/forwprop-37.c: New.
diff --git a/gcc/generic-match-head.c b/gcc/generic-match-head.c
index 0c0d182..4504401 100644
--- a/gcc/generic-match-head.c
+++ b/gcc/generic-match-head.c
@@ -33,6 +33,7 @@ along with GCC; see the file COPYING3. If not see
#include "builtins.h"
#include "case-cfn-macros.h"
#include "gimplify.h"
+#include "optabs-tree.h"
/* Routine to determine if the types T1 and T2 are effectively
diff --git a/gcc/gimple-match-head.c b/gcc/gimple-match-head.c
index e7e9839..5f6aa27 100644
--- a/gcc/gimple-match-head.c
+++ b/gcc/gimple-match-head.c
@@ -39,6 +39,7 @@ along with GCC; see the file COPYING3. If not see
#include "internal-fn.h"
#include "case-cfn-macros.h"
#include "gimplify.h"
+#include "optabs-tree.h"
/* Forward declarations of the private auto-generated matchers.
diff --git a/gcc/match.pd b/gcc/match.pd
index 244e9eb..862372a 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -147,6 +147,18 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(op @0 integer_onep)
(non_lvalue @0)))
+/* (A / (1 << B)) -> (A >> B).
+ Only for unsigned A. For signed A, this would not preserve rounding
+ toward zero.
+ For example: (-1 / ( 1 << B)) != -1 >> B. */
+(simplify
+ (trunc_div @0 (lshift integer_onep@1 @2))
+ (if ((TYPE_UNSIGNED (type) || tree_expr_nonnegative_p (@0))
+ && (!VECTOR_TYPE_P (type)
+ || target_supports_op_p (type, RSHIFT_EXPR, optab_vector)
+ || target_supports_op_p (type, RSHIFT_EXPR, optab_scalar)))
+ (rshift @0 @2)))
+
/* Preserve explicit divisions by 0: the C++ front-end wants to detect
undefined behavior in constexpr evaluation, and assuming that the division
traps enables better optimizations than these anyway. */
diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index 4bb54ba..c183b14 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -376,3 +376,18 @@ init_tree_optimization_optabs (tree optnode)
ggc_free (tmp_optabs);
}
}
+
+/* Return TRUE if the target has support for vector right shift of an
+ operand of type TYPE. If OT_TYPE is OPTAB_DEFAULT, check for existence
+ of a shift by either a scalar or a vector. Otherwise, check only
+ for a shift that matches OT_TYPE. */
+
+bool
+target_supports_op_p (tree type, enum tree_code code,
+ enum optab_subtype ot_subtype)
+{
+ optab ot = optab_for_tree_code (code, type, ot_subtype);
+ return (ot != unknown_optab
+ && optab_handler (ot, TYPE_MODE (type)) != CODE_FOR_nothing);
+}
+
diff --git a/gcc/optabs-tree.h b/gcc/optabs-tree.h
index d0b27e0..52e842b 100644
--- a/gcc/optabs-tree.h
+++ b/gcc/optabs-tree.h
@@ -41,5 +41,7 @@ bool supportable_convert_operation (enum tree_code, tree, tree, tree *,
bool expand_vec_cmp_expr_p (tree, tree, enum tree_code);
bool expand_vec_cond_expr_p (tree, tree, enum tree_code);
void init_tree_optimization_optabs (tree);
+bool target_supports_op_p (tree, enum tree_code,
+ enum optab_subtype = optab_default);
#endif
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/forwprop-37.c b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-37.c
new file mode 100644
index 0000000..dec826c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/forwprop-37.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-forwprop1-raw" } */
+
+unsigned int
+f1 (unsigned int a, unsigned int b)
+{
+ unsigned int x = 1U << b;
+ return a / x;
+}
+
+unsigned long
+f2 (unsigned long a, int b)
+{
+ unsigned long x = 1UL << b;
+ return a / x;
+}
+
+unsigned long long
+f3 (unsigned long long a, int b)
+{
+ unsigned long long x = 1ULL << b;
+ return a / x;
+}
+
+/* { dg-final { scan-tree-dump-not "trunc_div_expr" "forwprop1" } } */
