This patch folds svindex with constant arguments into a vector series.
We implemented this in svindex_impl::fold using the function build_vec_series.
For example,
svuint64_t f1 ()
{
return svindex_u642 (10, 3);
}
compiled with -O2 -march=armv8.2-a+sve, is folded to {10, 13, 16, ...}
in the gimple pass lower.
This optimization benefits cases where svindex is used in combination with
other gimple-level optimizations.
For example,
svuint64_t f2 ()
{
return svmul_x (svptrue_b64 (), svindex_u64 (10, 3), 5);
}
has previously been compiled to
f2:
index z0.d, #10, #3
mul z0.d, z0.d, #5
ret
Now, it is compiled to
f2:
mov x0, 50
index z0.d, x0, #15
ret
For non-constant arguments, build_vec_series produces a VEC_SERIES_EXPR,
which is translated back at RTL level to an index instruction without codegen
changes.
We added test cases checking
- the application of the transform during gimple for constant arguments,
- the interaction with another gimple-level optimization.
The patch was bootstrapped and regtested on aarch64-linux-gnu, no regression.
OK for mainline?
Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com>
gcc/
* config/aarch64/aarch64-sve-builtins-base.cc
(svindex_impl::fold): Add constant folding.
gcc/testsuite/
* gcc.target/aarch64/sve/index_const_fold.c: New test.
---
.../aarch64/aarch64-sve-builtins-base.cc | 12 +++++++
.../gcc.target/aarch64/sve/index_const_fold.c | 35 +++++++++++++++++++
2 files changed, 47 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/index_const_fold.c
diff --git a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
index 1c17149e1f0..f6b1657ecbb 100644
--- a/gcc/config/aarch64/aarch64-sve-builtins-base.cc
+++ b/gcc/config/aarch64/aarch64-sve-builtins-base.cc
@@ -1304,6 +1304,18 @@ public:
class svindex_impl : public function_base
{
+public:
+ gimple *
+ fold (gimple_folder &f) const override
+ {
+ tree vec_type = TREE_TYPE (f.lhs);
+ tree base = gimple_call_arg (f.call, 0);
+ tree step = gimple_call_arg (f.call, 1);
+
+ return gimple_build_assign (f.lhs,
+ build_vec_series (vec_type, base, step));
+ }
+
public:
rtx
expand (function_expander &e) const override
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/index_const_fold.c
b/gcc/testsuite/gcc.target/aarch64/sve/index_const_fold.c
new file mode 100644
index 00000000000..f5e6c0f7a85
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/index_const_fold.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+#include <arm_sve.h>
+#include <stdint.h>
+
+#define INDEX_CONST(TYPE, TY) \
+ sv##TYPE f_##TY##_index_const () \
+ { \
+ return svindex_##TY (10, 3); \
+ }
+
+#define MULT_INDEX(TYPE, TY) \
+ sv##TYPE f_##TY##_mult_index () \
+ { \
+ return svmul_x (svptrue_b8 (), \
+ svindex_##TY (10, 3), \
+ 5); \
+ }
+
+#define ALL_TESTS(TYPE, TY) \
+ INDEX_CONST (TYPE, TY) \
+ MULT_INDEX (TYPE, TY)
+
+ALL_TESTS (uint8_t, u8)
+ALL_TESTS (uint16_t, u16)
+ALL_TESTS (uint32_t, u32)
+ALL_TESTS (uint64_t, u64)
+ALL_TESTS (int8_t, s8)
+ALL_TESTS (int16_t, s16)
+ALL_TESTS (int32_t, s32)
+ALL_TESTS (int64_t, s64)
+
+/* { dg-final { scan-tree-dump "return \\{ 10, 13, 16, ... \\}" 8 "optimized"
} } */
+/* { dg-final { scan-tree-dump "return \\{ 50, 65, 80, ... \\}" 8 "optimized"
} } */
--
2.44.0
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