RISC-V: Implement -mmemcpy-strategy= options[PR112537]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112537

-mmemcpy-strategy=[auto|libcall|scalar|vector]

auto: Current status, use scalar or vector instructions.
libcall: Always use a library call.
scalar: Only use scalar instructions.
vector: Only use vector instructions.

	PR target/112537

gcc/ChangeLog:

	* config/riscv/riscv-opts.h (enum riscv_stringop_strategy_enum): Strategy enum.
	* config/riscv/riscv-string.cc (riscv_expand_block_move): Disabled based on options.
	(expand_block_move): Ditto.
	* config/riscv/riscv.opt: Add -mmemcpy-strategy=.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/cpymem-strategy-1.c: New test.
	* gcc.target/riscv/rvv/base/cpymem-strategy-2.c: New test.
	* gcc.target/riscv/rvv/base/cpymem-strategy-3.c: New test.
	* gcc.target/riscv/rvv/base/cpymem-strategy-4.c: New test.
	* gcc.target/riscv/rvv/base/cpymem-strategy-5.c: New test.
	* gcc.target/riscv/rvv/base/cpymem-strategy.h: New test.

9 files changed, 80 insertions, 1 deletions

diff --git a/gcc/config/riscv/riscv-opts.h b/gcc/config/riscv/riscv-opts.h
index 532b1b6..0b242f0 100644
--- a/gcc/config/riscv/riscv-opts.h
+++ b/gcc/config/riscv/riscv-opts.h
@@ -102,6 +102,18 @@ enum riscv_entity
   MAX_RISCV_ENTITIES
 };
 
+/* RISC-V stringop strategy. */
+enum riscv_stringop_strategy_enum {
+  /* Use scalar or vector instructions. */
+  USE_AUTO,
+  /* Always use a library call. */
+  USE_LIBCALL,
+  /* Only use scalar instructions. */
+  USE_SCALAR,
+  /* Only use vector instructions. */
+  USE_VECTOR
+};
+
 #define TARGET_ZICOND_LIKE (TARGET_ZICOND || (TARGET_XVENTANACONDOPS && TARGET_64BIT))
 
 /* Bit of riscv_zvl_flags will set contintuly, N-1 bit will set if N-bit is
diff --git a/gcc/config/riscv/riscv-string.cc b/gcc/config/riscv/riscv-string.cc
index 57e8ad6..3b5e05e 100644
--- a/gcc/config/riscv/riscv-string.cc
+++ b/gcc/config/riscv/riscv-string.cc
@@ -710,6 +710,10 @@ riscv_block_move_loop (rtx dest, rtx src, unsigned HOST_WIDE_INT length,
 bool
 riscv_expand_block_move (rtx dest, rtx src, rtx length)
 {
+  if (riscv_memcpy_strategy == USE_LIBCALL
+      || riscv_memcpy_strategy == USE_VECTOR)
+    return false;
+
   if (CONST_INT_P (length))
     {
       unsigned HOST_WIDE_INT hwi_length = UINTVAL (length);
@@ -773,7 +777,8 @@ expand_block_move (rtx dst_in, rtx src_in, rtx length_in)
 	bnez a2, loop                   # Any more?
 	ret                             # Return
   */
-  if (!TARGET_VECTOR)
+  if (!TARGET_VECTOR || riscv_memcpy_strategy == USE_LIBCALL
+      || riscv_memcpy_strategy == USE_SCALAR)
     return false;
   HOST_WIDE_INT potential_ew
     = (MIN (MIN (MEM_ALIGN (src_in), MEM_ALIGN (dst_in)), BITS_PER_WORD)
diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 1bd661a..555288e 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -527,3 +527,23 @@ Target Var(TARGET_ADJUST_LMUL_COST) Init(0)
 Target Undocumented Bool Var(riscv_vector_abi) Init(0)
 Enable the use of vector registers for function arguments and return value.
 This is an experimental switch and may be subject to change in the future.
+
+Enum
+Name(riscv_stringop_strategy) Type(enum riscv_stringop_strategy_enum)
+Valid arguments to -mmemcpy-strategy=:
+
+EnumValue
+Enum(riscv_stringop_strategy) String(auto) Value(USE_AUTO)
+
+EnumValue
+Enum(riscv_stringop_strategy) String(libcall) Value(USE_LIBCALL)
+
+EnumValue
+Enum(riscv_stringop_strategy) String(scalar) Value(USE_SCALAR)
+
+EnumValue
+Enum(riscv_stringop_strategy) String(vector) Value(USE_VECTOR)
+
+mmemcpy-strategy=
+Target RejectNegative Joined Enum(riscv_stringop_strategy) Var(riscv_memcpy_strategy) Init(USE_AUTO)
+Specify memcpy expansion strategy.
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-1.c b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-1.c
new file mode 100644
index 0000000..ae49706
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-1.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -mmemcpy-strategy=libcall" } */
+
+#include "cpymem-strategy.h"
+
+/* { dg-final { scan-assembler-times {call\tmemcpy} 2 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-2.c b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-2.c
new file mode 100644
index 0000000..73ffc57
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-2.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=rv32gcv -mabi=ilp32d -mmemcpy-strategy=scalar" } */
+
+#include "cpymem-strategy.h"
+
+/* { dg-final { scan-assembler-times {call\tmemcpy} 1 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-3.c b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-3.c
new file mode 100644
index 0000000..44f5f78
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-3.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -mmemcpy-strategy=vector" } */
+
+#include "cpymem-strategy.h"
+
+/* { dg-final { scan-assembler-times {v[ls]+e[0-9]+\.v\tv[0-9]+\,0\([a-z0-9]+\)} 4 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-4.c b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-4.c
new file mode 100644
index 0000000..8056895
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-4.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gcv -mabi=ilp32d -mmemcpy-strategy=auto" } */
+
+#include "cpymem-strategy.h"
+
+/* { dg-final { scan-assembler-times {v[ls]+e[0-9]+\.v\tv[0-9]+\,0\([a-z0-9]+\)} 4 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-5.c b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-5.c
new file mode 100644
index 0000000..82ecab0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy-5.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gc -mabi=ilp32d -mmemcpy-strategy=vector" } */
+
+#include "cpymem-strategy.h"
+
+/* { dg-final { scan-assembler-times {call\tmemcpy} 2 } } */
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy.h b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy.h
new file mode 100644
index 0000000..700d224
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/base/cpymem-strategy.h
@@ -0,0 +1,12 @@
+typedef struct { unsigned char a[56]; } a56;
+typedef struct { int b[32]; } b32;
+
+void f1 (a56 *v1, a56 *v2)
+{
+    *v1 = *v2;
+}
+
+void f2 (b32 *v1, b32 *v2)
+{
+    *v1 = *v2;
+}