[PATCH v4] RISC-V: Adds the prefix "th." for the instructions of XTheadVector.

["Jun Sha (Joshua)" <cooper.joshua@linux.alibaba.com>]

This patch adds th. prefix to all XTheadVector instructions by
implementing new assembly output functions. We only check the
prefix is 'v', so that no extra attribute is needed.

gcc/ChangeLog:

	* config/riscv/riscv-protos.h (riscv_asm_output_opcode):
	New function to add assembler insn code prefix/suffix.
	(th_asm_output_opcode):
	Thead function to add assembler insn code prefix/suffix.
	* config/riscv/riscv.cc (riscv_asm_output_opcode): Likewise
	* config/riscv/riscv.h (ASM_OUTPUT_OPCODE): Likewise.
	* config/riscv/thead.cc (th_asm_output_opcode): Likewise

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/xtheadvector/prefix.c: New test.

Co-authored-by: Jin Ma <jinma@linux.alibaba.com>
Co-authored-by: Xianmiao Qu <cooper.qu@linux.alibaba.com>
Co-authored-by: Christoph Müllner <christoph.muellner@vrull.eu>
---
 gcc/config/riscv/riscv-protos.h                     |  2 ++
 gcc/config/riscv/riscv.cc                           | 11 +++++++++++
 gcc/config/riscv/riscv.h                            |  4 ++++
 gcc/config/riscv/thead.cc                           | 13 +++++++++++++
 .../gcc.target/riscv/rvv/xtheadvector/prefix.c      | 12 ++++++++++++
 5 files changed, 42 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/prefix.c

diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index 31049ef7523..71724dabdb5 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -102,6 +102,7 @@ struct riscv_address_info {
 };
 
 /* Routines implemented in riscv.cc.  */
+extern const char *riscv_asm_output_opcode (FILE *asm_out_file, const char *p);
 extern enum riscv_symbol_type riscv_classify_symbolic_expression (rtx);
 extern bool riscv_symbolic_constant_p (rtx, enum riscv_symbol_type *);
 extern int riscv_float_const_rtx_index_for_fli (rtx);
@@ -717,6 +718,7 @@ extern void th_mempair_prepare_save_restore_operands (rtx[4], bool,
 						      int, HOST_WIDE_INT,
 						      int, HOST_WIDE_INT);
 extern void th_mempair_save_restore_regs (rtx[4], bool, machine_mode);
+extern const char *th_asm_output_opcode (FILE *asm_out_file, const char *p);
 #ifdef RTX_CODE
 extern const char*
 th_mempair_output_move (rtx[4], bool, machine_mode, RTX_CODE);
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 0d1cbc5cb5f..51878797287 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -5636,6 +5636,17 @@ riscv_get_v_regno_alignment (machine_mode mode)
   return lmul;
 }
 
+/* Define ASM_OUTPUT_OPCODE to do anything special before
+   emitting an opcode.  */
+const char *
+riscv_asm_output_opcode (FILE *asm_out_file, const char *p)
+{
+  if (TARGET_XTHEADVECTOR)
+    return th_asm_output_opcode (asm_out_file, p);
+
+  return p;
+}
+
 /* Implement TARGET_PRINT_OPERAND.  The RISCV-specific operand codes are:
 
    'h'	Print the high-part relocation associated with OP, after stripping
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index 6df9ec73c5e..c33361a254d 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -826,6 +826,10 @@ extern enum riscv_cc get_riscv_cc (const rtx use);
       asm_fprintf ((FILE), "%U%s", (NAME));				\
   } while (0)
 
+#undef ASM_OUTPUT_OPCODE
+#define ASM_OUTPUT_OPCODE(STREAM, PTR)	\
+  (PTR) = riscv_asm_output_opcode(STREAM, PTR)
+
 #define JUMP_TABLES_IN_TEXT_SECTION 0
 #define CASE_VECTOR_MODE SImode
 #define CASE_VECTOR_PC_RELATIVE (riscv_cmodel != CM_MEDLOW)
diff --git a/gcc/config/riscv/thead.cc b/gcc/config/riscv/thead.cc
index 20353995931..dc3aed3904d 100644
--- a/gcc/config/riscv/thead.cc
+++ b/gcc/config/riscv/thead.cc
@@ -883,6 +883,19 @@ th_output_move (rtx dest, rtx src)
   return NULL;
 }
 
+/* Define ASM_OUTPUT_OPCODE to do anything special before
+   emitting an opcode.  */
+const char *
+th_asm_output_opcode (FILE *asm_out_file, const char *p)
+{
+  /* We need to add th. prefix to all the xtheadvector
+     instructions here.*/
+  if (current_output_insn != NULL && p[0] == 'v')
+    fputs ("th.", asm_out_file);
+
+  return p;
+}
+
 /* Implement TARGET_PRINT_OPERAND_ADDRESS for XTheadMemIdx.  */
 
 bool
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/prefix.c b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/prefix.c
new file mode 100644
index 00000000000..eee727ef6b4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/prefix.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gc_xtheadvector -mabi=ilp32 -O0" } */
+
+#include "riscv_vector.h"
+
+vint32m1_t
+prefix (vint32m1_t vx, vint32m1_t vy, size_t vl)
+{
+  return __riscv_vadd_vv_i32m1 (vx, vy, vl);
+}
+
+/* { dg-final { scan-assembler {\mth\.v\M} } } */
-- 
2.17.1