[PATCH] RISC-V: Add norelax function attribute

[shiyulong]

From: yulong <shiyul...@iscas.ac.cn>

This patch adds norelax function attribute that be discussed in riscv-c-api-doc 
PR#94.
URL:https://github.com/riscv-non-isa/riscv-c-api-doc/pull/94

gcc/ChangeLog:

        * config/riscv/riscv.cc (riscv_declare_function_name): Add new 
attribute.

---
 gcc/config/riscv/riscv.cc                     | 18 +++++++++++++---
 .../gcc.target/riscv/target-attr-norelax.c    | 21 +++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/target-attr-norelax.c

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 2e9ac280c8f2..42525ff6faa3 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -654,6 +654,10 @@ static const attribute_spec riscv_gnu_attributes[] =
      types.  */
   {"riscv_rvv_vector_bits", 1, 1, false, true, false, true,
    riscv_handle_rvv_vector_bits_attribute, NULL},
+  /* This attribute is used to declare a function, forcing it to use the
+    standard vector calling convention variant. Syntax:
+    __attribute__((norelax)). */
+  {"norelax", 0, 0, true, false, false, false, NULL, NULL},
 };
 
 static const scoped_attribute_specs riscv_gnu_attribute_table  =
@@ -10051,10 +10055,17 @@ riscv_declare_function_name (FILE *stream, const char 
*name, tree fndecl)
   riscv_asm_output_variant_cc (stream, fndecl, name);
   ASM_OUTPUT_TYPE_DIRECTIVE (stream, name, "function");
   ASM_OUTPUT_FUNCTION_LABEL (stream, name, fndecl);
-  if (DECL_FUNCTION_SPECIFIC_TARGET (fndecl))
+  if (DECL_FUNCTION_SPECIFIC_TARGET (fndecl)
+      || lookup_attribute ("norelax", DECL_ATTRIBUTES (fndecl)))
     {
       fprintf (stream, "\t.option push\n");
-
+      if (lookup_attribute ("norelax", DECL_ATTRIBUTES (fndecl)))
+       {
+         fprintf (stream, "\t.option norelax\n");
+       }
+    }
+  if (DECL_FUNCTION_SPECIFIC_TARGET (fndecl))
+    {
       struct cl_target_option *local_cl_target =
        TREE_TARGET_OPTION (DECL_FUNCTION_SPECIFIC_TARGET (fndecl));
       struct cl_target_option *global_cl_target =
@@ -10078,7 +10089,8 @@ riscv_declare_function_size (FILE *stream, const char 
*name, tree fndecl)
   if (!flag_inhibit_size_directive)
     ASM_OUTPUT_MEASURED_SIZE (stream, name);
 
-  if (DECL_FUNCTION_SPECIFIC_TARGET (fndecl))
+  if (DECL_FUNCTION_SPECIFIC_TARGET (fndecl)
+      || lookup_attribute ("norelax", DECL_ATTRIBUTES (fndecl)))
     {
       fprintf (stream, "\t.option pop\n");
     }
diff --git a/gcc/testsuite/gcc.target/riscv/target-attr-norelax.c 
b/gcc/testsuite/gcc.target/riscv/target-attr-norelax.c
new file mode 100644
index 000000000000..77de6195ad1e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/target-attr-norelax.c
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv32gc" { target { rv32 } } } */
+/* { dg-options "-march=rv64gc" { target { rv64 } } } */
+
+__attribute__((norelax))
+void foo1()
+{}
+
+void foo2(void)
+{}
+
+int main()
+{
+  foo1();
+  foo2();
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times ".option push\t" 1 } } */
+/* { dg-final { scan-assembler-times ".option norelax\t" 1 } } */
+/* { dg-final { scan-assembler-times ".option pop\t" 1 } } */
-- 
2.34.1