i#3544 RV64: Port client.flush to riscv64 (#7438)

Marking the interested basic block with one uncompressed NOP (4 bytes)
and two compressed NOPs (2 x 2 bytes). This pattern should happen rarely
in compiler-generated code, since two compressed NOPs could always be
replaced with a compressed one.

Issue: #3544

Author: ziyao233

suite/tests/CMakeLists.txt

@@ -2832,12 +2832,12 @@ if (NOT APPLE OR NOT AARCH64 AND NOT MUSL)
   tobuild_ci(client.file_io client-interface/file_io.c
     "${CMAKE_CURRENT_SOURCE_DIR}/client-interface/file_io_data.txt" "" "")
 endif ()
-if (X86 OR AARCH64) # FIXME i#1551: port asm to ARM
+if (X86 OR AARCH64 OR RISCV64) # FIXME i#1551: port asm to ARM
   if (DEBUG) # FIXME i#1806: fails in release; also in OSX list below.
     # we add custom option to flush test based on dr ops in torun_ci()
     tobuild_ci(client.flush client-interface/flush.c "" "" "")
   endif ()
-endif (X86 OR AARCH64)
+endif (X86 OR AARCH64 OR RISCV64)
 if (X86 OR AARCH64) # FIXME i#1551: port asm to ARM
   tobuild_ci(client.strace client-interface/strace.c "" "" "")
   use_DynamoRIO_extension(client.strace.dll drmgr)
@@ -6674,6 +6674,7 @@ if (RISCV64)
     code_api|client.crashmsg
     code_api|client.drwrap-test-callconv
     code_api|client.execfault
+    code_api|client.flush
     code_api|client.mangle_suspend
     code_api|client.null_instrument
     code_api|client.option_parse

suite/tests/client-interface/flush.c

@@ -83,6 +83,13 @@ GLOBAL_LABEL(marker:)
         yield
         yield
         ret
+#elif defined (RISCV64)
+        nop
+        .option arch, +c
+        c.nop
+        c.nop
+        .option arch, -c
+        ret
 #endif
         END_FUNC(marker)
 END_FILE

suite/tests/client-interface/flush.dll.c

@@ -263,6 +263,14 @@ check_for_marker(instr_t *first_inst)
                 if (third != NULL && instr_get_opcode(third) == OP_yield)
                     return true;
             }
+#elif defined(RISCV64)
+            /* For RISCV64 look for an uncompressed nop followed by two compressed
+             * ones */
+            if (instr_get_opcode(second) == OP_c_nop) {
+                instr_t *third = instr_get_next(second);
+                if (third != NULL && instr_get_opcode(third) == OP_c_nop)
+                    return true;
+            }
 #endif
         }
     }