const char compile_name vs. HS_DTRACE_PROBE?

[Peter B. Kessler]

I can also work around this issue by

     export HOTSPOT_DISABLE_DTRACE_PROBES=1

but that seems like a band-aid.

			... peter

On 05/06/13 13:14, Peter B. Kessler wrote:
> CompileBroker::compiler_name(int) is declared[1]
>
>        231 // Compilation
>        232 //
>        233 // The broker for all compilation requests.
>        234 class CompileBroker: AllStatic {
>        ...
>        422   // compiler name for debugging
>        423   static const char* compiler_name(int comp_level);
>        424 };
>
> and is used from[2]
>
>       1731 // Compile a method.
>       1732 //
>       1733 void CompileBroker::invoke_compiler_on_method(CompileTask* task) {
>       ...
>       1769     DTRACE_METHOD_COMPILE_BEGIN_PROBE(compiler(task_level), method,
>       1770                                       compiler_name(task_level));
>       ...
>       1850   DTRACE_METHOD_COMPILE_END_PROBE(compiler(task_level), method,
>       1851                                   compiler_name(task_level), task->is_success());
>
> But DTRACE_METHOD_COMPILE_BEGIN_PROBE and DTRACE_METHOD_COMPILE_END_PROBE are "declared" by
>
>         95 #define DTRACE_METHOD_COMPILE_BEGIN_PROBE(compiler, method, comp_name)   \
>         96   {                                                                      \
>        ...                            \
>        100     HOTSPOT_METHOD_COMPILE_BEGIN(                                        \
>        101       comp_name, strlen(comp_name),                                      \
>        102       (char *) klass_name->bytes(), klass_name->utf8_length(),           \
>        103       (char *) name->bytes(), name->utf8_length(),                       \
>        104       (char *) signature->bytes(), signature->utf8_length());            \
>        105   }
>        106
>        107 #define DTRACE_METHOD_COMPILE_END_PROBE(compiler, method,                \
>        108                                         comp_name, success)              \
>        109   {                                                                      \
>        ...                            \
>        113     HOTSPOT_METHOD_COMPILE_END(                                          \
>        114       comp_name, strlen(comp_name),                                      \
>        115       (char *) klass_name->bytes(), klass_name->utf8_length(),           \
>        116       (char *) name->bytes(), name->utf8_length(),                       \
>        117       (char *) signature->bytes(), signature->utf8_length(), (success)); \
>        118   }
>
> where "comp_name" is passed as the first argument to HOTSPOT_METHOD_COMPILE_BEGIN and HOTSPOT_METHOD_COMPILE_END.  Those are "declared" by
>
>         63 HS_DTRACE_PROBE_DECL8(hotspot, method__compile__begin,
>         64   char*, intptr_t, char*, intptr_t, char*, intptr_t, char*, intptr_t);
>         65 HS_DTRACE_PROBE_DECL9(hotspot, method__compile__end,
>         66   char*, intptr_t, char*, intptr_t, char*, intptr_t, char*, intptr_t, bool);
>
> where the first argument is a "char*", not a "const char*" (with a step I'm not showing through the translation of hotspot.d to hotspot.h).  I'm getting compile errors on the uses
>
>      ..../src/share/vm/compiler/compileBroker.cpp: In static member function 'static void CompileBroker::invoke_compiler_on_method(CompileTask*)':
>
>      ..../src/share/vm/compiler/compileBroker.cpp:1789: error: invalid conversion from 'const char*' to 'char*'
>
>      ..../src/share/vm/compiler/compileBroker.cpp:1789: error:   initializing argument 1 of 'void __dtrace_probe$hotspot$method__compile__begin$v1$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74(char*, uintptr_t, char*, uintptr_t, char*, uintptr_t, char*, uintptr_t)'
>
>      ..../src/share/vm/compiler/compileBroker.cpp:1870: error: invalid conversion from 'const char*' to 'char*'
>
>      ..../src/share/vm/compiler/compileBroker.cpp:1870: error:   initializing argument 1 of 'void __dtrace_probe$hotspot$method__compile__end$v1$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74$63686172202a$75696e747074725f74$75696e747074725f74(char*, uintptr_t, char*, uintptr_t, char*, uintptr_t, char*, uintptr_t, uintptr_t)'
>
> How is that code supposed to compile?  This is on MacOSX, and I seem to have DTRACE_ENABLED and USDT2 defined.  The fix seems to be to cast away the const-ness of "comp_name" in the applications of HOTSPOT_METHOD_COMPILE_BEGIN and HOTSPOT_METHOD_COMPILE_END, similar to the way the const-ness is cast away from the other pointer arguments in that call.
>
>              ... peter
>
> [1] http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/d0081bfc425c/src/share/vm/compiler/compileBroker.hpp
> [2] http://hg.openjdk.java.net/jdk8/jdk8/hotspot/file/d0081bfc425c/src/share/vm/compiler/compileBroker.cpp
>