mjit_compile.c: use local variables for stack

if catch_except_p is FALSE. If catch_except_p is TRUE, stack values
should be on VM's stack when exception is thrown and the JIT-ed frame
is re-executed by VM's exception handler. If it's FALSE, the JIT-ed
frame won't be re-executed and don't need to keep values on VM's stack.

Using local variables allows us to reduce cfp->sp motion. Moving cfp->sp
is needed only for insns whose handles_frame? is false. So it improves
performance.

_mjit_compile_insn.erb: Prepare `stack_size` variable for GET_SP,
STACK_ADDR_FROM_TOP, TOPN macros. Share pc and sp motion partial view.
Use cancel handler created in mjit_compile.c.

_mjit_compile_send.erb: ditto. Also, when iseq->body->catch_except_p is
TRUE, this stops to call mjit_exec directly. I described the reason in
vm_insnhelper.h's comment for EXEC_EC_CFP.

_mjit_compile_pc_and_sp.erb: Shared logic for moving sp and pc. As you
can see from thsi file, when status->local_stack_p is TRUE and
insn.handles_frame? is false, moving sp is skipped. But if
insn.handles_frame? is true, values should be rolled back to VM's stack.
common.mk: add dependency for the file

_mjit_compile_insn_body.erb: Set sp value before canceling JIT on
DISPATCH_ORIGINAL_INSN. Replace GET_SP, STACK_ADDR_FROM_TOP, TOPN macros
for the case ocal_stack_p is TRUE and insn.handles_frame? is false.
In that case, values are not available on VM's stack and those macros
should be replaced.

mjit_compile.inc.erb: updated comments of macros which are supported by
JIT compiler. All references to `cfp->sp` should be replaced and thus
INC_SP, SET_SV, PUSH are no longer supported for now, because they are
not used now.

vm_exec.h: moved EXEC_EC_CFP definition to vm_insnhelper.h because it's
tighly coupled to CALL_METHOD.

vm_insnhelper.h: Have revised EXEC_EC_CFP definition moved from vm_exec.h.
Now it triggers mjit_exec for VM, and has the guard for catch_except_p
on JIT-ed code. See comments for details. CALL_METHOD delegates
triggering mjit_exec to EXEC_EC_CFP.

insns.def: Stopped using EXEC_EC_CFP for the case we don't want to
trigger mjit_exec. Those insns (defineclass, opt_call_c_function) are
not supported by JIT and it's safe to use RESTORE_REGS(), NEXT_INSN().
expandarray is changed to pass GET_SP() to replace the macro in
_mjit_compile_insn_body.erb.

vm_insnhelper.c: change to take sp for the above reason.

[close https://github.com/ruby/ruby/pull/1828]

This patch resurrects the performance which was attached in
[Feature #14235].

* Benchmark

Optcarrot (with configuration for benchmark_driver.gem)
https://github.com/benchmark-driver/optcarrot

$ benchmark-driver benchmark.yml --verbose 1 --rbenv 'before;before+JIT::before,--jit;after;after+JIT::after,--jit' --repeat-count 10
before: ruby 2.6.0dev (2018-03-04 trunk 62652) [x86_64-linux]
before+JIT: ruby 2.6.0dev (2018-03-04 trunk 62652) +JIT [x86_64-linux]
after: ruby 2.6.0dev (2018-03-04 local-variable.. 62652) [x86_64-linux]
last_commit=mjit_compile.c: use local variables for stack
after+JIT: ruby 2.6.0dev (2018-03-04 local-variable.. 62652) +JIT [x86_64-linux]
last_commit=mjit_compile.c: use local variables for stack
Calculating -------------------------------------
                         before  before+JIT       after   after+JIT
           optcarrot     53.552      59.680      53.697      63.358 fps

Comparison:
                        optcarrot
           after+JIT:        63.4 fps
          before+JIT:        59.7 fps - 1.06x  slower
               after:        53.7 fps - 1.18x  slower
              before:        53.6 fps - 1.18x  slower

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62655 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 25 insertions, 1 deletions

diff --git a/mjit_compile.c b/mjit_compile.c
index eaf7c832b2..5bf14a1388 100644
--- a/mjit_compile.c
+++ b/mjit_compile.c
@@ -20,6 +20,9 @@
 struct compile_status {
     int success; /* has TRUE if compilation has had no issue */
     int *compiled_for_pos; /* compiled_for_pos[pos] has TRUE if the pos is compiled */
+    /* If TRUE, JIT-ed code will use local variables to store pushed values instead of
+       using VM's stack and moving stack pointer. */
+    int local_stack_p;
 };
 
 /* Storage to keep data which is consistent in each conditional branch.
@@ -151,6 +154,20 @@ compile_insns(FILE *f, const struct rb_iseq_constant_body *body, unsigned int st
     }
 }
 
+/* Print the block to cancel JIT execution. */
+static void
+compile_cancel_handler(FILE *f, const struct rb_iseq_constant_body *body, struct compile_status *status)
+{
+    unsigned int i;
+    fprintf(f, "\ncancel:\n");
+    if (status->local_stack_p) {
+        for (i = 0; i < body->stack_max; i++) {
+            fprintf(f, "    *((VALUE *)reg_cfp->bp + %d) = stack[%d];\n", i + 1, i);
+        }
+    }
+    fprintf(f, "    return Qundef;\n");
+}
+
 /* Compile ISeq to C code in F.  It returns 1 if it succeeds to compile. */
 int
 mjit_compile(FILE *f, const struct rb_iseq_constant_body *body, const char *funcname)
@@ -158,12 +175,18 @@ mjit_compile(FILE *f, const struct rb_iseq_constant_body *body, const char *func
     struct compile_status status;
     status.success = TRUE;
     status.compiled_for_pos = ZALLOC_N(int, body->iseq_size);
+    status.local_stack_p = !body->catch_except_p;
 
 #ifdef _WIN32
     fprintf(f, "__declspec(dllexport)\n");
 #endif
     fprintf(f, "VALUE\n%s(rb_execution_context_t *ec, rb_control_frame_t *reg_cfp)\n{\n", funcname);
-    fprintf(f, "    VALUE *stack = reg_cfp->sp;\n");
+    if (status.local_stack_p) {
+        fprintf(f, "    VALUE stack[%d];\n", body->stack_max);
+    }
+    else {
+        fprintf(f, "    VALUE *stack = reg_cfp->sp;\n");
+    }
     fprintf(f, "    static const VALUE *const original_body_iseq = (VALUE *)0x%"PRIxVALUE";\n",
             (VALUE)body->iseq_encoded);
 
@@ -186,6 +209,7 @@ mjit_compile(FILE *f, const struct rb_iseq_constant_body *body, const char *func
     fprintf(f, "    }\n");
 
     compile_insns(f, body, 0, 0, &status);
+    compile_cancel_handler(f, body, &status);
     fprintf(f, "\n} /* end of %s */\n", funcname);
 
     xfree(status.compiled_for_pos);