Increase default YJIT call threshold to 10. Add exec mem size arg. (#52)

README.md

@@ -82,11 +82,12 @@ The machine code generated for a given method can be printed by adding `puts YJI
 
 YJIT supports all command-line options supported by upstream CRuby, but also adds a few YJIT-specific options:
 
- - `--disable-yjit`: turn off YJIT (enabled by default)
- - `--yjit-stats`: produce statistics after the execution of a program (must compile with `cppflags=-DRUBY_DEBUG` to use this)
- - `--yjit-call-threshold=N`: number of calls after which YJIT begins to compile a function (default 2)
- - `--yjit-version-limit=N`: maximum number of versions to generate per basic block (default 4)
- - `--yjit-greedy-versioning`: greedy versioning mode (disabled by default, may increase code size)
+- `--disable-yjit`: turn off YJIT (enabled by default)
+- `--yjit-stats`: produce statistics after the execution of a program (must compile with `cppflags=-DRUBY_DEBUG` to use this)
+- `--yjit-exec-mem-size=N`: size of the executable memory block to allocate (default 256 MiB)
+- `--yjit-call-threshold=N`: number of calls after which YJIT begins to compile a function (default 2)
+- `--yjit-version-limit=N`: maximum number of versions to generate per basic block (default 4)
+- `--yjit-greedy-versioning`: greedy versioning mode (disabled by default, may increase code size)
 
 ### Benchmarking
 
@@ -142,7 +143,7 @@ The core of CRuby's interpreter logic is found in:
 - `vm_insnshelper.c`: logic used by Ruby's bytecode instructions
 - `vm_exec.c`: Ruby interpreter loop
 
-### Coding & Debugging Protips 
+### Coding & Debugging Protips
 
 There are 3 test suites:
 - `make btest` (see `/bootstraptest`)

ruby.c

@@ -1036,7 +1036,10 @@ setup_yjit_options(const char *s, struct rb_yjit_options *yjit_opt)
     if (*s != '-') return;
     const size_t l = strlen(++s);
 
-    if (opt_match_arg(s, l, "call-threshold")) {
+    if (opt_match_arg(s, l, "exec-mem-size")) {
+        yjit_opt->exec_mem_size = atoi(s + 1);
+    }
+    else if (opt_match_arg(s, l, "call-threshold")) {
         yjit_opt->call_threshold = atoi(s + 1);
     }
     else if (opt_match_arg(s, l, "version-limit")) {

yjit.h

@@ -33,6 +33,9 @@ struct rb_yjit_options {
     // Enable compilation with YJIT
     bool yjit_enabled;
 
+    // Size of the executable memory block to allocate in MiB
+    unsigned exec_mem_size;
+
     // Number of method calls after which to start generating code
     // Threshold==1 means compile on first execution
     unsigned call_threshold;

yjit_codegen.c

@@ -2792,7 +2792,7 @@ void
 yjit_init_codegen(void)
 {
     // Initialize the code blocks
-    uint32_t mem_size = 128 * 1024 * 1024;
+    uint32_t mem_size = rb_yjit_opts.exec_mem_size * 1024 * 1024;
     uint8_t *mem_block = alloc_exec_mem(mem_size);
 
     cb = █

yjit_iface.c

@@ -1048,9 +1048,12 @@ rb_yjit_init(struct rb_yjit_options *options)
     rb_yjit_opts = *options;
     rb_yjit_opts.yjit_enabled = true;
 
-    // Normalize command-line options
+    // Normalize command-line options to default values
+    if (rb_yjit_opts.exec_mem_size < 1) {
+        rb_yjit_opts.exec_mem_size = 256;
+    }
     if (rb_yjit_opts.call_threshold < 1) {
-        rb_yjit_opts.call_threshold = 2;
+        rb_yjit_opts.call_threshold = 10;
     }
     if (rb_yjit_opts.version_limit < 1) {
         rb_yjit_opts.version_limit = 4;