Add stats so we can keep track of x86 rel32 vs register calls (#7142)

* Add stats so we can keep track of x86 rel32 vs register calls

To know if we get that "prime real estate" as Alan put it.

* Fix bug pointed by Alan

3 files changed, 12 insertions, 0 deletions

diff --git a/yjit.rb b/yjit.rb
index 062784f564..0079d8d895 100644
--- a/yjit.rb
+++ b/yjit.rb
@@ -253,6 +253,11 @@ module RubyVM::YJIT
       # Number of failed compiler invocations
       compilation_failure = stats[:compilation_failure]
 
+      if stats[:x86_call_rel32] != 0 || stats[:x86_call_reg] != 0
+        $stderr.puts "x86_call_rel32:        " + ("%10d" % stats[:x86_call_rel32])
+        $stderr.puts "x86_call_reg:          " + ("%10d" % stats[:x86_call_reg])
+      end
+
       $stderr.puts "bindings_allocations:  " + ("%10d" % stats[:binding_allocations])
       $stderr.puts "bindings_set:          " + ("%10d" % stats[:binding_set])
       $stderr.puts "compilation_failure:   " + ("%10d" % compilation_failure) if compilation_failure != 0
diff --git a/yjit/src/asm/x86_64/mod.rs b/yjit/src/asm/x86_64/mod.rs
index 1a0cb9cae7..67bb5d1ffb 100644
--- a/yjit/src/asm/x86_64/mod.rs
+++ b/yjit/src/asm/x86_64/mod.rs
@@ -690,6 +690,8 @@ pub fn call_rel32(cb: &mut CodeBlock, rel32: i32) {
 /// call - Call a pointer, encode with a 32-bit offset if possible
 pub fn call_ptr(cb: &mut CodeBlock, scratch_opnd: X86Opnd, dst_ptr: *const u8) {
     if let X86Opnd::Reg(_scratch_reg) = scratch_opnd {
+        use crate::stats::{incr_counter};
+
         // Pointer to the end of this call instruction
         let end_ptr = cb.get_ptr(cb.write_pos + 5);
 
@@ -698,11 +700,13 @@ pub fn call_ptr(cb: &mut CodeBlock, scratch_opnd: X86Opnd, dst_ptr: *const u8) {
 
         // If the offset fits in 32-bit
         if rel64 >= i32::MIN.into() && rel64 <= i32::MAX.into() {
+            incr_counter!(x86_call_rel32);
             call_rel32(cb, rel64.try_into().unwrap());
             return;
         }
 
         // Move the pointer into the scratch register and call
+        incr_counter!(x86_call_reg);
         mov(cb, scratch_opnd, const_ptr_opnd(dst_ptr));
         call(cb, scratch_opnd);
     } else {
diff --git a/yjit/src/stats.rs b/yjit/src/stats.rs
index 8fc9245364..2145cdf923 100644
--- a/yjit/src/stats.rs
+++ b/yjit/src/stats.rs
@@ -299,6 +299,9 @@ make_counters! {
     exec_mem_non_bump_alloc,
 
     num_gc_obj_refs,
+
+    x86_call_rel32,
+    x86_call_reg,
 }
 
 //===========================================================================