Yeah, this actually works!

1 files changed, 33 insertions, 1 deletions

diff --git a/iseq.c b/iseq.c
index 6928a711ed..67af3371dd 100644
--- a/iseq.c
+++ b/iseq.c
@@ -42,6 +42,10 @@
 #include "builtin.h"
 #include "insns.inc"
 #include "insns_info.inc"
+#include <sys/mman.h>
+#include "ujit_examples.h"
+
+uint8_t *native_pop_code; // TODO: hack. see addr2insn
 
 VALUE rb_cISeq;
 static VALUE iseqw_new(const rb_iseq_t *iseq);
@@ -3205,6 +3209,22 @@ rb_vm_encoded_insn_data_table_init(void)
         st_add_direct(encoded_insn_data, key1, (st_data_t)&insn_data[insn]);
         st_add_direct(encoded_insn_data, key2, (st_data_t)&insn_data[insn]);
     }
+
+    native_pop_code = mmap(0, 4096, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, 0, 0);
+    if (native_pop_code == MAP_FAILED) rb_bug("mmap failed");
+    uint8_t *head = native_pop_code;
+    memcpy(head, ujit_pre_call_bytes, sizeof(ujit_pre_call_bytes));
+    head += sizeof(ujit_pre_call_bytes);
+    const uint8_t handmade_pop[] = {           // TODO assmeble this from a separate file
+       0x48, 0x83, 0x6f, 0x08, 0x08,         //	subq	$8, 8(%rdi)
+       0x48, 0x83, 0xc6, 0x08,               //	addq	$8, %rsi
+       0x48, 0x89, 0x37,                     //	movq	%rsi, (%rdi)
+       0x48, 0x89, 0xf0                      //	movq	%rsi, %rax
+    };
+    memcpy(head, handmade_pop, sizeof(handmade_pop));
+    head += sizeof(handmade_pop);
+    memcpy(head, ujit_post_call_bytes, sizeof(ujit_post_call_bytes));
+    // TODO this is small enough to fit in the page we allocated but that can change
 }
 
 int
@@ -3218,6 +3238,12 @@ rb_vm_insn_addr2insn(const void *addr)
         return (int)e->insn;
     }
 
+    // TODO this is a hack. The proper way to do this is to refactor this so that it takes
+    // the iseq body.
+    if (addr && addr == native_pop_code) {
+        return BIN(pop);
+    }
+
     rb_bug("rb_vm_insn_addr2insn: invalid insn address: %p", addr);
 }
 
@@ -3248,6 +3274,12 @@ encoded_iseq_trace_instrument(VALUE *iseq_encoded_insn, rb_event_flag_t turnon,
         return e->insn_len;
     }
 
+    // TODO this is a hack. The proper way to do this is to refactor this so that it takes
+    // the iseq body.
+    if (key && (uint8_t *)key == native_pop_code) {
+        return insn_len(BIN(pop));
+    }
+
     rb_bug("trace_instrument: invalid insn address: %p", (void *)*iseq_encoded_insn);
 }
 
@@ -3456,7 +3488,7 @@ trace_set_i(void *vstart, void *vend, size_t stride, void *data)
 }
 
 VALUE *
-rb_ujit_empty_func(rb_control_frame_t *cfp)
+rb_ujit_empty_func(rb_control_frame_t *cfp, const VALUE *pc)
 {
     // okay, not really empty, so maybe think of another name.
     // it's put in this file instead of say, compile.c to dodge long C compile time.