Implemented mechanism for rel32 call

3 files changed, 37 insertions, 3 deletions

diff --git a/ujit_asm.c b/ujit_asm.c
index c99ad37d66..0b833445b2 100644
--- a/ujit_asm.c
+++ b/ujit_asm.c
@@ -758,7 +758,7 @@ void cb_write_jcc_ptr(codeblock_t* cb, const char* mnem, uint8_t op0, uint8_t op
         cb_write_byte(cb, op0);
     cb_write_byte(cb, op1);
 
-    // Pointer to the end of this jump
+    // Pointer to the end of this jump instruction
     uint8_t* end_ptr = &cb->mem_block[cb->write_pos] + 4;
 
     // Compute the jump offset
@@ -822,6 +822,40 @@ void and(codeblock_t* cb, x86opnd_t opnd0, x86opnd_t opnd1)
     );
 }
 
+// call - Call to a pointer with a 32-bit displacement offset
+void call_rel32(codeblock_t* cb, int32_t rel32)
+{
+    //cb.writeASM("call", rel32);
+
+    // Write the opcode
+    cb_write_byte(cb, 0xE8);
+
+    // Write the relative 32-bit jump offset
+    cb_write_int(cb, (int32_t)rel32, 32);
+}
+
+// call - Call a pointer, encode with a 32-bit offset if possible
+void call_ptr(codeblock_t* cb, x86opnd_t scratch_reg, uint8_t* dst_ptr)
+{
+    assert (scratch_reg.type == OPND_REG);
+
+    // Pointer to the end of this call instruction
+    uint8_t* end_ptr = &cb->mem_block[cb->write_pos] + 5;
+
+    // Compute the jump offset
+    int64_t rel64 = (int64_t)(dst_ptr - end_ptr);
+
+    // If the offset fits in 32-bit
+    if (rel64 >= -2147483648 && rel64 <= 2147483647)
+    {
+        return call_rel32(cb, (int32_t)rel64);
+    }
+
+    // Move the pointer into the scratch register and call
+    mov(cb, scratch_reg, const_ptr_opnd(dst_ptr));
+    call(cb, scratch_reg);
+}
+
 /// call - Call to label with 32-bit offset
 void call_label(codeblock_t* cb, size_t label_idx)
 {
diff --git a/ujit_asm.h b/ujit_asm.h
index 6d6b18b0a9..ca5e8884ce 100644
--- a/ujit_asm.h
+++ b/ujit_asm.h
@@ -254,6 +254,7 @@ void cb_link_labels(codeblock_t* cb);
 // Encode individual instructions into a code block
 void add(codeblock_t* cb, x86opnd_t opnd0, x86opnd_t opnd1);
 void and(codeblock_t* cb, x86opnd_t opnd0, x86opnd_t opnd1);
+void call_ptr(codeblock_t* cb, x86opnd_t scratch_reg, uint8_t* dst_ptr);
 void call_label(codeblock_t* cb, size_t label_idx);
 void call(codeblock_t* cb, x86opnd_t opnd);
 void cmova(codeblock_t* cb, x86opnd_t dst, x86opnd_t src);
diff --git a/ujit_compile.c b/ujit_compile.c
index dcf4b672c9..678f84c977 100644
--- a/ujit_compile.c
+++ b/ujit_compile.c
@@ -668,8 +668,7 @@ gen_opt_send_without_block(codeblock_t* cb, codeblock_t* ocb, ctx_t* ctx)
 
     // Call the C function
     // VALUE ret = (cfunc->func)(recv, argv[0], argv[1]);
-    mov(cb, REG0, const_ptr_opnd(cfunc->func));
-    call(cb, REG0);
+    call_ptr(cb, REG0, cfunc->func);
 
     //print_str(cb, "after C call");