From 01eb83dcfe30368633f18161a85414daf3fc407c Mon Sep 17 00:00:00 2001
From: Dibyendu Majumdar <mobile@majumdar.org.uk>
Date: Sun, 16 Dec 2018 12:41:21 +0000
Subject: [PATCH] issue #161 avoid taking address of math functions in the fast
 call scenario, instead assign unique codes to functions that may be inlined

---
 include/lua.h               |  4 +++-
 ravi-tests/ravi_tests1.ravi | 10 ++++++++++
 src/ldo.c                   | 19 +++++++++++++++----
 src/ravijit.cpp             |  4 ++--
 4 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/include/lua.h b/include/lua.h
index bd3eaa7..0e98d05 100644
--- a/include/lua.h
+++ b/include/lua.h
@@ -549,7 +549,9 @@ struct lua_Debug {
 
 LUA_API void  (ravi_pushcfastcall)(lua_State *L, void *ptr, int tag);
 
-#define RAVI_TFCF_D_D 1
+#define RAVI_TFCF_EXP 1
+#define RAVI_TFCF_LOG 2
+#define RAVI_TFCF_D_D 3
 
 /* Create an integer array (specialization of Lua table)
  * of given size and initialize array with supplied initial value
diff --git a/ravi-tests/ravi_tests1.ravi b/ravi-tests/ravi_tests1.ravi
index 36719e9..00e0ce8 100644
--- a/ravi-tests/ravi_tests1.ravi
+++ b/ravi-tests/ravi_tests1.ravi
@@ -1695,6 +1695,16 @@ check(x, 'NEW_IARRAY', 'LOADK', 'SETLIST', 'TEST',
   'RETURN', 'RETURN')
 print 'Test 74 OK'
 
+function x()
+  assert(math.exp(2) == ravi.exp(2))
+  assert(math.log(2) == ravi.ln(2))
+  assert(math.exp(math.log(2)) == ravi.exp(ravi.ln(2)))
+end
+x()
+compile(x)
+x()
+print 'Test 75 OK'
+
 for k,v in pairs(opcodes_coverage)
 do
   print(k, v)
diff --git a/src/ldo.c b/src/ldo.c
index 1c5147c..51fbd76 100644
--- a/src/ldo.c
+++ b/src/ldo.c
@@ -13,6 +13,7 @@
 #include <setjmp.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 
 #include "lua.h"
 
@@ -514,10 +515,12 @@ int luaD_precall (lua_State *L, StkId func, int nresults, int op_call) {
       return 0;
     }
     case RAVI_TFCF: {
-      int tt = rttype(func);
       int nargs = L->top - func - 1;
-      int sig = tt >> 8;
+      int tt = rttype(func);
+      int sig = tt >> 8; /* Extract the function signature*/
       switch (sig) {
+        case RAVI_TFCF_LOG:
+        case RAVI_TFCF_EXP:
         case RAVI_TFCF_D_D: {
           if (nargs == 1) {
             TValue *arg1 = func + 1;
@@ -529,8 +532,16 @@ int luaD_precall (lua_State *L, StkId func, int nresults, int op_call) {
             else
               nargs = 0;
             if (nargs) {
-              double (*f)(double) = fcfvalue(func);
-              double v = f(arg);
+              double v;
+              switch (sig) {
+                case RAVI_TFCF_EXP: v = exp(arg); break;
+                case RAVI_TFCF_LOG: v = log(arg); break;
+                default: {
+                  double(*f)(double) = fcfvalue(func);
+                  double v = f(arg);
+                  break;
+                }
+              }
               setfltvalue(func, v);
               L->top = func + 1; /* top points after the last result */
               return 1;
diff --git a/src/ravijit.cpp b/src/ravijit.cpp
index 93b3e3d..6fbbc99 100644
--- a/src/ravijit.cpp
+++ b/src/ravijit.cpp
@@ -272,9 +272,9 @@ static const luaL_Reg ravilib[] = {{"iscompiled", ravi_is_compiled},
 LUAMOD_API int raviopen_llvmjit(lua_State *L) {
   luaL_newlib(L, ravilib);
   /* faster calls some maths functions */
-  ravi_pushcfastcall(L, (void *)exp, RAVI_TFCF_D_D);
+  ravi_pushcfastcall(L, NULL, RAVI_TFCF_EXP);
   lua_setfield(L, -2, "exp");
-  ravi_pushcfastcall(L, (void *)log, RAVI_TFCF_D_D);
+  ravi_pushcfastcall(L, NULL, RAVI_TFCF_LOG);
   lua_setfield(L, -2, "ln");
   return 1;
 }