Add volatile XLOADs.

3 files changed, 7 insertions, 3 deletions

diff --git a/lib/dump.lua b/lib/dump.lua
index d79ae8b6..555b4b45 100644
--- a/lib/dump.lua
+++ b/lib/dump.lua
@@ -234,7 +234,7 @@ local litname = {
     t[mode] = s
     return s
   end}),
-  ["XLOAD "] = { [0] = "", "R", "U", "RU", },
+  ["XLOAD "] = { [0] = "", "R", "V", "RV", "U", "RU", "VU", "RVU", },
   ["CONV  "] = setmetatable({}, { __index = function(t, mode)
     local s = irtype[band(mode, 31)]
     s = irtype[band(shr(mode, 5), 31)].."."..s
diff --git a/src/lj_ir.h b/src/lj_ir.h
index d3104017..68901325 100644
--- a/src/lj_ir.h
+++ b/src/lj_ir.h
@@ -206,7 +206,8 @@ IRFLDEF(FLENUM)
 
 /* XLOAD mode, stored in op2. */
 #define IRXLOAD_READONLY        1       /* Load from read-only data. */
-#define IRXLOAD_UNALIGNED       2       /* Unaligned load. */
+#define IRXLOAD_VOLATILE        2       /* Load from volatile data. */
+#define IRXLOAD_UNALIGNED       4       /* Unaligned load. */
 
 /* CONV mode, stored in op2. */
 #define IRCONV_SRCMASK          0x001f  /* Source IRType. */
diff --git a/src/lj_opt_mem.c b/src/lj_opt_mem.c
index 9c22362b..cad85bb7 100644
--- a/src/lj_opt_mem.c
+++ b/src/lj_opt_mem.c
@@ -669,6 +669,8 @@ TRef LJ_FASTCALL lj_opt_fwd_xload(jit_State *J)
 
   if ((fins->op2 & IRXLOAD_READONLY))
     goto cselim;
+  if ((fins->op2 & IRXLOAD_VOLATILE))
+    goto doemit;
 
   /* Search for conflicting stores. */
   ref = J->chain[IR_XSTORE];
@@ -721,7 +723,8 @@ cselim:
     xr = IR(xref);
     goto retry;  /* Retry with the reassociated reference. */
   }
-  return lj_ir_emit(J);
+doemit:
+  return EMITFOLD;
 }
 
 /* XSTORE elimination. */