Add IR_FLOAD with REF_NIL for field loads from GG_State.

Contributed by Peter Cawley.

src/Makefile.dep

@@ -162,8 +162,8 @@ lj_opt_narrow.o: lj_opt_narrow.c lj_obj.h lua.h luaconf.h lj_def.h \
 lj_opt_sink.o: lj_opt_sink.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_ir.h lj_jit.h lj_iropt.h lj_target.h lj_target_*.h
 lj_opt_split.o: lj_opt_split.c lj_obj.h lua.h luaconf.h lj_def.h \
- lj_arch.h lj_err.h lj_errmsg.h lj_buf.h lj_gc.h lj_str.h lj_ir.h \
+ lj_arch.h lj_err.h lj_errmsg.h lj_buf.h lj_gc.h lj_str.h lj_dispatch.h \
- lj_jit.h lj_ircall.h lj_iropt.h lj_vm.h
+ lj_bc.h lj_jit.h lj_ir.h lj_ircall.h lj_iropt.h lj_vm.h
 lj_parse.o: lj_parse.c lj_obj.h lua.h luaconf.h lj_def.h lj_arch.h \
  lj_gc.h lj_err.h lj_errmsg.h lj_debug.h lj_buf.h lj_str.h lj_tab.h \
  lj_func.h lj_state.h lj_bc.h lj_ctype.h lj_strfmt.h lj_lex.h lj_parse.h \

src/lj_asm_arm.h

@@ -997,6 +997,9 @@ static ARMIns asm_fxstoreins(IRIns *ir)
 
 static void asm_fload(ASMState *as, IRIns *ir)
 {
+  if (ir->op1 == REF_NIL) {
+    lua_assert(!ra_used(ir));  /* We can end up here if DCE is turned off. */
+  } else {
     Reg dest = ra_dest(as, ir, RSET_GPR);
     Reg idx = ra_alloc1(as, ir->op1, RSET_GPR);
     ARMIns ai = asm_fxloadins(ir);
@@ -1013,6 +1016,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
       emit_lso(as, ai, dest, idx, ofs);
     else
       emit_lsox(as, ai, dest, idx, ofs);
+  }
 }
 
 static void asm_fstore(ASMState *as, IRIns *ir)

src/lj_asm_mips.h

@@ -896,9 +896,14 @@ static MIPSIns asm_fxstoreins(IRIns *ir)
 static void asm_fload(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
-  Reg idx = ra_alloc1(as, ir->op1, RSET_GPR);
   MIPSIns mi = asm_fxloadins(ir);
+  Reg idx;
   int32_t ofs;
+  if (ir->op1 == REF_NIL) {
+    idx = RID_JGL;
+    ofs = ir->op2 - 32768;
+  } else {
+    idx = ra_alloc1(as, ir->op1, RSET_GPR);
     if (ir->op2 == IRFL_TAB_ARRAY) {
       ofs = asm_fuseabase(as, ir->op1);
       if (ofs) {  /* Turn the t->array load into an add for colocated arrays. */
@@ -907,6 +912,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
       }
     }
     ofs = field_ofs[ir->op2];
+  }
   lua_assert(!irt_isfp(ir->t));
   emit_tsi(as, mi, dest, idx, ofs);
 }

src/lj_asm_ppc.h

@@ -804,9 +804,14 @@ static PPCIns asm_fxstoreins(IRIns *ir)
 static void asm_fload(ASMState *as, IRIns *ir)
 {
   Reg dest = ra_dest(as, ir, RSET_GPR);
-  Reg idx = ra_alloc1(as, ir->op1, RSET_GPR);
   PPCIns pi = asm_fxloadins(ir);
+  Reg idx;
   int32_t ofs;
+  if (ir->op1 == REF_NIL) {
+    idx = RID_JGL;
+    ofs = ir->op2 - 32768;
+  } else {
+    idx = ra_alloc1(as, ir->op1, RSET_GPR);
     if (ir->op2 == IRFL_TAB_ARRAY) {
       ofs = asm_fuseabase(as, ir->op1);
       if (ofs) {  /* Turn the t->array load into an add for colocated arrays. */
@@ -815,6 +820,7 @@ static void asm_fload(ASMState *as, IRIns *ir)
       }
     }
     ofs = field_ofs[ir->op2];
+  }
   lua_assert(!irt_isi8(ir->t));
   emit_tai(as, pi, dest, idx, ofs);
 }

src/lj_asm_x86.h

@@ -205,8 +205,13 @@ static void asm_fuseahuref(ASMState *as, IRRef ref, RegSet allow)
 static void asm_fusefref(ASMState *as, IRIns *ir, RegSet allow)
 {
   lua_assert(ir->o == IR_FLOAD || ir->o == IR_FREF);
-  as->mrm.ofs = field_ofs[ir->op2];
   as->mrm.idx = RID_NONE;
+  if (ir->op1 == REF_NIL) {
+    as->mrm.ofs = (int32_t)ir->op2 + ptr2addr(J2GG(as->J));
+    as->mrm.base = RID_NONE;
+    return;
+  }
+  as->mrm.ofs = field_ofs[ir->op2];
   if (irref_isk(ir->op1)) {
     as->mrm.ofs += IR(ir->op1)->i;
     as->mrm.base = RID_NONE;
@@ -369,6 +374,10 @@ static Reg asm_fuseload(ASMState *as, IRRef ref, RegSet allow)
       return RID_MRM;
     }
   }
+  if (ir->o == IR_FLOAD && ir->op1 == REF_NIL) {
+    asm_fusefref(as, ir, RSET_EMPTY);
+    return RID_MRM;
+  }
   if (!(as->freeset & allow) && !irref_isk(ref) &&
       (allow == RSET_EMPTY || ra_hasspill(ir->s) || iscrossref(as, ref)))
     goto fusespill;

src/lj_ir.c

@@ -145,6 +145,14 @@ TRef lj_ir_call(jit_State *J, IRCallID id, ...)
   return emitir(CCI_OPTYPE(ci), tr, id);
 }
 
+/* Load field of type t from GG_State + offset. */
+LJ_FUNC TRef lj_ir_ggfload(jit_State *J, IRType t, uintptr_t ofs)
+{
+  lua_assert(ofs >= IRFL__MAX && ofs < REF_BIAS);
+  lj_ir_set(J, IRT(IR_FLOAD, t), REF_NIL, ofs);
+  return lj_opt_fold(J);
+}
+
 /* -- Interning of constants ---------------------------------------------- */
 
 /*

src/lj_iropt.h

@@ -36,6 +36,8 @@ static LJ_AINLINE IRRef lj_ir_nextins(jit_State *J)
   return ref;
 }
 
+LJ_FUNC TRef lj_ir_ggfload(jit_State *J, IRType t, uintptr_t ofs);
+
 /* Interning of constants. */
 LJ_FUNC TRef LJ_FASTCALL lj_ir_kint(jit_State *J, int32_t k);
 LJ_FUNC void lj_ir_k64_freeall(jit_State *J);

src/lj_opt_split.c

@@ -12,6 +12,7 @@
 
 #include "lj_err.h"
 #include "lj_buf.h"
+#include "lj_dispatch.h"
 #include "lj_ir.h"
 #include "lj_jit.h"
 #include "lj_ircall.h"
@@ -448,6 +449,11 @@ static void split_ir(jit_State *J)
       case IR_STRTO:
 	hi = split_emit(J, IRT(IR_HIOP, IRT_SOFTFP), nref, nref);
 	break;
+      case IR_FLOAD:
+	lua_assert(ir->op1 == REF_NIL);
+	hi = lj_ir_kint(J, *(int32_t*)((char*)J2GG(J) + ir->op2 + LJ_LE*4));
+	nir->op2 += LJ_BE*4;
+	break;
       case IR_XLOAD: {
 	IRIns inslo = *nir;  /* Save/undo the emit of the lo XLOAD. */
 	J->cur.nins--;