From de6b1a11dd1a3349179084578c5d533be1c30234 Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Mon, 12 Oct 2020 15:40:28 +0200
Subject: [PATCH] Ensure full init of IR_NOP instructions.

---
 src/lj_asm.c     |  2 +-
 src/lj_ir.h      |  8 ++++++++
 src/lj_opt_dce.c |  5 +----
 src/lj_opt_mem.c | 25 +++++--------------------
 4 files changed, 15 insertions(+), 25 deletions(-)

diff --git a/src/lj_asm.c b/src/lj_asm.c
index 9b17421e..60be4337 100644
--- a/src/lj_asm.c
+++ b/src/lj_asm.c
@@ -1833,7 +1833,7 @@ void lj_asm_trace(jit_State *J, GCtrace *T)
 
   /* Ensure an initialized instruction beyond the last one for HIOP checks. */
   J->cur.nins = lj_ir_nextins(J);
-  J->cur.ir[J->cur.nins].o = IR_NOP;
+  lj_ir_nop(&J->cur.ir[J->cur.nins]);
 
   /* Setup initial state. Copy some fields to reduce indirections. */
   as->J = J;
diff --git a/src/lj_ir.h b/src/lj_ir.h
index 3a154a05..ac51dc79 100644
--- a/src/lj_ir.h
+++ b/src/lj_ir.h
@@ -548,4 +548,12 @@ static LJ_AINLINE int ir_sideeff(IRIns *ir)
 
 LJ_STATIC_ASSERT((int)IRT_GUARD == (int)IRM_W);
 
+/* Replace IR instruction with NOP. */
+static LJ_AINLINE void lj_ir_nop(IRIns *ir)
+{
+  ir->ot = IRT(IR_NOP, IRT_NIL);
+  ir->op1 = ir->op2 = 0;
+  ir->prev = 0;
+}
+
 #endif
diff --git a/src/lj_opt_dce.c b/src/lj_opt_dce.c
index a1df91dd..31e5badd 100644
--- a/src/lj_opt_dce.c
+++ b/src/lj_opt_dce.c
@@ -47,10 +47,7 @@ static void dce_propagate(jit_State *J)
       pchain[ir->o] = &ir->prev;
     } else if (!ir_sideeff(ir)) {
       *pchain[ir->o] = ir->prev;  /* Reroute original instruction chain. */
-      ir->t.irt = IRT_NIL;
-      ir->o = IR_NOP;  /* Replace instruction with NOP. */
-      ir->op1 = ir->op2 = 0;
-      ir->prev = 0;
+      lj_ir_nop(ir);
       continue;
     }
     if (ir->op1 >= REF_FIRST) irt_setmark(IR(ir->op1)->t);
diff --git a/src/lj_opt_mem.c b/src/lj_opt_mem.c
index 281f29ad..5659a056 100644
--- a/src/lj_opt_mem.c
+++ b/src/lj_opt_mem.c
@@ -352,10 +352,7 @@ TRef LJ_FASTCALL lj_opt_dse_ahstore(jit_State *J)
 	    goto doemit;  /* No elimination possible. */
 	/* Remove redundant store from chain and replace with NOP. */
 	*refp = store->prev;
-	store->o = IR_NOP;
-	store->t.irt = IRT_NIL;
-	store->op1 = store->op2 = 0;
-	store->prev = 0;
+	lj_ir_nop(store);
 	/* Now emit the new store instead. */
       }
       goto doemit;
@@ -456,10 +453,7 @@ TRef LJ_FASTCALL lj_opt_dse_ustore(jit_State *J)
 	    goto doemit;  /* No elimination possible. */
 	/* Remove redundant store from chain and replace with NOP. */
 	*refp = store->prev;
-	store->o = IR_NOP;
-	store->t.irt = IRT_NIL;
-	store->op1 = store->op2 = 0;
-	store->prev = 0;
+	lj_ir_nop(store);
 	if (ref+1 < J->cur.nins &&
 	    store[1].o == IR_OBAR && store[1].op1 == xref) {
 	  IRRef1 *bp = &J->chain[IR_OBAR];
@@ -468,10 +462,7 @@ TRef LJ_FASTCALL lj_opt_dse_ustore(jit_State *J)
 	    bp = &obar->prev;
 	  /* Remove OBAR, too. */
 	  *bp = obar->prev;
-	  obar->o = IR_NOP;
-	  obar->t.irt = IRT_NIL;
-	  obar->op1 = obar->op2 = 0;
-	  obar->prev = 0;
+	  lj_ir_nop(obar);
 	}
 	/* Now emit the new store instead. */
       }
@@ -562,10 +553,7 @@ TRef LJ_FASTCALL lj_opt_dse_fstore(jit_State *J)
 	    goto doemit;  /* No elimination possible. */
 	/* Remove redundant store from chain and replace with NOP. */
 	*refp = store->prev;
-	store->o = IR_NOP;
-	store->t.irt = IRT_NIL;
-	store->op1 = store->op2 = 0;
-	store->prev = 0;
+	lj_ir_nop(store);
 	/* Now emit the new store instead. */
       }
       goto doemit;
@@ -816,10 +804,7 @@ TRef LJ_FASTCALL lj_opt_dse_xstore(jit_State *J)
 	    goto doemit;  /* No elimination possible. */
 	/* Remove redundant store from chain and replace with NOP. */
 	*refp = store->prev;
-	store->o = IR_NOP;
-	store->t.irt = IRT_NIL;
-	store->op1 = store->op2 = 0;
-	store->prev = 0;
+	lj_ir_nop(store);
 	/* Now emit the new store instead. */
       }
       goto doemit;