From 43a3893b0d7d82bfbfd13bf458a5906f755989c9 Mon Sep 17 00:00:00 2001

From: Patrick Galizia <pgalizia.qdt@qualcommdatacenter.com>

Date: Fri, 24 Aug 2018 11:02:15 -0400

Subject: [PATCH 60/72] Fix arm64 register allocation issue for XLOAD.

For the arm64 implementation of asm_xload(), it is possible for

the dest register selected to be the same as one of the source

registers generated in the asm_fusexref() call.  To prevent this,

exclude the dest register from the list of allowed registers for

that call.

Thanks to Javier for guidance as well as his script to replicate

the issue.

---

 src/lj_asm_arm64.h | 3 ++-

 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/lj_asm_arm64.h b/src/lj_asm_arm64.h

index baafa21..045f260 100644

--- a/src/lj_asm_arm64.h

+++ b/src/lj_asm_arm64.h

@@ -1008,7 +1008,8 @@ static void asm_xload(ASMState *as, IRIns *ir)

 {

   Reg dest = ra_dest(as, ir, irt_isfp(ir->t) ? RSET_FPR : RSET_GPR);

   lua_assert(!(ir->op2 & IRXLOAD_UNALIGNED));

-  asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1, RSET_GPR);

+  asm_fusexref(as, asm_fxloadins(ir), dest, ir->op1,

+               rset_exclude(RSET_GPR, dest));

 }

 static void asm_xstore(ASMState *as, IRIns *ir)

-- 

2.20.1