From e99ac1bc2df5c1d138bbc98d35d1a1892144cf2b Mon Sep 17 00:00:00 2001
From: Sameera Deshpande <sameera.deshpande@linaro.org>
Date: Fri, 15 Feb 2019 07:46:16 +0530
Subject: [PATCH 65/72] Add support for FNMADD and FNMSUB.

---
 src/lj_asm_arm64.h | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/lj_asm_arm64.h b/src/lj_asm_arm64.h
index a826687..470e65d 100644
--- a/src/lj_asm_arm64.h
+++ b/src/lj_asm_arm64.h
@@ -344,6 +344,35 @@ static int asm_fusemadd(ASMState *as, IRIns *ir, A64Ins ai, A64Ins air)
   return 0;
 }
 
+/* Fuse FP neg-multiply-add/sub. */
+static int asm_fusenmadd(ASMState *as, IRIns *ir, A64Ins ai, A64Ins air)
+{
+  IRRef ref = ir->op1;
+  IRIns *irn = IR(ref);
+  if (irn->o != IR_ADD && irn->o != IR_SUB)
+    return 0;
+
+  if (!mayfuse(as, ref))
+    return 0;
+
+  IRRef lref = irn->op1, rref = irn->op2;
+  IRIns *irm;
+  if (lref != rref &&
+      ((mayfuse(as, lref) && (irm = IR(lref), irm->o == IR_MUL) &&
+       ra_noreg(irm->r)) ||
+       (mayfuse(as, rref) && (irm = IR(rref), irm->o == IR_MUL) &&
+       (rref = lref, ra_noreg(irm->r))))) {
+    Reg dest = ra_dest(as, ir, RSET_FPR);
+    Reg add = ra_hintalloc(as, rref, dest, RSET_FPR);
+    Reg left = ra_alloc2(as, irm,
+			 rset_exclude(rset_exclude(RSET_FPR, dest), add));
+    Reg right = (left >> 8); left &= 255;
+    emit_dnma(as, (irn->o == IR_ADD ? ai : air), (dest & 31), (left & 31), (right & 31), (add & 31));
+    return 1;
+  }
+  return 0;
+}
+
 /* Fuse BAND + BSHL/BSHR into UBFM. */
 static int asm_fuseandshift(ASMState *as, IRIns *ir)
 {
@@ -1481,7 +1510,8 @@ static void asm_mod(ASMState *as, IRIns *ir)
 static void asm_neg(ASMState *as, IRIns *ir)
 {
   if (irt_isnum(ir->t)) {
-    asm_fpunary(as, ir, A64I_FNEGd);
+    if (!asm_fusenmadd(as, ir, A64I_FNMADDd))
+      asm_fpunary(as, ir, A64I_FNEGd);
     return;
   }
   asm_intneg(as, ir);
-- 
2.20.1