From 91592899275cbb540ca67bbf95b41a2200e4fdbd Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Thu, 21 Sep 2023 02:48:12 +0200
Subject: [PATCH] ARM64: Fix IR_HREF code generation for constant FP keys.

Reported by swarn. Fix for 435d8c63 by Peter Cawley. #1090
---
 src/lj_asm_arm64.h | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/src/lj_asm_arm64.h b/src/lj_asm_arm64.h
index 8673f7df..82f14405 100644
--- a/src/lj_asm_arm64.h
+++ b/src/lj_asm_arm64.h
@@ -787,7 +787,7 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
   int destused = ra_used(ir);
   Reg dest = ra_dest(as, ir, allow);
   Reg tab = ra_alloc1(as, ir->op1, rset_clear(allow, dest));
-  Reg key = 0, tmp = RID_TMP, type = RID_NONE, tkey;
+  Reg tmp = RID_TMP, type = RID_NONE, key, tkey;
   IRRef refkey = ir->op2;
   IRIns *irkey = IR(refkey);
   int isk = irref_isk(refkey);
@@ -797,26 +797,22 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
   MCLabel l_end, l_loop;
   rset_clear(allow, tab);
 
-  /* Allocate registers outside of the loop. */
-  if (irkey->o != IR_KNUM || !(k = emit_isk12((int64_t)ir_knum(irkey)->u64))) {
-    key = ra_alloc1(as, refkey, irt_isnum(kt) ? RSET_FPR : allow);
-    rset_clear(allow, key);
-  }
-  if (!isk) {
-    tkey = ra_scratch(as, allow);
-    rset_clear(allow, tkey);
-  } else if (irt_isnum(kt)) {
-    tkey = key; /* Assumes -0.0 is already canonicalized to +0.0. */
-  } else {
+  /* Allocate register for tkey outside of the loop. */
+  if (isk) {
     int64_t kk;
     if (irt_isaddr(kt)) {
       kk = ((int64_t)irt_toitype(kt) << 47) | irkey[1].tv.u64;
+    } else if (irt_isnum(kt)) {
+      kk = (int64_t)ir_knum(irkey)->u64;
+      /* Assumes -0.0 is already canonicalized to +0.0. */
     } else {
       lj_assertA(irt_ispri(kt) && !irt_isnil(kt), "bad HREF key type");
       kk = ~((int64_t)~irt_toitype(kt) << 47);
     }
-    tkey = ra_allock(as, kk, allow);
-    rset_clear(allow, tkey);
+    k = emit_isk12(kk);
+    tkey = k ? 0 : ra_allock(as, kk, allow);
+  } else {
+    tkey = ra_scratch(as, allow);
   }
 
   /* Key not found in chain: jump to exit (if merged) or load niltv. */
@@ -849,10 +845,13 @@ static void asm_href(ASMState *as, IRIns *ir, IROp merge)
   /* Construct tkey as canonicalized or tagged key. */
   if (!isk) {
     if (irt_isnum(kt)) {
+      key = ra_alloc1(as, refkey, RSET_FPR);
       emit_dnm(as, A64I_CSELx | A64F_CC(CC_EQ), tkey, RID_ZERO, tkey);
+      /* A64I_FMOV_R_D from key to tkey done below. */
     } else {
       lj_assertA(irt_isaddr(kt), "bad HREF key type");
-      type = ra_allock(as, irt_toitype(kt) << 15, allow);
+      key = ra_alloc1(as, refkey, allow);
+      type = ra_allock(as, irt_toitype(kt) << 15, rset_clear(allow, key));
       emit_dnm(as, A64I_ADDx | A64F_SH(A64SH_LSL, 32), tkey, key, type);
     }
   }