Refactor table traversal.

Sponsored by OpenResty Inc.

1 files changed, 22 insertions, 40 deletions

diff --git a/src/vm_x86.dasc b/src/vm_x86.dasc
index 81b899fa..718cb8f0 100644
--- a/src/vm_x86.dasc
+++ b/src/vm_x86.dasc
@@ -1673,55 +1673,35 @@ static void build_subroutines(BuildCtx *ctx)
   |  je >2                              // Missing 2nd arg?
   |1:
   |  cmp dword [BASE+4], LJ_TTAB;  jne ->fff_fallback
-  |  mov L:RB, SAVE_L
-  |  mov L:RB->base, BASE               // Add frame since C call can throw.
-  |  mov L:RB->top, BASE                // Dummy frame length is ok.
   |  mov PC, [BASE-4]
+  |  mov RB, BASE                       // Save BASE.
   |.if X64WIN
-  |  lea CARG3d, [BASE+8]
-  |  mov CARG2d, [BASE]                 // Caveat: CARG2d == BASE.
-  |  mov CARG1d, L:RB
+  |  mov CARG1d, [BASE]
+  |  lea CARG3d, [BASE-8]
+  |  lea CARG2d, [BASE+8]               // Caveat: CARG2d == BASE.
   |.elif X64
-  |  mov CARG2d, [BASE]
-  |  lea CARG3d, [BASE+8]               // Caveat: CARG3d == BASE.
-  |  mov CARG1d, L:RB
+  |  mov CARG1d, [BASE]
+  |  lea CARG2d, [BASE+8]
+  |  lea CARG3d, [BASE-8]               // Caveat: CARG3d == BASE.
   |.else
   |  mov TAB:RD, [BASE]
-  |  mov ARG2, TAB:RD
-  |  mov ARG1, L:RB
+  |  mov ARG1, TAB:RD
   |  add BASE, 8
+  |  mov ARG2, BASE
+  |  sub BASE, 8+8
   |  mov ARG3, BASE
   |.endif
-  |  mov SAVE_PC, PC                    // Needed for ITERN fallback.
-  |  call extern lj_tab_next    // (lua_State *L, GCtab *t, TValue *key)
-  |  // Flag returned in eax (RD).
-  |  mov BASE, L:RB->base
-  |  test RD, RD;  jz >3                // End of traversal?
-  |  // Copy key and value to results.
-  |.if X64
-  |  mov RBa, [BASE+8]
-  |  mov RDa, [BASE+16]
-  |  mov [BASE-8], RBa
-  |  mov [BASE], RDa
-  |.else
-  |  mov RB, [BASE+8]
-  |  mov RD, [BASE+12]
-  |  mov [BASE-8], RB
-  |  mov [BASE-4], RD
-  |  mov RB, [BASE+16]
-  |  mov RD, [BASE+20]
-  |  mov [BASE], RB
-  |  mov [BASE+4], RD
-  |.endif
-  |->fff_res2:
-  |  mov RD, 1+2
-  |  jmp ->fff_res
+  |  call extern lj_tab_next            // (GCtab *t, cTValue *key, TValue *o)
+  |  // 1=found, 0=end, -1=error returned in eax (RD).
+  |  mov BASE, RB                       // Restore BASE.
+  |  test RD, RD;  jg ->fff_res2        // Found key/value.
+  |  js ->fff_fallback_2                // Invalid key.
+  |  // End of traversal: return nil.
+  |  mov dword [BASE-4], LJ_TNIL
+  |  jmp ->fff_res1
   |2:  // Set missing 2nd arg to nil.
   |  mov dword [BASE+12], LJ_TNIL
   |  jmp <1
-  |3:  // End of traversal: return nil.
-  |  mov dword [BASE-4], LJ_TNIL
-  |  jmp ->fff_res1
   |
   |.ffunc_1 pairs
   |  mov TAB:RB, [BASE]
@@ -1775,7 +1755,9 @@ static void build_subroutines(BuildCtx *ctx)
   |  mov [BASE], RB
   |  mov [BASE+4], RD
   |.endif
-  |  jmp ->fff_res2
+  |->fff_res2:
+  |  mov RD, 1+2
+  |  jmp ->fff_res
   |2:  // Check for empty hash part first. Otherwise call C function.
   |  cmp dword TAB:RB->hmask, 0; je ->fff_res0
   |  mov FCARG1, TAB:RB
@@ -4880,7 +4862,7 @@ static void build_ins(BuildCtx *ctx, BCOp op, int defop)
     |  cmp byte CFUNC:RB->ffid, FF_next_N; jne >5
     |  branchPC RD
     |  mov dword [BASE+RA*8-8], 0       // Initialize control var.
-    |  mov dword [BASE+RA*8-4], 0xfffe7fff
+    |  mov dword [BASE+RA*8-4], LJ_KEYINDEX
     |1:
     |  ins_next
     |5:  // Despecialize bytecode if any of the checks fail.