Merge Label and NearLabel

src/ia32/assembler-ia32.cc

Index: src/ia32/assembler-ia32.cc
diff --git a/src/ia32/assembler-ia32.cc b/src/ia32/assembler-ia32.cc
index 043eb2ef7ad8a8bebba9667ca23cfe6adce3d550..06f150bc21e8a305f3d2b846396cfc1198f48dbc 100644
--- a/src/ia32/assembler-ia32.cc
+++ b/src/ia32/assembler-ia32.cc
@@ -1525,6 +1525,21 @@ void Assembler::bind_to(Label* L, int pos) {
     }
     disp.next(L);
   }
+  while (L->is_near_linked()) {
+    int fixup_pos = L->near_link_pos();
+    int offset_to_next =
+        static_cast<int>(*reinterpret_cast<int8_t*>(addr_at(fixup_pos)));
+    ASSERT(offset_to_next <= 0);
+    // Relative address, relative to point after address.
+    int disp = pos - fixup_pos - sizeof(int8_t);
+    ASSERT(0 <= disp && disp <= 127);
+    set_byte_at(fixup_pos, disp);
+    if (offset_to_next < 0) {
+      L->link_to(fixup_pos + offset_to_next, Label::kNear);
+    } else {
+      L->UnuseNear();
+    }
+  }
   L->bind_to(pos);
 }
 
@@ -1613,7 +1628,7 @@ void Assembler::call(Handle<Code> code,
 }
 
 
-void Assembler::jmp(Label* L) {
+void Assembler::jmp(Label* L, bool near) {
   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
   if (L->is_bound()) {
@@ -1630,6 +1645,9 @@ void Assembler::jmp(Label* L) {
       EMIT(0xE9);
       emit(offs - long_size);
     }
+  } else if (near == Label::kNear) {
+    EMIT(0xEB);
+    emit_near_disp(L);
   } else {
     // 1110 1001 #32-bit disp.
     EMIT(0xE9);
@@ -1683,7 +1701,7 @@ void Assembler::jmp(NearLabel* L) {
 }
 
 
-void Assembler::j(Condition cc, Label* L, Hint hint) {
+void Assembler::j(Condition cc, Label* L, bool near, Hint hint) {

[danno, 2011/05/09 14:59:56]

Can you please make this the last optional parameter? Now that you've found and
replaced all of them, that shouldn't be so hard. Makes the far (default) case
compacter.

[fschneider, 2011/05/09 15:37:36]

I think we could even get rid of the Hint parameter. No modern Intel
architecture actually benefits from these anyway. I'm not sure if we emit them
at all in the generated code.

[Jakob Kummerow, 2011/05/09 16:25:24]

Done.

[Jakob Kummerow, 2011/05/09 16:25:24]

shell --help says:
  --emit_branch_hints (emit branch hints)
        type: bool  default: false
So yeah, I guess we can get rid of them. But I would propose to do that in
another CL, since it's not directly related to the NearLabel refactoring.

   EnsureSpace ensure_space(this);
   last_pc_ = pc_;
   ASSERT(0 <= cc && cc < 16);
@@ -1703,6 +1721,9 @@ void Assembler::j(Condition cc, Label* L, Hint hint) {
       EMIT(0x80 | cc);
       emit(offs - long_size);
     }
+  } else if (near == Label::kNear) {
+    EMIT(0x70 | cc);
+    emit_near_disp(L);
   } else {
     // 0000 1111 1000 tttn #32-bit disp
     // Note: could eliminate cond. jumps to this jump if condition