From 3f9fa7e39ecb26a7fce413a9db66b5b2722cb23b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Lindqvist?= <bjourne@gmail.com>
Date: Sat, 8 Aug 2015 04:51:55 +0200
Subject: [PATCH] VM: emit_prolog/emit_epilog can be simplified because stack
 frame and safe point is always emitted together

---
 vm/quotations.cpp | 30 ++++++++++++------------------
 vm/quotations.hpp |  3 +--
 2 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/vm/quotations.cpp b/vm/quotations.cpp
index a0b79c11d6..828f384edb 100644
--- a/vm/quotations.cpp
+++ b/vm/quotations.cpp
@@ -115,19 +115,11 @@ bool quotation_jit::trivial_quotation_p(array* elements) {
 }
 
 /* Allocates memory (emit) */
-void quotation_jit::emit_prolog(bool safepoint, bool stack_frame) {
-  if (safepoint)
+void quotation_jit::emit_epilog(bool needed) {
+  if (needed) {
     emit(parent->special_objects[JIT_SAFEPOINT]);
-  if (stack_frame)
-    emit(parent->special_objects[JIT_PROLOG]);
-}
-
-/* Allocates memory (emit) */
-void quotation_jit::emit_epilog(bool safepoint, bool stack_frame) {
-  if (safepoint)
-    emit(parent->special_objects[JIT_SAFEPOINT]);
-  if (stack_frame)
     emit(parent->special_objects[JIT_EPILOG]);
+  }
 }
 
 /* Allocates memory conditionally */
@@ -147,13 +139,16 @@ void quotation_jit::emit_quotation(cell quot_) {
   }
 }
 
-/* Allocates memory (parameter(), literal(), emit_prolog, emit_with_literal)*/
+/* Allocates memory (parameter(), literal(), emit_epilog, emit_with_literal)*/
 void quotation_jit::iterate_quotation() {
   bool no_non_safepoint_words = no_non_safepoint_words_p();
 
   set_position(0);
 
-  emit_prolog(no_non_safepoint_words, no_non_safepoint_words);
+  if (no_non_safepoint_words) {
+    emit(parent->special_objects[JIT_SAFEPOINT]);
+    emit(parent->special_objects[JIT_PROLOG]);
+  }
 
   cell i;
   cell length = array_capacity(elements.untagged());
@@ -173,7 +168,7 @@ void quotation_jit::iterate_quotation() {
                                         no_non_safepoint_words);    /* stack_frame_p */
         }                                                /* Everything else */
         else if (i == length - 1) {
-          emit_epilog(no_non_safepoint_words, no_non_safepoint_words);
+          emit_epilog(no_non_safepoint_words);
           tail_call = true;
           word_jump(obj.value());
         } else
@@ -207,7 +202,7 @@ void quotation_jit::iterate_quotation() {
         /* 'if' preceded by two literal quotations (this is why if and ? are
            mutually recursive in the library, but both still work) */
         if (fast_if_p(i, length)) {
-          emit_epilog(no_non_safepoint_words, no_non_safepoint_words);
+          emit_epilog(no_non_safepoint_words);
           tail_call = true;
 
           emit_quotation(array_nth(elements.untagged(), i));
@@ -240,7 +235,7 @@ void quotation_jit::iterate_quotation() {
           /* Load the object from the datastack, then remove our stack frame. */
           emit_with_literal(parent->special_objects[PIC_LOAD],
                             tag_fixnum(-index * sizeof(cell)));
-          emit_epilog(no_non_safepoint_words, no_non_safepoint_words);
+          emit_epilog(no_non_safepoint_words);
           tail_call = true;
 
           emit_mega_cache_lookup(array_nth(elements.untagged(), i), index,
@@ -260,8 +255,7 @@ void quotation_jit::iterate_quotation() {
 
   if (!tail_call) {
     set_position(length);
-
-    emit_epilog(no_non_safepoint_words, no_non_safepoint_words);
+    emit_epilog(no_non_safepoint_words);
     emit(parent->special_objects[JIT_RETURN]);
   }
 }
diff --git a/vm/quotations.hpp b/vm/quotations.hpp
index 68a33ded02..cb61820d38 100644
--- a/vm/quotations.hpp
+++ b/vm/quotations.hpp
@@ -16,8 +16,7 @@ struct quotation_jit : public jit {
   bool primitive_call_p(cell i, cell length);
   bool trivial_quotation_p(array* elements);
   void emit_quotation(cell quot);
-  void emit_prolog(bool safepoint, bool stack_frame);
-  void emit_epilog(bool safepoint, bool stack_frame);
+  void emit_epilog(bool needed);
   bool fast_if_p(cell i, cell length);
   bool fast_dip_p(cell i, cell length);
   bool fast_2dip_p(cell i, cell length);