From 07aee7525f51d0ddc5aa90574293f2cad8a7db67 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Lindqvist?= <bjourne@gmail.com>
Date: Sun, 27 Mar 2016 19:14:29 +0200
Subject: [PATCH] compiler.cfg.save-contexts: ##save-context isn't need in
 front of ##call-gc

The reason is because the minor-gc primitive itself saves the
context. Not inlining context saves, saves 20 bytes/call site.
---
 .../compiler/cfg/save-contexts/save-contexts-docs.factor  | 7 ++++---
 .../compiler/cfg/save-contexts/save-contexts-tests.factor | 3 ++-
 basis/compiler/cfg/save-contexts/save-contexts.factor     | 8 +++++++-
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/basis/compiler/cfg/save-contexts/save-contexts-docs.factor b/basis/compiler/cfg/save-contexts/save-contexts-docs.factor
index c2ccd26ec5..20c8001163 100644
--- a/basis/compiler/cfg/save-contexts/save-contexts-docs.factor
+++ b/basis/compiler/cfg/save-contexts/save-contexts-docs.factor
@@ -1,5 +1,5 @@
 USING: compiler.cfg compiler.cfg.instructions help.markup help.syntax
-math sequences kernel ;
+kernel math memory sequences ;
 IN: compiler.cfg.save-contexts
 
 HELP: insert-save-contexts
@@ -17,9 +17,10 @@ HELP: save-context-offset
 { $description { $link ##save-context } " must be placed after instructions that modify the context, or instructions that read parameter registers." } ;
 
 ARTICLE: "compiler.cfg.save-contexts" "Insert context saves"
-"Inserts " { $link ##save-context } " in blocks that need them."
+"Inserts " { $link ##save-context } " in blocks that need them. If an instruction does something that might trigger a GC sweep, such as calling a C function, then the context must be saved before."
 $nl
 "Main word:"
-{ $subsections insert-save-contexts } ;
+{ $subsections insert-save-contexts }
+{ $notes "The " { ##call-gc } " instruction does not need a context save because the primitive implementing the instruction (" { $link minor-gc } ") already saves the context for us." } ;
 
 ABOUT: "compiler.cfg.save-contexts"
diff --git a/basis/compiler/cfg/save-contexts/save-contexts-tests.factor b/basis/compiler/cfg/save-contexts/save-contexts-tests.factor
index b42bd3f5d3..b54bda7334 100644
--- a/basis/compiler/cfg/save-contexts/save-contexts-tests.factor
+++ b/basis/compiler/cfg/save-contexts/save-contexts-tests.factor
@@ -5,7 +5,7 @@ cpu.x86.assembler.operands cpu.architecture ;
 IN: compiler.cfg.save-contexts.tests
 
 ! insns-needs-save-context?
-{ t f } [
+{ f f t } [
     {
         T{ ##call-gc }
     } insns-needs-save-context?
@@ -13,6 +13,7 @@ IN: compiler.cfg.save-contexts.tests
         T{ ##add f 1 2 3 }
         T{ ##branch }
     } insns-needs-save-context?
+    { T{ ##alien-invoke } } insns-needs-save-context?
 ] unit-test
 
 H{ } clone representations set
diff --git a/basis/compiler/cfg/save-contexts/save-contexts.factor b/basis/compiler/cfg/save-contexts/save-contexts.factor
index ef7474395f..19f43bfc11 100644
--- a/basis/compiler/cfg/save-contexts/save-contexts.factor
+++ b/basis/compiler/cfg/save-contexts/save-contexts.factor
@@ -9,8 +9,14 @@ UNION: context-modifier ##phi ##inc ##callback-inputs ;
 : save-context-offset ( insns -- n )
     [ context-modifier? not ] find drop ;
 
+UNION: needs-save-context-insn
+    ##alien-invoke
+    ##alien-indirect
+    ##box-long-long
+    ##box ;
+
 : insns-needs-save-context? ( insns -- ? )
-    [ gc-map-insn? ] any? ;
+    [ needs-save-context-insn? ] any? ;
 
 : insert-save-context ( insns -- insns' )
     dup insns-needs-save-context? [