From e0dc2367255f96d7622211e90d0617986e339630 Mon Sep 17 00:00:00 2001
From: Joe Groff <arcata@gmail.com>
Date: Sat, 12 Nov 2011 12:57:24 -0800
Subject: [PATCH] cpu.*.bootstrap: clear faulting flag directly No reason to go
 through a safepoint in unwind-native-frames really.

---
 basis/compiler/constants/constants.factor |  1 +
 basis/cpu/x86/32/bootstrap.factor         | 10 +++++-----
 basis/cpu/x86/64/bootstrap.factor         | 11 +++++------
 basis/vm/vm.factor                        |  1 +
 vm/errors.cpp                             |  5 ++---
 vm/vm.hpp                                 |  4 +++-
 6 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/basis/compiler/constants/constants.factor b/basis/compiler/constants/constants.factor
index 85aa5c4439..7951c1ef0b 100644
--- a/basis/compiler/constants/constants.factor
+++ b/basis/compiler/constants/constants.factor
@@ -30,6 +30,7 @@ CONSTANT: deck-bits 18
 : vm-context-offset ( -- n ) 0 bootstrap-cells ; inline
 : vm-spare-context-offset ( -- n ) 1 bootstrap-cells ; inline
 : vm-signal-handler-addr-offset ( -- n ) 8 bootstrap-cells ; inline
+: vm-fault-flag-offset ( -- n ) 9 bootstrap-cells ; inline
 : context-callstack-top-offset ( -- n ) 0 bootstrap-cells ; inline
 : context-callstack-bottom-offset ( -- n ) 1 bootstrap-cells ; inline
 : context-datastack-offset ( -- n ) 2 bootstrap-cells ; inline
diff --git a/basis/cpu/x86/32/bootstrap.factor b/basis/cpu/x86/32/bootstrap.factor
index c234d03a44..23b05548b0 100755
--- a/basis/cpu/x86/32/bootstrap.factor
+++ b/basis/cpu/x86/32/bootstrap.factor
@@ -140,16 +140,14 @@ IN: bootstrap.x86
 [ jit-jump-quot ]
 \ (call) define-combinator-primitive
 
-: (jit-safepoint) ( -- )
-    0 EAX MOVABS rc-absolute rel-safepoint ;
 [
     ! Load ds and rs registers
     jit-load-vm
     jit-load-context
     jit-restore-context
 
-    ! Safepoint to clear the faulting flag in the VM
-     (jit-safepoint)
+    ! clear the fault flag
+    vm-reg vm-fault-flag-offset [+] 0 MOV
 
     ! Windows-specific setup
     ctx-reg jit-update-seh
@@ -400,7 +398,9 @@ IN: bootstrap.x86
     EAX EDX [] MOV
     jit-jump-quot ;
 
-[ (jit-safepoint) ] \ jit-safepoint jit-define
+[
+    0 EAX MOVABS rc-absolute rel-safepoint
+] \ jit-safepoint jit-define
 
 [
     jit-start-context-and-delete
diff --git a/basis/cpu/x86/64/bootstrap.factor b/basis/cpu/x86/64/bootstrap.factor
index 77e76db9b7..e299dbf348 100755
--- a/basis/cpu/x86/64/bootstrap.factor
+++ b/basis/cpu/x86/64/bootstrap.factor
@@ -122,9 +122,6 @@ IN: bootstrap.x86
 [ jit-jump-quot ]
 \ (call) define-combinator-primitive
 
-: (jit-safepoint)
-    0 [RIP+] EAX MOV rc-relative rel-safepoint ;
-
 [
     ! Unwind stack frames
     RSP arg2 MOV
@@ -137,8 +134,8 @@ IN: bootstrap.x86
     jit-load-context
     jit-restore-context
 
-    ! Safepoint to clear the faulting flag in the VM
-    (jit-safepoint)
+    ! Clear the fault flag
+    vm-reg vm-fault-flag-offset [+] 0 MOV
 
     ! Call quotation
     jit-jump-quot
@@ -342,7 +339,9 @@ IN: bootstrap.x86
     jit-push-param
     jit-jump-quot ;
 
-[ (jit-safepoint) ] \ jit-safepoint jit-define
+[
+    0 [RIP+] EAX MOV rc-relative rel-safepoint
+] \ jit-safepoint jit-define
 
 [
     jit-start-context-and-delete
diff --git a/basis/vm/vm.factor b/basis/vm/vm.factor
index 46bf2954dd..3f18699c4d 100644
--- a/basis/vm/vm.factor
+++ b/basis/vm/vm.factor
@@ -31,6 +31,7 @@ STRUCT: vm
 { cards-offset cell }
 { decks-offset cell }
 { signal-handler-addr cell }
+{ faulting? cell }
 { special-objects cell[special-object-count] } ;
 
 : vm-field-offset ( field -- offset ) vm offset-of ; inline
diff --git a/vm/errors.cpp b/vm/errors.cpp
index 14a8700dcf..b775eec015 100755
--- a/vm/errors.cpp
+++ b/vm/errors.cpp
@@ -73,9 +73,8 @@ void factor_vm::general_error(vm_error_type error, cell arg1, cell arg2)
 
 		ctx->push(error_object);
 
-		/* Guard the safepoint, which will clear faulting_p if unwind-native-frames
-		succeeds */
-		code->guard_safepoint();
+		/* The unwind-native-frames subprimitive will clear faulting_p
+		if it was successfully reached. */
 		unwind_native_frames(special_objects[ERROR_HANDLER_QUOT],
 			ctx->callstack_top);
 	}
diff --git a/vm/vm.hpp b/vm/vm.hpp
index 5cd8b1f05c..cfe77bd7fd 100755
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -28,6 +28,9 @@ struct factor_vm
 	/* cdecl signal handler address, used by signal handler subprimitives */
 	cell signal_handler_addr;
 
+	/* are we handling a memory error? used to detect double faults */
+	cell faulting_p;
+
 	/* Various special objects, accessed by special-object and
 	set-special-object primitives */
 	cell special_objects[special_object_count];
@@ -142,7 +145,6 @@ struct factor_vm
 	segment *signal_callstack_seg;
 
 	/* Are we already handling a fault? Used to catch double memory faults */
-	bool faulting_p;
 	static bool fatal_erroring_p;
 
 	/* Safepoint state */