X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=src%2Fcompiler%2Fx86-64%2Fvm.lisp;h=c946adb69a473d50424329740de9432d9e2ddba6;hb=fa464c0810199b91ffdf7f3dfab932239210a044;hp=780322020243a37cac8ea906e53264804718c3ac;hpb=86636706a92cbf7eac49c0e9a8ba9d5b49a0cd3f;p=sbcl.git

diff --git a/src/compiler/x86-64/vm.lisp b/src/compiler/x86-64/vm.lisp
index 7803220..c946adb 100644
--- a/src/compiler/x86-64/vm.lisp
+++ b/src/compiler/x86-64/vm.lisp
@@ -445,10 +445,27 @@
 
 ;;;; miscellaneous function call parameters
 
-;;; offsets of special stack frame locations
-(def!constant ocfp-save-offset 0)
-(def!constant return-pc-save-offset 1)
+;;; Offsets of special stack frame locations relative to RBP.
+;;;
+;;; Consider the standard prologue PUSH RBP; MOV RBP, RSP: the return
+;;; address is at RBP+8, the old control stack frame pointer is at
+;;; RBP, the magic 3rd slot is at RBP-8. Then come the locals from
+;;; RBP-16 on.
+(def!constant return-pc-save-offset 0)
+(def!constant ocfp-save-offset 1)
 (def!constant code-save-offset 2)
+;;; Let SP be the stack pointer before CALLing, and FP is the frame
+;;; pointer after the standard prologue. SP +
+;;; FRAME-WORD-OFFSET(SP->FP-OFFSET + I) = FP + FRAME-WORD-OFFSET(I).
+(def!constant sp->fp-offset 2)
+
+(declaim (inline frame-word-offset))
+(defun frame-word-offset (index)
+  (- (1- index)))
+
+(declaim (inline frame-byte-offset))
+(defun frame-byte-offset (index)
+  (* (frame-word-offset index) n-word-bytes))
 
 (def!constant lra-save-offset return-pc-save-offset) ; ?