(defun my-make-wired-tn (prim-type-name sc-name offset)
(make-wired-tn (primitive-type-or-lose prim-type-name)
- (sc-number-or-lose sc-name)
- offset))
+ (sc-number-or-lose sc-name)
+ offset))
(defstruct (arg-state (:copier nil))
(register-args 0)
(xmm-args 0)
(stack-frame-size 0))
+(defconstant max-int-args #.(length *c-call-register-arg-offsets*))
+(defconstant max-xmm-args #!+win32 4 #!-win32 8)
+
(defun int-arg (state prim-type reg-sc stack-sc)
- (let ((reg-args (arg-state-register-args state)))
- (cond ((< reg-args 6)
- (setf (arg-state-register-args state) (1+ reg-args))
- (my-make-wired-tn prim-type reg-sc
- (nth reg-args *c-call-register-arg-offsets*)))
- (t
- (let ((frame-size (arg-state-stack-frame-size state)))
- (setf (arg-state-stack-frame-size state) (1+ frame-size))
- (my-make-wired-tn prim-type stack-sc frame-size))))))
+ (let ((reg-args (max (arg-state-register-args state)
+ #!+win32 (arg-state-xmm-args state))))
+ (cond ((< reg-args max-int-args)
+ (setf (arg-state-register-args state) (1+ reg-args))
+ (my-make-wired-tn prim-type reg-sc
+ (nth reg-args *c-call-register-arg-offsets*)))
+ (t
+ (let ((frame-size (arg-state-stack-frame-size state)))
+ (setf (arg-state-stack-frame-size state) (1+ frame-size))
+ (my-make-wired-tn prim-type stack-sc frame-size))))))
(define-alien-type-method (integer :arg-tn) (type state)
(if (alien-integer-type-signed type)
(int-arg state 'system-area-pointer 'sap-reg 'sap-stack))
(defun float-arg (state prim-type reg-sc stack-sc)
- (let ((xmm-args (arg-state-xmm-args state)))
- (cond ((< xmm-args 8)
- (setf (arg-state-xmm-args state) (1+ xmm-args))
- (my-make-wired-tn prim-type reg-sc
- (nth xmm-args *float-regs*)))
- (t
- (let ((frame-size (arg-state-stack-frame-size state)))
- (setf (arg-state-stack-frame-size state) (1+ frame-size))
- (my-make-wired-tn prim-type stack-sc frame-size))))))
+ (let ((xmm-args (max (arg-state-xmm-args state)
+ #!+win32 (arg-state-register-args state))))
+ (cond ((< xmm-args max-xmm-args)
+ (setf (arg-state-xmm-args state) (1+ xmm-args))
+ (my-make-wired-tn prim-type reg-sc
+ (nth xmm-args *float-regs*)))
+ (t
+ (let ((frame-size (arg-state-stack-frame-size state)))
+ (setf (arg-state-stack-frame-size state) (1+ frame-size))
+ (my-make-wired-tn prim-type stack-sc frame-size))))))
(define-alien-type-method (double-float :arg-tn) (type state)
(declare (ignore type))
(0 eax-offset)
(1 edx-offset)))
-;; XXX The return handling probably doesn't conform to the ABI
-
(define-alien-type-method (integer :result-tn) (type state)
(let ((num-results (result-state-num-results state)))
(setf (result-state-num-results state) (1+ num-results))
(multiple-value-bind (ptype reg-sc)
- (if (alien-integer-type-signed type)
- (values 'signed-byte-64 'signed-reg)
- (values 'unsigned-byte-64 'unsigned-reg))
+ (if (alien-integer-type-signed type)
+ (values 'signed-byte-64 'signed-reg)
+ (values 'unsigned-byte-64 'unsigned-reg))
(my-make-wired-tn ptype reg-sc (result-reg-offset num-results)))))
(define-alien-type-method (integer :naturalize-gen) (type alien)
- (if (and (alien-integer-type-signed type)
- (<= (alien-type-bits type) 32))
- `(sign-extend ,alien)
+ (if (<= (alien-type-bits type) 32)
+ (if (alien-integer-type-signed type)
+ `(sign-extend ,alien ,(alien-type-bits type))
+ `(logand ,alien ,(1- (ash 1 (alien-type-bits type)))))
alien))
(define-alien-type-method (system-area-pointer :result-tn) (type state)
(let ((num-results (result-state-num-results state)))
(setf (result-state-num-results state) (1+ num-results))
(my-make-wired-tn 'system-area-pointer 'sap-reg
- (result-reg-offset num-results))))
+ (result-reg-offset num-results))))
(define-alien-type-method (double-float :result-tn) (type state)
(declare (ignore type))
(when (> (length values) 2)
(error "Too many result values from c-call."))
(mapcar (lambda (type)
- (invoke-alien-type-method :result-tn type state))
- values)))
+ (invoke-alien-type-method :result-tn type state))
+ values)))
-(!def-vm-support-routine make-call-out-tns (type)
+(defun make-call-out-tns (type)
(let ((arg-state (make-arg-state)))
(collect ((arg-tns))
(dolist (arg-type (alien-fun-type-arg-types type))
- (arg-tns (invoke-alien-type-method :arg-tn arg-type arg-state)))
+ (arg-tns (invoke-alien-type-method :arg-tn arg-type arg-state)))
(values (my-make-wired-tn 'positive-fixnum 'any-reg esp-offset)
- (* (arg-state-stack-frame-size arg-state) n-word-bytes)
- (arg-tns)
- (invoke-alien-type-method :result-tn
- (alien-fun-type-result-type type)
- (make-result-state))))))
+ (* (arg-state-stack-frame-size arg-state) n-word-bytes)
+ (arg-tns)
+ (invoke-alien-type-method :result-tn
+ (alien-fun-type-result-type type)
+ (make-result-state))))))
(deftransform %alien-funcall ((function type &rest args) * * :node node)
(aver (sb!c::constant-lvar-p type))
(let* ((type (sb!c::lvar-value type))
- (env (sb!c::node-lexenv node))
+ (env (sb!c::node-lexenv node))
(arg-types (alien-fun-type-arg-types type))
(result-type (alien-fun-type-result-type type)))
(aver (= (length arg-types) (length args)))
(lambda-vars arg)
(cond ((and (alien-integer-type-p type)
(> (sb!alien::alien-integer-type-bits type) 64))
+ ;; CLH: FIXME! This should really be
+ ;; #xffffffffffffffff. nyef says: "Passing
+ ;; 128-bit integers to ALIEN functions on x86-64
+ ;; believed to be broken."
(new-args `(logand ,arg #xffffffff))
(new-args `(ash ,arg -64))
(new-arg-types (parse-alien-type '(unsigned 64) env))
(if (alien-integer-type-signed result-type)
'(values (unsigned 64) (signed 64))
'(values (unsigned 64) (unsigned 64)))
- env))))
+ env))))
`(lambda (function type ,@(lambda-vars))
(declare (ignore type))
(multiple-value-bind (low high)
,@(new-args))))))
(sb!c::give-up-ir1-transform))))
-;;; The ABI specifies that signed short/int's are returned as 32-bit
-;;; values. Negative values need to be sign-extended to 64-bits (done
-;;; in a :NATURALIZE-GEN alien-type-method).
-(defknown sign-extend (fixnum) fixnum (foldable flushable movable))
+;;; The ABI is vague about how signed sub-word integer return values
+;;; are handled, but since gcc versions >=4.3 no longer do sign
+;;; extension in the callee, we need to do it in the caller. FIXME:
+;;; If the value to be extended is known to already be of the target
+;;; type at compile time, we can (and should) elide the extension.
+(defknown sign-extend ((signed-byte 64) t) fixnum
+ (foldable flushable movable))
(define-vop (sign-extend)
(:translate sign-extend)
(:policy :fast-safe)
- (:args (val :scs (any-reg)))
- (:arg-types fixnum)
- (:results (res :scs (any-reg)))
+ (:args (val :scs (signed-reg)))
+ (:arg-types signed-num (:constant fixnum))
+ (:info size)
+ (:results (res :scs (signed-reg)))
(:result-types fixnum)
(:generator 1
(inst movsxd res
- (make-random-tn :kind :normal
- :sc (sc-or-lose 'dword-reg)
- :offset (tn-offset val)))))
-
-(defun sign-extend (x)
- (if (logbitp 31 x)
- (dpb x (byte 32 0) -1)
- (ldb (byte 32 0) x)))
-
-(define-vop (foreign-symbol-address)
- (:translate foreign-symbol-address)
+ (make-random-tn :kind :normal
+ :sc (sc-or-lose (ecase size
+ (8 'byte-reg)
+ (16 'word-reg)
+ (32 'dword-reg)))
+ :offset (tn-offset val)))))
+
+#-sb-xc-host
+(defun sign-extend (x size)
+ (declare (type (signed-byte 64) x))
+ (ecase size
+ (8 (sign-extend x size))
+ (16 (sign-extend x size))
+ (32 (sign-extend x size))))
+
+#+sb-xc-host
+(defun sign-extend (x size)
+ (if (logbitp (1- size) x)
+ (dpb x (byte size 0) -1)
+ x))
+
+(define-vop (foreign-symbol-sap)
+ (:translate foreign-symbol-sap)
(:policy :fast-safe)
(:args)
(:arg-types (:constant simple-string))
(:results (res :scs (sap-reg)))
(:result-types system-area-pointer)
(:generator 2
- (inst lea res (make-fixup (extern-alien-name foreign-symbol) :foreign))))
+ (inst mov res (make-fixup foreign-symbol :foreign))))
#!+linkage-table
-(define-vop (foreign-symbol-dataref-address)
- (:translate foreign-symbol-dataref-address)
+(define-vop (foreign-symbol-dataref-sap)
+ (:translate foreign-symbol-dataref-sap)
(:policy :fast-safe)
(:args)
(:arg-types (:constant simple-string))
(:results (res :scs (sap-reg)))
(:result-types system-area-pointer)
(:generator 2
- (inst mov res (make-fixup (extern-alien-name foreign-symbol) :foreign-dataref))))
+ (inst mov res (make-fixup foreign-symbol :foreign-dataref))))
(define-vop (call-out)
- (:args (function :scs (sap-reg))
- (args :more t))
+ (:args (function :scs (sap-reg)
+ :target rbx)
+ (args :more t))
(:results (results :more t))
+ ;; RBX is used to first load the address, allowing the debugger to
+ ;; determine which alien was accessed in case it's undefined.
+ (:temporary (:sc sap-reg :offset rbx-offset) rbx)
(:temporary (:sc unsigned-reg :offset rax-offset :to :result) rax)
- (:ignore results)
+ ;; For safepoint builds: Force values of non-volatiles to the stack.
+ ;; These are the callee-saved registers in the native ABI, but
+ ;; safepoint-based GC needs to see all Lisp values on the stack. Note
+ ;; that R12-R15 are non-volatile registers, but there is no need to
+ ;; spill R12 because it is our thread-base-tn. RDI and RSI are
+ ;; non-volatile on Windows, but argument passing registers on other
+ ;; platforms.
+ #!+sb-safepoint (:temporary (:sc unsigned-reg :offset r13-offset) r13)
+ #!+sb-safepoint (:temporary (:sc unsigned-reg :offset r14-offset) r14)
+ #!+sb-safepoint (:temporary (:sc unsigned-reg :offset r15-offset) r15)
+ #!+(and sb-safepoint win32) (:temporary
+ (:sc unsigned-reg :offset rdi-offset) rdi)
+ #!+(and sb-safepoint win32) (:temporary
+ (:sc unsigned-reg :offset rsi-offset) rsi)
+ (:ignore results
+ #!+(and sb-safepoint win32) rdi
+ #!+(and sb-safepoint win32) rsi
+ #!+win32 args
+ #!+win32 rax
+ #!+sb-safepoint r15
+ #!+sb-safepoint r13)
(:vop-var vop)
(:save-p t)
(:generator 0
+ ;; ABI: Direction flag must be clear on function entry. -- JES, 2006-01-20
+ (inst cld)
+ #!+sb-safepoint
+ (progn
+ ;; Current PC - don't rely on function to keep it in a form that
+ ;; GC understands
+ (let ((label (gen-label)))
+ (inst lea r14 (make-fixup nil :code-object label))
+ (emit-label label)))
+ #!-win32
;; ABI: AL contains amount of arguments passed in XMM registers
;; for vararg calls.
(move-immediate rax
- (loop for tn-ref = args then (tn-ref-across tn-ref)
- while tn-ref
- count (eq (sb-name (sc-sb (tn-sc (tn-ref-tn tn-ref))))
- 'float-registers)))
- (inst call function)
+ (loop for tn-ref = args then (tn-ref-across tn-ref)
+ while tn-ref
+ count (eq (sb-name (sc-sb (tn-sc (tn-ref-tn tn-ref))))
+ 'float-registers)))
+ #!+win32 (inst sub rsp-tn #x20) ;MS_ABI: shadow zone
+ #!+sb-safepoint
+ (progn ;Store SP and PC in thread struct
+ (storew rsp-tn thread-base-tn thread-saved-csp-offset)
+ (storew r14 thread-base-tn thread-pc-around-foreign-call-slot))
+ (move rbx function)
+ (inst call rbx)
+ #!+win32 (inst add rsp-tn #x20) ;MS_ABI: remove shadow space
+ #!+sb-safepoint
+ (progn
+ ;; Zeroing out
+ (inst xor r14 r14)
+ ;; Zero PC storage place. NB. CSP-then-PC: same sequence on
+ ;; entry/exit, is actually corrent.
+ (storew r14 thread-base-tn thread-saved-csp-offset)
+ (storew r14 thread-base-tn thread-pc-around-foreign-call-slot))
;; To give the debugger a clue. XX not really internal-error?
- (note-this-location vop :internal-error)
- ;; FLOAT15 needs to contain FP zero in Lispland
- (let ((float15 (make-random-tn :kind :normal
- :sc (sc-or-lose 'double-reg)
- :offset float15-offset)))
- (inst xorpd float15 float15))))
+ (note-this-location vop :internal-error)))
(define-vop (alloc-number-stack-space)
(:info amount)
(:results (result :scs (sap-reg any-reg)))
+ (:result-types system-area-pointer)
(:generator 0
(aver (location= result rsp-tn))
(unless (zerop amount)
(let ((delta (logandc2 (+ amount 7) 7)))
- (inst sub rsp-tn delta)))
+ (inst sub rsp-tn delta)))
;; C stack must be 16 byte aligned
- (inst and rsp-tn #xfffffff0)
+ (inst and rsp-tn -16)
(move result rsp-tn)))
(define-vop (dealloc-number-stack-space)
(:generator 0
(unless (zerop amount)
(let ((delta (logandc2 (+ amount 7) 7)))
- (inst add rsp-tn delta)))))
+ (inst add rsp-tn delta)))))
(define-vop (alloc-alien-stack-space)
(:info amount)
#!+sb-thread (:temporary (:sc unsigned-reg) temp)
(:results (result :scs (sap-reg any-reg)))
+ (:result-types system-area-pointer)
#!+sb-thread
(:generator 0
(aver (not (location= result rsp-tn)))
(unless (zerop amount)
(let ((delta (logandc2 (+ amount 7) 7)))
- (inst mov temp
- (make-ea :dword
- :disp (+ nil-value
- (static-symbol-offset '*alien-stack*)
- (ash symbol-tls-index-slot word-shift)
- (- other-pointer-lowtag))))
- (inst fs-segment-prefix)
- (inst sub (make-ea :dword :scale 1 :index temp) delta)))
+ (inst mov temp
+ (make-ea :qword
+ :disp (+ nil-value
+ (static-symbol-offset '*alien-stack*)
+ (ash symbol-tls-index-slot word-shift)
+ (- other-pointer-lowtag))))
+ (inst sub (make-ea :qword :base thread-base-tn
+ :scale 1 :index temp) delta)))
(load-tl-symbol-value result *alien-stack*))
#!-sb-thread
(:generator 0
(:generator 0
(unless (zerop amount)
(let ((delta (logandc2 (+ amount 7) 7)))
- (inst mov temp
- (make-ea :dword
- :disp (+ nil-value
- (static-symbol-offset '*alien-stack*)
- (ash symbol-tls-index-slot word-shift)
- (- other-pointer-lowtag))))
- (inst fs-segment-prefix)
- (inst add (make-ea :dword :scale 1 :index temp) delta))))
+ (inst mov temp
+ (make-ea :qword
+ :disp (+ nil-value
+ (static-symbol-offset '*alien-stack*)
+ (ash symbol-tls-index-slot word-shift)
+ (- other-pointer-lowtag))))
+ (inst add (make-ea :qword :base thread-base-tn :scale 1 :index temp)
+ delta))))
#!-sb-thread
(:generator 0
(unless (zerop amount)
(- other-pointer-lowtag)))
delta)))))
-;;; these are not strictly part of the c-call convention, but are
-;;; needed for the WITH-PRESERVED-POINTERS macro used for "locking
-;;; down" lisp objects so that GC won't move them while foreign
-;;; functions go to work.
-
-(define-vop (push-word-on-c-stack)
- (:translate push-word-on-c-stack)
- (:args (val :scs (sap-reg)))
+;;; not strictly part of the c-call convention, but needed for the
+;;; WITH-PINNED-OBJECTS macro used for "locking down" lisp objects so
+;;; that GC won't move them while foreign functions go to work.
+(define-vop (touch-object)
+ (:translate touch-object)
+ (:args (object))
+ (:ignore object)
(:policy :fast-safe)
- (:arg-types system-area-pointer)
- (:generator 2
- (inst push val)))
-
-(define-vop (pop-words-from-c-stack)
- (:translate pop-words-from-c-stack)
- (:args)
- (:arg-types (:constant (unsigned-byte 60)))
- (:info number)
- (:policy :fast-safe)
- (:generator 2
- (inst add rsp-tn (fixnumize number))))
-
+ (:arg-types t)
+ (:generator 0))
+
+;;; Callbacks
+
+#-sb-xc-host
+(defun alien-callback-accessor-form (type sp offset)
+ `(deref (sap-alien (sap+ ,sp ,offset) (* ,type))))
+
+#-sb-xc-host
+(defun alien-callback-assembler-wrapper (index result-type argument-types)
+ (labels ((make-tn-maker (sc-name)
+ (lambda (offset)
+ (make-random-tn :kind :normal
+ :sc (sc-or-lose sc-name)
+ :offset offset)))
+ (out-of-registers-error ()
+ (error "Too many arguments in callback")))
+ (let* ((segment (make-segment))
+ (rax rax-tn)
+ #!+(or win32 (not sb-safepoint)) (rcx rcx-tn)
+ #!-win32 (rdi rdi-tn)
+ #!-win32 (rsi rsi-tn)
+ (rdx rdx-tn)
+ (rbp rbp-tn)
+ (rsp rsp-tn)
+ #!+win32 (r8 r8-tn)
+ (xmm0 float0-tn)
+ ([rsp] (make-ea :qword :base rsp :disp 0))
+ ;; How many arguments have been copied
+ (arg-count 0)
+ ;; How many arguments have been copied from the stack
+ (stack-argument-count #!-win32 0 #!+win32 4)
+ (gprs (mapcar (make-tn-maker 'any-reg) *c-call-register-arg-offsets*))
+ (fprs (mapcar (make-tn-maker 'double-reg)
+ ;; Only 8 first XMM registers are used for
+ ;; passing arguments
+ (subseq *float-regs* 0 #!-win32 8 #!+win32 4))))
+ (assemble (segment)
+ ;; Make room on the stack for arguments.
+ (inst sub rsp (* n-word-bytes (length argument-types)))
+ ;; Copy arguments from registers to stack
+ (dolist (type argument-types)
+ (let ((integerp (not (alien-float-type-p type)))
+ ;; A TN pointing to the stack location where the
+ ;; current argument should be stored for the purposes
+ ;; of ENTER-ALIEN-CALLBACK.
+ (target-tn (make-ea :qword :base rsp
+ :disp (* arg-count
+ n-word-bytes)))
+ ;; A TN pointing to the stack location that contains
+ ;; the next argument passed on the stack.
+ (stack-arg-tn (make-ea :qword :base rsp
+ :disp (* (+ 1
+ (length argument-types)
+ stack-argument-count)
+ n-word-bytes))))
+ (incf arg-count)
+ (cond (integerp
+ (let ((gpr (pop gprs)))
+ #!+win32 (pop fprs)
+ ;; Argument not in register, copy it from the old
+ ;; stack location to a temporary register.
+ (unless gpr
+ (incf stack-argument-count)
+ (setf gpr temp-reg-tn)
+ (inst mov gpr stack-arg-tn))
+ ;; Copy from either argument register or temporary
+ ;; register to target.
+ (inst mov target-tn gpr)))
+ ((or (alien-single-float-type-p type)
+ (alien-double-float-type-p type))
+ (let ((fpr (pop fprs)))
+ #!+win32 (pop gprs)
+ (cond (fpr
+ ;; Copy from float register to target location.
+ (inst movq target-tn fpr))
+ (t
+ ;; Not in float register. Copy from stack to
+ ;; temporary (general purpose) register, and
+ ;; from there to the target location.
+ (incf stack-argument-count)
+ (inst mov temp-reg-tn stack-arg-tn)
+ (inst mov target-tn temp-reg-tn)))))
+ (t
+ (bug "Unknown alien floating point type: ~S" type)))))
+
+ #!-sb-safepoint
+ (progn
+ ;; arg0 to FUNCALL3 (function)
+ ;;
+ ;; Indirect the access to ENTER-ALIEN-CALLBACK through
+ ;; the symbol-value slot of SB-ALIEN::*ENTER-ALIEN-CALLBACK*
+ ;; to ensure it'll work even if the GC moves ENTER-ALIEN-CALLBACK.
+ ;; Skip any SB-THREAD TLS magic, since we don't expect anyone
+ ;; to rebind the variable. -- JES, 2006-01-01
+ (inst mov rdi (+ nil-value (static-symbol-offset
+ 'sb!alien::*enter-alien-callback*)))
+ (loadw rdi rdi symbol-value-slot other-pointer-lowtag)
+ ;; arg0 to ENTER-ALIEN-CALLBACK (trampoline index)
+ (inst mov rsi (fixnumize index))
+ ;; arg1 to ENTER-ALIEN-CALLBACK (pointer to argument vector)
+ (inst mov rdx rsp)
+ ;; add room on stack for return value
+ (inst sub rsp 8)
+ ;; arg2 to ENTER-ALIEN-CALLBACK (pointer to return value)
+ (inst mov rcx rsp)
+
+ ;; Make new frame
+ (inst push rbp)
+ (inst mov rbp rsp)
+
+ ;; Call
+ (inst mov rax (foreign-symbol-address "funcall3"))
+ (inst call rax)
+
+ ;; Back! Restore frame
+ (inst mov rsp rbp)
+ (inst pop rbp))
+
+ #!+sb-safepoint
+ (progn
+ ;; arg0 to ENTER-ALIEN-CALLBACK (trampoline index)
+ (inst mov #!-win32 rdi #!+win32 rcx (fixnumize index))
+ ;; arg1 to ENTER-ALIEN-CALLBACK (pointer to argument vector)
+ (inst mov #!-win32 rsi #!+win32 rdx rsp)
+ ;; add room on stack for return value
+ (inst sub rsp 8)
+ ;; arg2 to ENTER-ALIEN-CALLBACK (pointer to return value)
+ (inst mov #!-win32 rdx #!+win32 r8 rsp)
+ ;; Make new frame
+ (inst push rbp)
+ (inst mov rbp rsp)
+ #!+win32 (inst sub rsp #x20)
+ #!+win32 (inst and rsp #x-20)
+ ;; Call
+ (inst mov rax (foreign-symbol-address "callback_wrapper_trampoline"))
+ (inst call rax)
+ ;; Back! Restore frame
+ (inst mov rsp rbp)
+ (inst pop rbp))
+
+ ;; Result now on top of stack, put it in the right register
+ (cond
+ ((or (alien-integer-type-p result-type)
+ (alien-pointer-type-p result-type)
+ (alien-type-= #.(parse-alien-type 'system-area-pointer nil)
+ result-type))
+ (inst mov rax [rsp]))
+ ((or (alien-single-float-type-p result-type)
+ (alien-double-float-type-p result-type))
+ (inst movq xmm0 [rsp]))
+ ((alien-void-type-p result-type))
+ (t
+ (error "unrecognized alien type: ~A" result-type)))
+
+ ;; Pop the arguments and the return value from the stack to get
+ ;; the return address at top of stack.
+ (inst add rsp (* (1+ (length argument-types)) n-word-bytes))
+ ;; Return
+ (inst ret))
+ (finalize-segment segment)
+ ;; Now that the segment is done, convert it to a static
+ ;; vector we can point foreign code to.
+ (let ((buffer (sb!assem::segment-buffer segment)))
+ (make-static-vector (length buffer)
+ :element-type '(unsigned-byte 8)
+ :initial-contents buffer)))))
projects / sbcl.git / blobdiff