Theory Effect

theory Effect
imports JVMType JVMExceptions
(*  Title:      HOL/MicroJava/BV/Effect.thy
Author: Gerwin Klein
Copyright 2000 Technische Universitaet Muenchen
*)


header {* \isaheader{Effect of Instructions on the State Type} *}

theory Effect
imports JVMType "../JVM/JVMExceptions"
begin

type_synonym succ_type = "(p_count × state_type option) list"

text {* Program counter of successor instructions: *}
primrec succs :: "instr => p_count => p_count list" where
"succs (Load idx) pc = [pc+1]"
| "succs (Store idx) pc = [pc+1]"
| "succs (LitPush v) pc = [pc+1]"
| "succs (Getfield F C) pc = [pc+1]"
| "succs (Putfield F C) pc = [pc+1]"
| "succs (New C) pc = [pc+1]"
| "succs (Checkcast C) pc = [pc+1]"
| "succs Pop pc = [pc+1]"
| "succs Dup pc = [pc+1]"
| "succs Dup_x1 pc = [pc+1]"
| "succs Dup_x2 pc = [pc+1]"
| "succs Swap pc = [pc+1]"
| "succs IAdd pc = [pc+1]"
| "succs (Ifcmpeq b) pc = [pc+1, nat (int pc + b)]"
| "succs (Goto b) pc = [nat (int pc + b)]"
| "succs Return pc = [pc]"
| "succs (Invoke C mn fpTs) pc = [pc+1]"
| "succs Throw pc = [pc]"

text "Effect of instruction on the state type:"

fun eff' :: "instr × jvm_prog × state_type => state_type"
where
"eff' (Load idx, G, (ST, LT)) = (ok_val (LT ! idx) # ST, LT)" |
"eff' (Store idx, G, (ts#ST, LT)) = (ST, LT[idx:= OK ts])" |
"eff' (LitPush v, G, (ST, LT)) = (the (typeof (λv. None) v) # ST, LT)" |
"eff' (Getfield F C, G, (oT#ST, LT)) = (snd (the (field (G,C) F)) # ST, LT)" |
"eff' (Putfield F C, G, (vT#oT#ST, LT)) = (ST,LT)" |
"eff' (New C, G, (ST,LT)) = (Class C # ST, LT)" |
"eff' (Checkcast C, G, (RefT rt#ST,LT)) = (Class C # ST,LT)" |
"eff' (Pop, G, (ts#ST,LT)) = (ST,LT)" |
"eff' (Dup, G, (ts#ST,LT)) = (ts#ts#ST,LT)" |
"eff' (Dup_x1, G, (ts1#ts2#ST,LT)) = (ts1#ts2#ts1#ST,LT)" |
"eff' (Dup_x2, G, (ts1#ts2#ts3#ST,LT)) = (ts1#ts2#ts3#ts1#ST,LT)" |
"eff' (Swap, G, (ts1#ts2#ST,LT)) = (ts2#ts1#ST,LT)" |
"eff' (IAdd, G, (PrimT Integer#PrimT Integer#ST,LT))
= (PrimT Integer#ST,LT)"
|
"eff' (Ifcmpeq b, G, (ts1#ts2#ST,LT)) = (ST,LT)" |
"eff' (Goto b, G, s) = s" |
-- "Return has no successor instruction in the same method"
"eff' (Return, G, s) = s" |
-- "Throw always terminates abruptly"
"eff' (Throw, G, s) = s" |
"eff' (Invoke C mn fpTs, G, (ST,LT)) = (let ST' = drop (length fpTs) ST
in (fst (snd (the (method (G,C) (mn,fpTs))))#(tl ST'),LT))"




primrec match_any :: "jvm_prog => p_count => exception_table => cname list" where
"match_any G pc [] = []"
| "match_any G pc (e#es) = (let (start_pc, end_pc, handler_pc, catch_type) = e;
es' = match_any G pc es
in
if start_pc <= pc ∧ pc < end_pc then catch_type#es' else es')"


primrec match :: "jvm_prog => xcpt => p_count => exception_table => cname list" where
"match G X pc [] = []"
| "match G X pc (e#es) =
(if match_exception_entry G (Xcpt X) pc e then [Xcpt X] else match G X pc es)"


lemma match_some_entry:
"match G X pc et = (if ∃e ∈ set et. match_exception_entry G (Xcpt X) pc e then [Xcpt X] else [])"
by (induct et) auto

fun
xcpt_names :: "instr × jvm_prog × p_count × exception_table => cname list"
where
"xcpt_names (Getfield F C, G, pc, et) = match G NullPointer pc et"
| "xcpt_names (Putfield F C, G, pc, et) = match G NullPointer pc et"
| "xcpt_names (New C, G, pc, et) = match G OutOfMemory pc et"
| "xcpt_names (Checkcast C, G, pc, et) = match G ClassCast pc et"
| "xcpt_names (Throw, G, pc, et) = match_any G pc et"
| "xcpt_names (Invoke C m p, G, pc, et) = match_any G pc et"
| "xcpt_names (i, G, pc, et) = []"


definition xcpt_eff :: "instr => jvm_prog => p_count => state_type option => exception_table => succ_type" where
"xcpt_eff i G pc s et ==
map (λC. (the (match_exception_table G C pc et), case s of None => None | Some s' => Some ([Class C], snd s')))
(xcpt_names (i,G,pc,et))"


definition norm_eff :: "instr => jvm_prog => state_type option => state_type option" where
"norm_eff i G == Option.map (λs. eff' (i,G,s))"

definition eff :: "instr => jvm_prog => p_count => exception_table => state_type option => succ_type" where
"eff i G pc et s == (map (λpc'. (pc',norm_eff i G s)) (succs i pc)) @ (xcpt_eff i G pc s et)"

definition isPrimT :: "ty => bool" where
"isPrimT T == case T of PrimT T' => True | RefT T' => False"

definition isRefT :: "ty => bool" where
"isRefT T == case T of PrimT T' => False | RefT T' => True"

lemma isPrimT [simp]:
"isPrimT T = (∃T'. T = PrimT T')" by (simp add: isPrimT_def split: ty.splits)

lemma isRefT [simp]:
"isRefT T = (∃T'. T = RefT T')" by (simp add: isRefT_def split: ty.splits)


lemma "list_all2 P a b ==> ∀(x,y) ∈ set (zip a b). P x y"
by (simp add: list_all2_def)


text "Conditions under which eff is applicable:"

fun
app' :: "instr × jvm_prog × p_count × nat × ty × state_type => bool"
where
"app' (Load idx, G, pc, maxs, rT, s) =
(idx < length (snd s) ∧ (snd s) ! idx ≠ Err ∧ length (fst s) < maxs)"
|
"app' (Store idx, G, pc, maxs, rT, (ts#ST, LT)) =
(idx < length LT)"
|
"app' (LitPush v, G, pc, maxs, rT, s) =
(length (fst s) < maxs ∧ typeof (λt. None) v ≠ None)"
|
"app' (Getfield F C, G, pc, maxs, rT, (oT#ST, LT)) =
(is_class G C ∧ field (G,C) F ≠ None ∧ fst (the (field (G,C) F)) = C ∧
G \<turnstile> oT \<preceq> (Class C))"
|
"app' (Putfield F C, G, pc, maxs, rT, (vT#oT#ST, LT)) =
(is_class G C ∧ field (G,C) F ≠ None ∧ fst (the (field (G,C) F)) = C ∧
G \<turnstile> oT \<preceq> (Class C) ∧ G \<turnstile> vT \<preceq> (snd (the (field (G,C) F))))"
|
"app' (New C, G, pc, maxs, rT, s) =
(is_class G C ∧ length (fst s) < maxs)"
|
"app' (Checkcast C, G, pc, maxs, rT, (RefT rt#ST,LT)) =
(is_class G C)"
|
"app' (Pop, G, pc, maxs, rT, (ts#ST,LT)) =
True"
|
"app' (Dup, G, pc, maxs, rT, (ts#ST,LT)) =
(1+length ST < maxs)"
|
"app' (Dup_x1, G, pc, maxs, rT, (ts1#ts2#ST,LT)) =
(2+length ST < maxs)"
|
"app' (Dup_x2, G, pc, maxs, rT, (ts1#ts2#ts3#ST,LT)) =
(3+length ST < maxs)"
|
"app' (Swap, G, pc, maxs, rT, (ts1#ts2#ST,LT)) =
True"
|
"app' (IAdd, G, pc, maxs, rT, (PrimT Integer#PrimT Integer#ST,LT)) =
True"
|
"app' (Ifcmpeq b, G, pc, maxs, rT, (ts#ts'#ST,LT)) =
(0 ≤ int pc + b ∧ (isPrimT ts ∧ ts' = ts ∨ isRefT ts ∧ isRefT ts'))"
|
"app' (Goto b, G, pc, maxs, rT, s) =
(0 ≤ int pc + b)"
|
"app' (Return, G, pc, maxs, rT, (T#ST,LT)) =
(G \<turnstile> T \<preceq> rT)"
|
"app' (Throw, G, pc, maxs, rT, (T#ST,LT)) =
isRefT T"
|
"app' (Invoke C mn fpTs, G, pc, maxs, rT, s) =
(length fpTs < length (fst s) ∧
(let apTs = rev (take (length fpTs) (fst s));
X = hd (drop (length fpTs) (fst s))
in
G \<turnstile> X \<preceq> Class C ∧ is_class G C ∧ method (G,C) (mn,fpTs) ≠ None ∧
list_all2 (λx y. G \<turnstile> x \<preceq> y) apTs fpTs))"
|

"app' (i,G, pc,maxs,rT,s) = False"

definition xcpt_app :: "instr => jvm_prog => nat => exception_table => bool" where
"xcpt_app i G pc et ≡ ∀C∈set(xcpt_names (i,G,pc,et)). is_class G C"

definition app :: "instr => jvm_prog => nat => ty => nat => exception_table => state_type option => bool" where
"app i G maxs rT pc et s == case s of None => True | Some t => app' (i,G,pc,maxs,rT,t) ∧ xcpt_app i G pc et"


lemma match_any_match_table:
"C ∈ set (match_any G pc et) ==> match_exception_table G C pc et ≠ None"
apply (induct et)
apply simp
apply simp
apply clarify
apply (simp split: split_if_asm)
apply (auto simp add: match_exception_entry_def)
done

lemma match_X_match_table:
"C ∈ set (match G X pc et) ==> match_exception_table G C pc et ≠ None"
apply (induct et)
apply simp
apply (simp split: split_if_asm)
done

lemma xcpt_names_in_et:
"C ∈ set (xcpt_names (i,G,pc,et)) ==>
∃e ∈ set et. the (match_exception_table G C pc et) = fst (snd (snd e))"

apply (cases i)
apply (auto dest!: match_any_match_table match_X_match_table
dest: match_exception_table_in_et)
done


lemma 1: "2 < length a ==> (∃l l' l'' ls. a = l#l'#l''#ls)"
proof (cases a)
fix x xs assume "a = x#xs" "2 < length a"
thus ?thesis by - (cases xs, simp, cases "tl xs", auto)
qed auto

lemma 2: "¬(2 < length a) ==> a = [] ∨ (∃ l. a = [l]) ∨ (∃ l l'. a = [l,l'])"
proof -
assume "¬(2 < length a)"
hence "length a < (Suc (Suc (Suc 0)))" by simp
hence * : "length a = 0 ∨ length a = Suc 0 ∨ length a = Suc (Suc 0)"
by (auto simp add: less_Suc_eq)

{
fix x
assume "length x = Suc 0"
hence "∃ l. x = [l]" by (cases x) auto
} note 0 = this

have "length a = Suc (Suc 0) ==> ∃l l'. a = [l,l']" by (cases a) (auto dest: 0)
with * show ?thesis by (auto dest: 0)
qed

lemmas [simp] = app_def xcpt_app_def

text {*
\medskip
simp rules for @{term app}
*}

lemma appNone[simp]: "app i G maxs rT pc et None = True" by simp


lemma appLoad[simp]:
"(app (Load idx) G maxs rT pc et (Some s)) = (∃ST LT. s = (ST,LT) ∧ idx < length LT ∧ LT!idx ≠ Err ∧ length ST < maxs)"
by (cases s, simp)

lemma appStore[simp]:
"(app (Store idx) G maxs rT pc et (Some s)) = (∃ts ST LT. s = (ts#ST,LT) ∧ idx < length LT)"
by (cases s, cases "2 < length (fst s)", auto dest: 1 2)

lemma appLitPush[simp]:
"(app (LitPush v) G maxs rT pc et (Some s)) = (∃ST LT. s = (ST,LT) ∧ length ST < maxs ∧ typeof (λv. None) v ≠ None)"
by (cases s, simp)

lemma appGetField[simp]:
"(app (Getfield F C) G maxs rT pc et (Some s)) =
(∃ oT vT ST LT. s = (oT#ST, LT) ∧ is_class G C ∧
field (G,C) F = Some (C,vT) ∧ G \<turnstile> oT \<preceq> (Class C) ∧ (∀x ∈ set (match G NullPointer pc et). is_class G x))"

by (cases s, cases "2 <length (fst s)", auto dest!: 1 2)

lemma appPutField[simp]:
"(app (Putfield F C) G maxs rT pc et (Some s)) =
(∃ vT vT' oT ST LT. s = (vT#oT#ST, LT) ∧ is_class G C ∧
field (G,C) F = Some (C, vT') ∧ G \<turnstile> oT \<preceq> (Class C) ∧ G \<turnstile> vT \<preceq> vT' ∧
(∀x ∈ set (match G NullPointer pc et). is_class G x))"

by (cases s, cases "2 <length (fst s)", auto dest!: 1 2)

lemma appNew[simp]:
"(app (New C) G maxs rT pc et (Some s)) =
(∃ST LT. s=(ST,LT) ∧ is_class G C ∧ length ST < maxs ∧
(∀x ∈ set (match G OutOfMemory pc et). is_class G x))"

by (cases s, simp)

lemma appCheckcast[simp]:
"(app (Checkcast C) G maxs rT pc et (Some s)) =
(∃rT ST LT. s = (RefT rT#ST,LT) ∧ is_class G C ∧
(∀x ∈ set (match G ClassCast pc et). is_class G x))"

by (cases s, cases "fst s", simp) (cases "hd (fst s)", auto)

lemma appPop[simp]:
"(app Pop G maxs rT pc et (Some s)) = (∃ts ST LT. s = (ts#ST,LT))"
by (cases s, cases "2 <length (fst s)", auto dest: 1 2)


lemma appDup[simp]:
"(app Dup G maxs rT pc et (Some s)) = (∃ts ST LT. s = (ts#ST,LT) ∧ 1+length ST < maxs)"
by (cases s, cases "2 <length (fst s)", auto dest: 1 2)


lemma appDup_x1[simp]:
"(app Dup_x1 G maxs rT pc et (Some s)) = (∃ts1 ts2 ST LT. s = (ts1#ts2#ST,LT) ∧ 2+length ST < maxs)"
by (cases s, cases "2 <length (fst s)", auto dest: 1 2)


lemma appDup_x2[simp]:
"(app Dup_x2 G maxs rT pc et (Some s)) = (∃ts1 ts2 ts3 ST LT. s = (ts1#ts2#ts3#ST,LT) ∧ 3+length ST < maxs)"
by (cases s, cases "2 <length (fst s)", auto dest: 1 2)


lemma appSwap[simp]:
"app Swap G maxs rT pc et (Some s) = (∃ts1 ts2 ST LT. s = (ts1#ts2#ST,LT))"
by (cases s, cases "2 <length (fst s)") (auto dest: 1 2)


lemma appIAdd[simp]:
"app IAdd G maxs rT pc et (Some s) = (∃ ST LT. s = (PrimT Integer#PrimT Integer#ST,LT))"
(is "?app s = ?P s")
proof (cases s)
case (Pair a b)
have "?app (a,b) = ?P (a,b)"
proof (cases a)
fix t ts assume a: "a = t#ts"
show ?thesis
proof (cases t)
fix p assume p: "t = PrimT p"
show ?thesis
proof (cases p)
assume ip: "p = Integer"
show ?thesis
proof (cases ts)
fix t' ts' assume t': "ts = t' # ts'"
show ?thesis
proof (cases t')
fix p' assume "t' = PrimT p'"
with t' ip p a
show ?thesis by (cases p') auto
qed (auto simp add: a p ip t')
qed (auto simp add: a p ip)
qed (auto simp add: a p)
qed (auto simp add: a)
qed auto
with Pair show ?thesis by simp
qed


lemma appIfcmpeq[simp]:
"app (Ifcmpeq b) G maxs rT pc et (Some s) =
(∃ts1 ts2 ST LT. s = (ts1#ts2#ST,LT) ∧ 0 ≤ int pc + b ∧
((∃ p. ts1 = PrimT p ∧ ts2 = PrimT p) ∨ (∃r r'. ts1 = RefT r ∧ ts2 = RefT r')))"

by (cases s, cases "2 <length (fst s)", auto dest!: 1 2)

lemma appReturn[simp]:
"app Return G maxs rT pc et (Some s) = (∃T ST LT. s = (T#ST,LT) ∧ (G \<turnstile> T \<preceq> rT))"
by (cases s, cases "2 <length (fst s)", auto dest: 1 2)

lemma appGoto[simp]:
"app (Goto b) G maxs rT pc et (Some s) = (0 ≤ int pc + b)"
by simp

lemma appThrow[simp]:
"app Throw G maxs rT pc et (Some s) =
(∃T ST LT r. s=(T#ST,LT) ∧ T = RefT r ∧ (∀C ∈ set (match_any G pc et). is_class G C))"

by (cases s, cases "2 < length (fst s)", auto dest: 1 2)

lemma appInvoke[simp]:
"app (Invoke C mn fpTs) G maxs rT pc et (Some s) = (∃apTs X ST LT mD' rT' b'.
s = ((rev apTs) @ (X # ST), LT) ∧ length apTs = length fpTs ∧ is_class G C ∧
G \<turnstile> X \<preceq> Class C ∧ (∀(aT,fT)∈set(zip apTs fpTs). G \<turnstile> aT \<preceq> fT) ∧
method (G,C) (mn,fpTs) = Some (mD', rT', b') ∧
(∀C ∈ set (match_any G pc et). is_class G C))"
(is "?app s = ?P s")
proof (cases s)
note list_all2_def [simp]
case (Pair a b)
have "?app (a,b) ==> ?P (a,b)"
proof -
assume app: "?app (a,b)"
hence "a = (rev (rev (take (length fpTs) a))) @ (drop (length fpTs) a) ∧
length fpTs < length a"
(is "?a ∧ ?l")
by auto
hence "?a ∧ 0 < length (drop (length fpTs) a)" (is "?a ∧ ?l")
by auto
hence "?a ∧ ?l ∧ length (rev (take (length fpTs) a)) = length fpTs"
by (auto)
hence "∃apTs ST. a = rev apTs @ ST ∧ length apTs = length fpTs ∧ 0 < length ST"
by blast
hence "∃apTs ST. a = rev apTs @ ST ∧ length apTs = length fpTs ∧ ST ≠ []"
by blast
hence "∃apTs ST. a = rev apTs @ ST ∧ length apTs = length fpTs ∧
(∃X ST'. ST = X#ST')"

by (simp add: neq_Nil_conv)
hence "∃apTs X ST. a = rev apTs @ X # ST ∧ length apTs = length fpTs"
by blast
with app
show ?thesis by clarsimp blast
qed
with Pair
have "?app s ==> ?P s" by (simp only:)
moreover
have "?P s ==> ?app s" by (clarsimp simp add: min_max.inf_absorb2)
ultimately
show ?thesis by (rule iffI)
qed

lemma effNone:
"(pc', s') ∈ set (eff i G pc et None) ==> s' = None"
by (auto simp add: eff_def xcpt_eff_def norm_eff_def)


lemma xcpt_app_lemma [code]:
"xcpt_app i G pc et = list_all (is_class G) (xcpt_names (i, G, pc, et))"
by (simp add: list_all_iff)

lemmas [simp del] = app_def xcpt_app_def

end