Assorted changes to reduce stack and heap requirements when compiling very big functions.

git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2151 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e

2 files changed, 24 insertions, 6 deletions

diff --git a/arm/Asmgen.v b/arm/Asmgen.v
index c7d7712..d158c77 100644
--- a/arm/Asmgen.v
+++ b/arm/Asmgen.v
@@ -593,7 +593,7 @@ Definition transl_instr (f: Mach.function) (i: Mach.instruction)
 
 (** Translation of a code sequence *)
 
-Definition r10_is_parent (before: bool) (i: Mach.instruction) : bool :=
+Definition it1_is_parent (before: bool) (i: Mach.instruction) : bool :=
   match i with
   | Msetstack src ofs ty => before
   | Mgetparam ofs ty dst => negb (mreg_eq dst IT1)
@@ -601,14 +601,32 @@ Definition r10_is_parent (before: bool) (i: Mach.instruction) : bool :=
   | _ => false
   end.
 
-Fixpoint transl_code (f: Mach.function) (il: list Mach.instruction)  (r10p: bool) :=
+(** This is the naive definition that we no longer use because it
+  is not tail-recursive.  It is kept as specification. *)
+
+Fixpoint transl_code (f: Mach.function) (il: list Mach.instruction) (it1p: bool) :=
   match il with
   | nil => OK nil
   | i1 :: il' =>
-      do k <- transl_code f il' (r10_is_parent r10p i1);
-      transl_instr f i1 r10p k
+      do k <- transl_code f il' (it1_is_parent it1p i1);
+      transl_instr f i1 it1p k
   end.
 
+(** This is an equivalent definition in continuation-passing style
+  that runs in constant stack space. *)
+
+Fixpoint transl_code_rec (f: Mach.function) (il: list Mach.instruction)
+                         (it1p: bool) (k: code -> res code) :=
+  match il with
+  | nil => k nil
+  | i1 :: il' =>
+      transl_code_rec f il' (it1_is_parent it1p i1)
+        (fun c1 => do c2 <- transl_instr f i1 it1p c1; k c2)
+  end.
+
+Definition transl_code' (f: Mach.function) (il: list Mach.instruction) (it1p: bool) :=
+  transl_code_rec f il it1p (fun c => OK c).
+
 (** Translation of a whole function.  Note that we must check
   that the generated code contains less than [2^32] instructions,
   otherwise the offset part of the [PC] code pointer could wrap
diff --git a/arm/Asmgenproof.v b/arm/Asmgenproof.v
index 0760eb0..986d474 100644
--- a/arm/Asmgenproof.v
+++ b/arm/Asmgenproof.v
@@ -451,7 +451,7 @@ Lemma exec_straight_steps:
    exists rs2,
        exec_straight tge tf c rs1 m1' k rs2 m2'
     /\ agree ms2 sp rs2
-    /\ (r10_is_parent ep i = true -> rs2#IR10 = parent_sp s)) ->
+    /\ (it1_is_parent ep i = true -> rs2#IR10 = parent_sp s)) ->
   exists st',
   plus step tge (State rs1 m1') E0 st' /\
   match_states (Mach.State s fb sp c ms2 m2) st'.
@@ -470,7 +470,7 @@ Lemma exec_straight_steps_goto:
   Genv.find_funct_ptr ge fb = Some (Internal f) ->
   Mach.find_label lbl f.(Mach.fn_code) = Some c' ->
   transl_code_at_pc ge (rs1 PC) fb f (i :: c) ep tf tc ->
-  r10_is_parent ep i = false ->
+  it1_is_parent ep i = false ->
   (forall k c (TR: transl_instr f i ep k = OK c),
    exists jmp, exists k', exists rs2,
        exec_straight tge tf c rs1 m1' (jmp :: k') rs2 m2'