From d2663a1f9dc73f767afa1c1a59bcc39de775f709 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20B=C3=BChler?= <david.buhler@cea.fr>
Date: Thu, 1 Aug 2019 14:15:01 +0200
Subject: [PATCH] [Eva] Relaxed heuristic for automatic loop unroll.
---
headers/header_spec.txt | 2 ++
.../value/partitioning/auto_loop_unroll.ml | 20 +++++++++++--------
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/headers/header_spec.txt b/headers/header_spec.txt
index d1223e54ced..c6b5f3be4f5 100644
--- a/headers/header_spec.txt
+++ b/headers/header_spec.txt
@@ -1259,6 +1259,8 @@ src/plugins/value/legacy/function_args.ml: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/legacy/function_args.mli: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/register.ml: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/register.mli: CEA_LGPL_OR_PROPRIETARY
+src/plugins/value/partitioning/auto_loop_unroll.ml: CEA_LGPL_OR_PROPRIETARY
+src/plugins/value/partitioning/auto_loop_unroll.mli: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/partitioning/partitioning_parameters.ml: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/partitioning/partitioning_parameters.mli: CEA_LGPL_OR_PROPRIETARY
src/plugins/value/partitioning/per_stmt_slevel.ml: CEA_LGPL_OR_PROPRIETARY
diff --git a/src/plugins/value/partitioning/auto_loop_unroll.ml b/src/plugins/value/partitioning/auto_loop_unroll.ml
index 9620f6e21f7..384533297e5 100644
--- a/src/plugins/value/partitioning/auto_loop_unroll.ml
+++ b/src/plugins/value/partitioning/auto_loop_unroll.ml
@@ -38,10 +38,10 @@
The heuristic is syntactic and limited to the current function: it does not
handle assignment through pointers or function calls.
- Thus, the condition [cond] must only contains direct accesses to variables
+ Thus, the condition [cond] should only contains direct accesses to variables
whose address is never taken (they cannot be modified through pointers). If
- the loop contains a function call, the condition [cond] must not contain any
- global variable (as they may be modified in the function called).
+ the loop contains a function call, the condition [cond] should not contain
+ global variables (as they may be modified in the function called).
A first analyze of the loop gathers all such variables modified within the
loop; all others are constant, and can be evaluated in the loop entry state.
@@ -113,7 +113,7 @@ end
(* The status of a lvalue for the automatic loop unroll heuristic. *)
type var_status =
- | Constant (* The lvalue is constant within the loop. *)
+ | Constant (* The lvalue is probably constant within the loop. *)
| Candidate (* The lvalue is a good candidate for the heuristic:
integer type, access to a varinfo whose address is not taken,
modified within the loop but not in another function called
@@ -134,13 +134,17 @@ let classify loop_effect lval =
| AlignOf _ | AlignOfE _ | AddrOf _ | StartOf _ -> true
and classify_lval = function
| Var varinfo, offset ->
- if varinfo.vaddrof
- || (varinfo.vglob && loop_effect.call)
+ if (varinfo.vglob && loop_effect.call)
|| not (is_const_offset offset)
then Unsuitable
else if Cil_datatype.Varinfo.Set.mem varinfo loop_effect.written_vars
- then if is_integer lval then Candidate else Unsuitable
- else Constant
+ then
+ if is_integer lval && not varinfo.vaddrof then Candidate else Unsuitable
+ else
+ (* If the address of the variable is taken, it could be modified within
+ the loop. We suppose here that this is not the case, but this could
+ lead to some loop unrolling. *)
+ Constant
| Mem _, _ -> Unsuitable (* Pointers are not supported by the heuristic. *)
and is_const_offset = function
| NoOffset -> true
--
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