From: Julian Seward <jseward@acm.org>
Date: Wed, 19 Oct 2016 16:57:11 +0000 (+0000)
Subject: Allow early writeback of SP base register in "strd rD, [sp, #-16]" so
X-Git-Tag: svn/VALGRIND_3_12_0^2^2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e8ef904dedb698940fb3ac39acf332ee119f81ee;p=thirdparty%2Fvalgrind.git

Allow early writeback of SP base register in "strd rD, [sp, #-16]" so
as to avoid Memcheck complaining about writes below SP.  Previously
this was allowed only for the #-8 case.  n-i-bz.


git-svn-id: svn://svn.valgrind.org/vex/trunk@3276
---

diff --git a/VEX/priv/guest_arm_toIR.c b/VEX/priv/guest_arm_toIR.c
index 4b571070b9..ef5a79b263 100644
--- a/VEX/priv/guest_arm_toIR.c
+++ b/VEX/priv/guest_arm_toIR.c
@@ -17431,15 +17431,17 @@ DisResult disInstr_ARM_WRK (
         ignore alignment issues for the time being. */
 
      /* For almost all cases, we do the writeback after the transfers.
-        However, that leaves the stack "uncovered" in this case:
+        However, that leaves the stack "uncovered" in cases like:
            strd    rD, [sp, #-8]
+           strd    rD, [sp, #-16]
         In which case, do the writeback to SP now, instead of later.
         This is bad in that it makes the insn non-restartable if the
         accesses fault, but at least keeps Memcheck happy. */
      Bool writeback_already_done = False;
      if (bS == 1 /*store*/ && summary == (2 | 16)
          && rN == 13 && rN != rD && rN != rD+1
-         && bU == 0/*minus*/ && imm8 == 8) {
+         && bU == 0/*minus*/
+         && (imm8 == 8 || imm8 == 16)) {
         putIRegA( rN, mkexpr(eaT), condT, Ijk_Boring );
         writeback_already_done = True;
      }
@@ -21521,15 +21523,17 @@ DisResult disInstr_THUMB_WRK (
          IRTemp transAddr = bP == 1 ? postAddr : preAddr;
 
          /* For almost all cases, we do the writeback after the transfers.
-            However, that leaves the stack "uncovered" in this case:
+            However, that leaves the stack "uncovered" in cases like:
                strd    rD, [sp, #-8]
+               strd    rD, [sp, #-16]
             In which case, do the writeback to SP now, instead of later.
             This is bad in that it makes the insn non-restartable if the
             accesses fault, but at least keeps Memcheck happy. */
          Bool writeback_already_done = False;
          if (bL == 0/*store*/ && bW == 1/*wb*/
              && rN == 13 && rN != rT && rN != rT2
-             && bU == 0/*minus*/ && (imm8 << 2) == 8) {
+             && bU == 0/*minus*/
+             && ((imm8 << 2) == 8 || (imm8 << 2) == 16)) {
             putIRegT(rN, mkexpr(postAddr), condT);
             writeback_already_done = True;
          }