From: Julian Seward <jseward@acm.org>
Date: Sun, 7 Nov 2004 00:57:46 +0000 (+0000)
Subject: Install a bogus-literals hack a la old UCode scheme, but do not use
X-Git-Tag: svn/VALGRIND_3_0_1^2~816
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0f9834426ba48645ed7d4e2e136b76074df5d283;p=thirdparty%2Fvalgrind.git

Install a bogus-literals hack a la old UCode scheme, but do not use
it.  Instead, observe that all of the residual errors are from
stpcpy/strnlen in glibc.  Then observe that the redirect mechanism
seems to fail to redirect these to our "safe" equivalents.  Then,
finally realise that the redirect mechanism is defeated by vex's
cross-BB-chasing and specifically by chasing across function call
boundaries.

So, the good news is that giving --vex-guest-chase-thresh=0 makes all
these errors go away.  This should be straightforward to fix properly.



git-svn-id: svn://svn.valgrind.org/vex/trunk@518
---

diff --git a/VEX/head20041019/memcheck/mc_translate.c b/VEX/head20041019/memcheck/mc_translate.c
index 0f885e9b36..4f03b9ed5c 100644
--- a/VEX/head20041019/memcheck/mc_translate.c
+++ b/VEX/head20041019/memcheck/mc_translate.c
@@ -1136,10 +1136,81 @@ void do_shadow_STle ( MCEnv* mce, IRAtom* addr, IRAtom* data )
 /*--- Memcheck main                                        ---*/
 /*------------------------------------------------------------*/
 
+#if 0 /* UNUSED */
+static Bool isBogusAtom ( IRAtom* at )
+{
+   ULong n = 0;
+   IRConst* con;
+   sk_assert(isAtom(at));
+   if (at->tag == Iex_Tmp)
+      return False;
+   sk_assert(at->tag == Iex_Const);
+   con = at->Iex.Const.con;
+   switch (con->tag) {
+      case Ico_U8:  n = (ULong)con->Ico.U8; break;
+      case Ico_U16: n = (ULong)con->Ico.U16; break;
+      case Ico_U32: n = (ULong)con->Ico.U32; break;
+      case Ico_U64: n = (ULong)con->Ico.U64; break;
+      default: ppIRExpr(at); sk_assert(0);
+   }
+   /* VG_(printf)("%llx\n", n); */
+   return (n == 0xFEFEFEFF
+           || n == 0x80808080
+           || n == 0x1010101
+           || n == 1010100);
+}
+
+static Bool checkForBogusLiterals ( /*FLAT*/ IRStmt* st )
+{
+   Int     i;
+   IRExpr* e;
+   switch (st->tag) {
+      case Ist_Tmp:
+         e = st->Ist.Tmp.data;
+         switch (e->tag) {
+            case Iex_Get:
+            case Iex_Tmp:
+               return False;
+            case Iex_Unop: 
+               return isBogusAtom(e->Iex.Unop.arg);
+            case Iex_Binop: 
+               return isBogusAtom(e->Iex.Binop.arg1)
+                      || isBogusAtom(e->Iex.Binop.arg2);
+            case Iex_Mux0X:
+               return isBogusAtom(e->Iex.Mux0X.cond)
+                      || isBogusAtom(e->Iex.Mux0X.expr0)
+                      || isBogusAtom(e->Iex.Mux0X.exprX);
+            case Iex_LDle: 
+               return isBogusAtom(e->Iex.LDle.addr);
+            case Iex_CCall:
+               for (i = 0; e->Iex.CCall.args[i]; i++)
+                  if (isBogusAtom(e->Iex.CCall.args[i]))
+                     return True;
+               return False;
+            default: 
+               goto unhandled;
+         }
+      case Ist_Put:
+         return isBogusAtom(st->Ist.Put.data);
+      case Ist_STle:
+         return isBogusAtom(st->Ist.STle.addr) 
+                || isBogusAtom(st->Ist.STle.data);
+      case Ist_Exit:
+         return isBogusAtom(st->Ist.Exit.cond);
+      default: 
+      unhandled:
+         ppIRStmt(st);
+         VG_(skin_panic)("hasBogusLiterals");
+   }
+}
+#endif /* UNUSED */
+
+
 IRBB* SK_(instrument) ( IRBB* bb_in, VexGuestLayout* layout, IRType hWordTy )
 {
-   Bool verboze = False;
-     //True; 
+   Bool verboze = False;  //True; 
+
+   /* Bool hasBogusLiterals = False; */
 
    Int i, j, first_stmt;
    IRStmt* st;
@@ -1168,6 +1239,17 @@ IRBB* SK_(instrument) ( IRBB* bb_in, VexGuestLayout* layout, IRType hWordTy )
       if (!st) continue;
 
       sk_assert(isFlatIRStmt(st));
+
+      /*
+      if (!hasBogusLiterals) {
+         hasBogusLiterals = checkForBogusLiterals(st);
+         if (hasBogusLiterals) {
+            VG_(printf)("bogus: ");
+            ppIRStmt(st);
+            VG_(printf)("\n");
+         }
+      }
+      */
       first_stmt = bb->stmts_used;
 
       if (verboze) {
@@ -1201,7 +1283,8 @@ IRBB* SK_(instrument) ( IRBB* bb_in, VexGuestLayout* layout, IRType hWordTy )
             break;
 
          case Ist_Exit:
-            complainIfUndefined( &mce, st->Ist.Exit.cond );
+            /* if (!hasBogusLiterals) */
+               complainIfUndefined( &mce, st->Ist.Exit.cond );
             break;
 
          default: