valgrind/valgrind-3.14.0-transform-popcount64-ctznat64.patch
Mark Wielaard b3eda9b80b 3.14.0-4 gcc ppc64le inlined memcmp vs memcheck (#1652926)
- Add valgrind-3.14.0-get_otrack_shadow_offset_wrk-ppc.patch,
  valgrind-3.14.0-new-strlen-IROps.patch,
  valgrind-3.14.0-ppc-instr-new-IROps.patch,
  valgrind-3.14.0-memcheck-new-IROps.patch,
  valgrind-3.14.0-ppc-frontend-new-IROps.patch,
  valgrind-3.14.0-transform-popcount64-ctznat64.patch and
  valgrind-3.14.0-enable-ppc-Iop_Sar_Shr8.patch (#1652926)
2018-11-23 22:31:07 +01:00

83 lines
2.7 KiB
Diff

commit cb5d7e047598bff6d0f1d707a70d9fb1a1c7f0e2
Author: Julian Seward <jseward@acm.org>
Date: Tue Nov 20 11:46:55 2018 +0100
VEX/priv/ir_opt.c
fold_Expr: transform PopCount64(And64(Add64(x,-1),Not64(x))) into CtzNat64(x).
This is part of the fix for bug 386945.
diff --git a/VEX/priv/ir_opt.c b/VEX/priv/ir_opt.c
index f40870b..23964be 100644
--- a/VEX/priv/ir_opt.c
+++ b/VEX/priv/ir_opt.c
@@ -1377,6 +1377,8 @@ static IRExpr* fold_Expr ( IRExpr** env, IRExpr* e )
case Iex_Unop:
/* UNARY ops */
if (e->Iex.Unop.arg->tag == Iex_Const) {
+
+ /* cases where the arg is a const */
switch (e->Iex.Unop.op) {
case Iop_1Uto8:
e2 = IRExpr_Const(IRConst_U8(toUChar(
@@ -1690,8 +1692,56 @@ static IRExpr* fold_Expr ( IRExpr** env, IRExpr* e )
default:
goto unhandled;
- }
- }
+ } // switch (e->Iex.Unop.op)
+
+ } else {
+
+ /* other cases (identities, etc) */
+ switch (e->Iex.Unop.op) {
+ case Iop_PopCount64: {
+ // PopCount64( And64( Add64(x,-1), Not64(x) ) ) ==> CtzNat64(x)
+ // bindings:
+ // a1:And64( a11:Add64(a111:x,a112:-1), a12:Not64(a121:x) )
+ IRExpr* a1 = chase(env, e->Iex.Unop.arg);
+ if (!a1)
+ goto nomatch;
+ if (a1->tag != Iex_Binop || a1->Iex.Binop.op != Iop_And64)
+ goto nomatch;
+ // a1 is established
+ IRExpr* a11 = chase(env, a1->Iex.Binop.arg1);
+ if (!a11)
+ goto nomatch;
+ if (a11->tag != Iex_Binop || a11->Iex.Binop.op != Iop_Add64)
+ goto nomatch;
+ // a11 is established
+ IRExpr* a12 = chase(env, a1->Iex.Binop.arg2);
+ if (!a12)
+ goto nomatch;
+ if (a12->tag != Iex_Unop || a12->Iex.Unop.op != Iop_Not64)
+ goto nomatch;
+ // a12 is established
+ IRExpr* a111 = a11->Iex.Binop.arg1;
+ IRExpr* a112 = chase(env, a11->Iex.Binop.arg2);
+ IRExpr* a121 = a12->Iex.Unop.arg;
+ if (!a111 || !a112 || !a121)
+ goto nomatch;
+ // a111 and a121 need to be the same temp.
+ if (!eqIRAtom(a111, a121))
+ goto nomatch;
+ // Finally, a112 must be a 64-bit version of -1.
+ if (!isOnesU(a112))
+ goto nomatch;
+ // Match established. Transform.
+ e2 = IRExpr_Unop(Iop_CtzNat64, a111);
+ break;
+ nomatch:
+ break;
+ }
+ default:
+ break;
+ } // switch (e->Iex.Unop.op)
+
+ } // if (e->Iex.Unop.arg->tag == Iex_Const)
break;
case Iex_Binop: