212353 2009-10-30 05:13:08 +0000 vex amd64->IR: unhandled instruction bytes: 0x48 0xE9 (REX.W JMP) 2010-11-11 19:51:42 +0000 1 1 6 Developer tools valgrind vex 3.5.0 Compiled Sources Linux UNCONFIRMED NOR normal --- 253451 0 mark.hsj jseward 0 oldest_to_newest 852794 0 mark.hsj 2009-10-30 05:13:08 +0000 Attempting to use valgrind on a VHDL simulation compiled to x86_64 code on RHEL 4, I encountered the following message from valgrind: vex amd64->IR: unhandled instruction bytes: 0x48 0xE9 0x2A 0x7 0x0 0x0 ==29986== valgrind: Unrecognised instruction at address 0x686a004. The instruction is REX.W JMP rel32off. VEX does not like the redundant REX.W prefix. I was able to correct the problem by adding the following line to VEX/priv/guest_amd64_toIR.c: --- guest_amd64_toIR.c.orig 2009-08-19 06:37:52.000000000 -0700 +++ guest_amd64_toIR.c 2009-10-29 20:20:58.106941000 -0700 @@ -13941,6 +13941,7 @@ case 0xE9: /* Jv (jump, 16/32 offset) */ if (haveF2orF3(pfx)) goto decode_failure; + if (sz == 8) sz = 4; if (sz != 4) goto decode_failure; /* JRS added 2004 July 11 */ d64 = (guest_RIP_bbstart+delta+sz) + getSDisp(sz,delta);