Re: [Qemu-devel] bug in popcnt emulation with some register operand(s)?

[malc]

On Mon, 8 Oct 2012, Andriy Gapon wrote:

> 
> I am running Qemu (plain, no kvm, etc) on an AMD 10h machine that
> provides popcnt instruction.  Qemu advertises availability of pocnt
> to a guest as well.  What I see in the guest that popcnt
> 0x20(%r12),%r8 instruction actually placed its result into %rax.
> With %rdi and %rax operands the instruction worked fine though.
> 
> 

Does following work?

diff --git a/target-i386/translate.c b/target-i386/translate.c
index e896abf..c36cc3e 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -7818,7 +7818,7 @@ static target_ulong disas_insn(DisasContext *s, 
target_ulong pc_start)
             goto illegal_op;
 
         modrm = cpu_ldub_code(cpu_single_env, s->pc++);
-        reg = ((modrm >> 3) & 7);
+        reg = ((modrm >> 3) & 7) | rex_r;
 
         if (s->prefix & PREFIX_DATA)
             ot = OT_WORD;

-- 
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