From: Simon Scherer <[email protected]> FSTP ST(i) copies the value in ST(0) into ST(i) and then pops the register stack. ST(i) should end up marked valid in the FPU tag word and the old ST(0) should end up marked empty.
helper_fmov_STN_ST0() copies the value into ST(i) but never touches its tag. So if ST(i) happened to be tagged empty beforehand, it is still wrongly tagged empty afterwards. Mark the destination tag to valid in helper_fmov_STN_ST0(). This also fixes FST ST(i), which shares the same helper. Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/4400 Signed-off-by: Simon Scherer <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Paolo Bonzini <[email protected]> --- target/i386/tcg/fpu_helper.c | 1 + 1 file changed, 1 insertion(+) diff --git a/target/i386/tcg/fpu_helper.c b/target/i386/tcg/fpu_helper.c index df16c54c208..f42448ab206 100644 --- a/target/i386/tcg/fpu_helper.c +++ b/target/i386/tcg/fpu_helper.c @@ -510,6 +510,7 @@ void helper_fmov_ST0_STN(CPUX86State *env, int st_index) void helper_fmov_STN_ST0(CPUX86State *env, int st_index) { ST(st_index) = ST0; + env->fptags[(env->fpstt + st_index) & 7] = 0; } void helper_fxchg_ST0_STN(CPUX86State *env, int st_index) -- 2.55.0
