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]> (cherry picked from commit f2357fdcd984c37fb0f3f64698a38ba1f55fd9c5) Signed-off-by: Michael Tokarev <[email protected]> diff --git a/target/i386/tcg/fpu_helper.c b/target/i386/tcg/fpu_helper.c index 64c5e82a2c4..53b6e612812 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) -- 2.47.3
