Functions which modify virtual machine state (such as virtual
registers stored in memory) must not be marked TCG_CALL_NO_WG as that
tells the optimizer that virtual registers values already loaded in
machine registers are still valid, hence discards any changes which
these helpers may have made. This seems to also mean that functions which
set condition codes may also not use this flag

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 target/rx/helper.h | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/target/rx/helper.h b/target/rx/helper.h
index ebb4739474..8cc38b0cb7 100644
--- a/target/rx/helper.h
+++ b/target/rx/helper.h
@@ -4,27 +4,27 @@ DEF_HELPER_1(raise_privilege_violation, noreturn, env)
 DEF_HELPER_1(wait, noreturn, env)
 DEF_HELPER_2(rxint, noreturn, env, i32)
 DEF_HELPER_1(rxbrk, noreturn, env)
-DEF_HELPER_FLAGS_3(fadd, TCG_CALL_NO_WG, f32, env, f32, f32)
-DEF_HELPER_FLAGS_3(fsub, TCG_CALL_NO_WG, f32, env, f32, f32)
-DEF_HELPER_FLAGS_3(fmul, TCG_CALL_NO_WG, f32, env, f32, f32)
-DEF_HELPER_FLAGS_3(fdiv, TCG_CALL_NO_WG, f32, env, f32, f32)
-DEF_HELPER_FLAGS_3(fcmp, TCG_CALL_NO_WG, void, env, f32, f32)
-DEF_HELPER_FLAGS_2(ftoi, TCG_CALL_NO_WG, i32, env, f32)
-DEF_HELPER_FLAGS_2(round, TCG_CALL_NO_WG, i32, env, f32)
-DEF_HELPER_FLAGS_2(itof, TCG_CALL_NO_WG, f32, env, i32)
+DEF_HELPER_3(fadd, f32, env, f32, f32)
+DEF_HELPER_3(fsub, f32, env, f32, f32)
+DEF_HELPER_3(fmul, f32, env, f32, f32)
+DEF_HELPER_3(fdiv, f32, env, f32, f32)
+DEF_HELPER_3(fcmp, void, env, f32, f32)
+DEF_HELPER_2(ftoi, i32, env, f32)
+DEF_HELPER_2(round, i32, env, f32)
+DEF_HELPER_2(itof, f32, env, i32)
 DEF_HELPER_2(set_fpsw, void, env, i32)
-DEF_HELPER_FLAGS_2(racw, TCG_CALL_NO_WG, void, env, i32)
-DEF_HELPER_FLAGS_2(set_psw_rte, TCG_CALL_NO_WG, void, env, i32)
-DEF_HELPER_FLAGS_2(set_psw, TCG_CALL_NO_WG, void, env, i32)
+DEF_HELPER_2(racw, void, env, i32)
+DEF_HELPER_2(set_psw_rte, void, env, i32)
+DEF_HELPER_2(set_psw, void, env, i32)
 DEF_HELPER_1(pack_psw, i32, env)
-DEF_HELPER_FLAGS_3(div, TCG_CALL_NO_WG, i32, env, i32, i32)
-DEF_HELPER_FLAGS_3(divu, TCG_CALL_NO_WG, i32, env, i32, i32)
-DEF_HELPER_FLAGS_1(scmpu, TCG_CALL_NO_WG, void, env)
+DEF_HELPER_3(div, i32, env, i32, i32)
+DEF_HELPER_3(divu, i32, env, i32, i32)
+DEF_HELPER_1(scmpu, void, env)
 DEF_HELPER_1(smovu, void, env)
 DEF_HELPER_1(smovf, void, env)
 DEF_HELPER_1(smovb, void, env)
 DEF_HELPER_2(sstr, void, env, i32)
-DEF_HELPER_FLAGS_2(swhile, TCG_CALL_NO_WG, void, env, i32)
-DEF_HELPER_FLAGS_2(suntil, TCG_CALL_NO_WG, void, env, i32)
-DEF_HELPER_FLAGS_2(rmpa, TCG_CALL_NO_WG, void, env, i32)
+DEF_HELPER_2(swhile, void, env, i32)
+DEF_HELPER_2(suntil, void, env, i32)
+DEF_HELPER_2(rmpa, void, env, i32)
 DEF_HELPER_1(satr, void, env)
-- 
2.47.2

On Tue, 18 Feb 2025 at 21:22, Keith Packard via <qemu-devel@nongnu.org> wrote:
>
> Functions which modify virtual machine state (such as virtual
> registers stored in memory) must not be marked TCG_CALL_NO_WG

More accurately, functions which write to TCG globals.
It's fine for a function which modifies virtual machine
state to be marked TCG_CALL_NO_WG as long as that
virtual machine state isn't stored in a TCG global.

> as that
> tells the optimizer that virtual registers values already loaded in
> machine registers are still valid, hence discards any changes which
> these helpers may have made. This seems to also mean that functions which
> set condition codes may also not use this flag

...because target/rx makes the (sensible) choice to put its
condition codes in TCG globals.

> Signed-off-by: Keith Packard <keithp@keithp.com>
> ---
>  target/rx/helper.h | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM