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[1/2] tcg: add dup_const_tl wrapper

Message ID 20210928205450.4121269-1-philipp.tomsich@vrull.eu
State New
Headers show
Series [1/2] tcg: add dup_const_tl wrapper | expand

Commit Message

Philipp Tomsich Sept. 28, 2021, 8:54 p.m. UTC
dup_const always generates a uint64_t, which may exceed the size of a
target_long (generating warnings with recent-enough compilers).

To ensure that we can use dup_const both for 64bit and 32bit targets,
this adds dup_const_tl, which wraps dup_const and legalises the
truncation to target_long by casting it to target_long.

Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>

---

 include/tcg/tcg.h | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Richard Henderson Oct. 3, 2021, 5:30 p.m. UTC | #1
On 9/28/21 4:54 PM, Philipp Tomsich wrote:
> dup_const always generates a uint64_t, which may exceed the size of a
> target_long (generating warnings with recent-enough compilers).
> 
> To ensure that we can use dup_const both for 64bit and 32bit targets,
> this adds dup_const_tl, which wraps dup_const and legalises the
> truncation to target_long by casting it to target_long.
> 
> Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
> 
> ---
> 
>   include/tcg/tcg.h | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h
> index 44ccd86f3e..8f8a209600 100644
> --- a/include/tcg/tcg.h
> +++ b/include/tcg/tcg.h
> @@ -1272,6 +1272,11 @@ uint64_t dup_const(unsigned vece, uint64_t c);
>           : (qemu_build_not_reached_always(), 0))                    \
>        : dup_const(VECE, C))
>   
> +static inline target_long dup_const_tl(unsigned vece, uint64_t c)
> +{
> +    return (target_long)dup_const(vece, c);
> +}

While this works, it avoids the qemu_build_not_reached() sanity check within dup_const.  I 
think perhaps this should be like

#if TARGET_LONG_BITS == 64
# define dup_const_tl  dup_const
#else
# define dup_const_tl(VECE, C) \
    ... stuff, excluding the MO_64 case
    ... using 32-bit multiplier constants
    ... using (uint32_t)(dup_const)(VECE, C) at the end
#endif


r~
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Patch

diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h
index 44ccd86f3e..8f8a209600 100644
--- a/include/tcg/tcg.h
+++ b/include/tcg/tcg.h
@@ -1272,6 +1272,11 @@  uint64_t dup_const(unsigned vece, uint64_t c);
         : (qemu_build_not_reached_always(), 0))                    \
      : dup_const(VECE, C))
 
+static inline target_long dup_const_tl(unsigned vece, uint64_t c)
+{
+    return (target_long)dup_const(vece, c);
+}
+
 /*
  * Memory helpers that will be used by TCG generated code.
  */