| Message ID | 1437755447-10537-11-git-send-email-aurelien@aurel32.net |
|---|---|
| State | New |
| Headers | show |
Aurelien Jarno <aurelien@aurel32.net> writes: > Cc: Richard Henderson <rth@twiddle.net> > Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> > --- > tcg/README | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/tcg/README b/tcg/README > index 61b3899..a22f251 100644 > --- a/tcg/README > +++ b/tcg/README > @@ -466,13 +466,25 @@ On a 32 bit target, all 64 bit operations are converted to 32 bits. A > few specific operations must be implemented to allow it (see add2_i32, > sub2_i32, brcond2_i32). > > +On a 64 bit target, the values are transfered between 32 and 64-bit > +registers using the following ops: > +- trunc_shr_i64_i32 > +- ext_i32_i64 > +- extu_i32_i64 > + > +They ensure that the values are correctly truncated or extended when > +moved from a 32-bit to a 64-bit register or vice-versa. Note that the > +trunc_shr_i64_i32 is an optional op. It is not necessary to implement > +it if all the following conditions are met: > +- 64-bit registers can hold 32-bit values > +- 32-bit values in a 64-bit register do not need to stay zero or > + sign extended > +- all 32-bit TCG ops ignore the high part of 64-bit registers > + > Floating point operations are not supported in this version. A > previous incarnation of the code generator had full support of them, > but it is better to concentrate on integer operations first. > > -On a 64 bit target, no assumption is made in TCG about the storage of > -the 32 bit values in 64 bit registers. > - > 4.2) Constraints > > GCC like constraints are used to define the constraints of every I would include patches to the README with the respective patches that introduced the changes. It is basically an extended comment ;-)
diff --git a/tcg/README b/tcg/README index 61b3899..a22f251 100644 --- a/tcg/README +++ b/tcg/README @@ -466,13 +466,25 @@ On a 32 bit target, all 64 bit operations are converted to 32 bits. A few specific operations must be implemented to allow it (see add2_i32, sub2_i32, brcond2_i32). +On a 64 bit target, the values are transfered between 32 and 64-bit +registers using the following ops: +- trunc_shr_i64_i32 +- ext_i32_i64 +- extu_i32_i64 + +They ensure that the values are correctly truncated or extended when +moved from a 32-bit to a 64-bit register or vice-versa. Note that the +trunc_shr_i64_i32 is an optional op. It is not necessary to implement +it if all the following conditions are met: +- 64-bit registers can hold 32-bit values +- 32-bit values in a 64-bit register do not need to stay zero or + sign extended +- all 32-bit TCG ops ignore the high part of 64-bit registers + Floating point operations are not supported in this version. A previous incarnation of the code generator had full support of them, but it is better to concentrate on integer operations first. -On a 64 bit target, no assumption is made in TCG about the storage of -the 32 bit values in 64 bit registers. - 4.2) Constraints GCC like constraints are used to define the constraints of every
Cc: Richard Henderson <rth@twiddle.net> Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> --- tcg/README | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)