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digitalmars.D - templates and assembler

reply manu <manu_member pathlink.com> writes:
Hi there!
I´m new to D and quite surprised about all the nice features it provides. So I
started to write some test apps and also tried to write some templates. It all
worked perfect until I wanted to use template identifiers in asm blocks.

consider the following:

/* file - main.d **************************************/
01: template sine(REAL) // where REAL should be one of float,double,real 
02: {
03:     float sine(REAL x)
04:	{
05:	    asm 
06:	    {
07:	        naked		    ; // <- make it naked to get maximum speed
08:		fld REAL ptr[ESP+4] ; // <- critical opcode
09:		fsin		    ;
10:		ret		    ;
11:	    }
12:     }
13: }
14: alias sine!(float) sine_float; // instantiation
/ *****************************************************/
An error occurs when typing the last line, due to the instantiation. It says:

main.d(8): end of instruction

I´ve figured out that it comes because of the REAL in the asm block. I also
tried this for line 08:

08:   fld x

Though this compiles there remains an error at runtime: the program assumes x to
be at a different position on the stack and so just a dump of stack memory is
loaded into the FPU. May this an unfixed bug of the compiler(I´m using dmd)? 

I would be very thankful to everybody who helps me fixing that problem!
Mar 25 2006
parent reply James Dunne <james.jdunne gmail.com> writes:
manu wrote:

 Hi there!
 I´m new to D and quite surprised about all the nice features it provides. So I
 started to write some test apps and also tried to write some templates. It all
 worked perfect until I wanted to use template identifiers in asm blocks.
 
 consider the following:
 
 /* file - main.d **************************************/
 01: template sine(REAL) // where REAL should be one of float,double,real 
 02: {
 03:     float sine(REAL x)
 04:	{
 05:	    asm 
 06:	    {
 07:	        naked		    ; // <- make it naked to get maximum speed
 08:		fld REAL ptr[ESP+4] ; // <- critical opcode
 09:		fsin		    ;
 10:		ret		    ;
 11:	    }
 12:     }
 13: }
 14: alias sine!(float) sine_float; // instantiation
 / *****************************************************/
 An error occurs when typing the last line, due to the instantiation. It says:
 
 main.d(8): end of instruction
 
 I´ve figured out that it comes because of the REAL in the asm block. I also
 tried this for line 08:
 
 08:   fld x
 
 Though this compiles there remains an error at runtime: the program assumes x
to
 be at a different position on the stack and so just a dump of stack memory is
 loaded into the FPU. May this an unfixed bug of the compiler(I´m using dmd)? 
 
 I would be very thankful to everybody who helps me fixing that problem!
 
 


Removing 'naked' and 'ret' instructions fixes the problem.  'real 
ptr[ESP+4]' also didn't work, so use 'fld x' instead.  I think you were 
trying to load the pointer value into the floating point register, which 
doesn't quite work. :)

-- 
Regards,
James Dunne
Mar 25 2006
parent reply manu <manu_member pathlink.com> writes:
James Dunne says...

manu wrote:

 Hi there!
 I´m new to D and quite surprised about all the nice features it provides. So I
 started to write some test apps and also tried to write some templates. It all
 worked perfect until I wanted to use template identifiers in asm blocks.
 
 consider the following:
 
 /* file - main.d **************************************/
 01: template sine(REAL) // where REAL should be one of float,double,real 
 02: {
 03:     float sine(REAL x)
 04:	{
 05:	    asm 
 06:	    {
 07:	        naked		    ; // <- make it naked to get maximum speed
 08:		fld REAL ptr[ESP+4] ; // <- critical opcode
 09:		fsin		    ;
 10:		ret		    ;
 11:	    }
 12:     }
 13: }
 14: alias sine!(float) sine_float; // instantiation
 / *****************************************************/
 An error occurs when typing the last line, due to the instantiation. It says:
 
 main.d(8): end of instruction
 
 I´ve figured out that it comes because of the REAL in the asm block. I also
 tried this for line 08:
 
 08:   fld x
 
 Though this compiles there remains an error at runtime: the program assumes x
to
 be at a different position on the stack and so just a dump of stack memory is
 loaded into the FPU. May this an unfixed bug of the compiler(I´m using dmd)? 
 
 I would be very thankful to everybody who helps me fixing that problem!
 
 


Removing 'naked' and 'ret' instructions fixes the problem.  'real 
ptr[ESP+4]' also didn't work, so use 'fld x' instead.  I think you were 
trying to load the pointer value into the floating point register, which 
doesn't quite work. :)

-- 
Regards,
James Dunne


First thank´s for your help, but 'real ptr[ESP+4]' works, there is no pointer
value
loaded into the FPU. 'REAL ptr[ESP+4]' is the code that doesn´t work(CAPITAL
letters!) 
cause the compiler(dmd) can´t handle template arguments in asm blocks.

And sure using 'fld x' works but only if I don´t use 'naked', as you
said. Otherwise the compiler doesn´t load 'x' from the proper location. Probably

a stack frame is assumed and so it sure fails.

So I think there should be two new features implemented:

1. compiler knows the parameters offsets even if 'naked' is used
2. template arguments can be used inside asm blocks

(Please correct me if one of them is already available.)
Mar 26 2006
parent reply Don Clugston <dac nospam.com.au> writes:
manu wrote:

 James Dunne says...

 manu wrote:

 Hi there!
 I´m new to D and quite surprised about all the nice features it provides. So I
 started to write some test apps and also tried to write some templates. It all
 worked perfect until I wanted to use template identifiers in asm blocks.

 consider the following:

 /* file - main.d **************************************/
 01: template sine(REAL) // where REAL should be one of float,double,real 
 02: {
 03:     float sine(REAL x)
 04:	{
 05:	    asm 
 06:	    {
 07:	        naked		    ; // <- make it naked to get maximum speed
 08:		fld REAL ptr[ESP+4] ; // <- critical opcode
 09:		fsin		    ;
 10:		ret		    ;
 11:	    }
 12:     }
 13: }
 14: alias sine!(float) sine_float; // instantiation
 / *****************************************************/
 An error occurs when typing the last line, due to the instantiation. It says:

 main.d(8): end of instruction

 I´ve figured out that it comes because of the REAL in the asm block. I also
 tried this for line 08:

 08:   fld x

 Though this compiles there remains an error at runtime: the program assumes x
to
 be at a different position on the stack and so just a dump of stack memory is
 loaded into the FPU. May this an unfixed bug of the compiler(I´m using dmd)? 

 I would be very thankful to everybody who helps me fixing that problem!


 Removing 'naked' and 'ret' instructions fixes the problem.  'real 
 ptr[ESP+4]' also didn't work, so use 'fld x' instead.  I think you were 
 trying to load the pointer value into the floating point register, which 
 doesn't quite work. :)

 -- 
 Regards,
 James Dunne


 
 First thank´s for your help, but 'real ptr[ESP+4]' works, there is no pointer
 value
 loaded into the FPU. 'REAL ptr[ESP+4]' is the code that doesn´t work(CAPITAL
 letters!) 
 cause the compiler(dmd) can´t handle template arguments in asm blocks.


Actually REAL is an undocumented reserved word in D assembler! It means 
the same as TBYTE in other assemblers. Use a different name!

Also, I don't think that 'ret' on its own works correctly.

Here's (untemplated) code that works.
real sin(real x)
{
     asm {
         naked;
         fld real ptr [ESP+4];
         fsin;
         ret x.sizeof + x.alignof;
     }
}



 
 And sure using 'fld x' works but only if I don´t use 'naked', as you
 said. Otherwise the compiler doesn´t load 'x' from the proper location.
Probably
 
 a stack frame is assumed and so it sure fails.
 
 So I think there should be two new features implemented:
 
 1. compiler knows the parameters offsets even if 'naked' is used
 2. template arguments can be used inside asm blocks
 
 (Please correct me if one of them is already available.)
Mar 27 2006
parent James Dunne <james.jdunne gmail.com> writes:
Don Clugston wrote:

 manu wrote:
 

 James Dunne says...


 manu wrote:


 Hi there!
 I´m new to D and quite surprised about all the nice features it 
 provides. So I
 started to write some test apps and also tried to write some 
 templates. It all
 worked perfect until I wanted to use template identifiers in asm 
 blocks.

 consider the following:

 /* file - main.d **************************************/
 01: template sine(REAL) // where REAL should be one of 
 float,double,real 02: {
 03:     float sine(REAL x)
 04:    {
 05:        asm 06:        {
 07:            naked            ; // <- make it naked to get maximum 
 speed
 08:        fld REAL ptr[ESP+4] ; // <- critical opcode
 09:        fsin            ;
 10:        ret            ;
 11:        }
 12:     }
 13: }
 14: alias sine!(float) sine_float; // instantiation
 / *****************************************************/
 An error occurs when typing the last line, due to the instantiation. 
 It says:

 main.d(8): end of instruction

 I´ve figured out that it comes because of the REAL in the asm block. 
 I also
 tried this for line 08:

 08:   fld x

 Though this compiles there remains an error at runtime: the program 
 assumes x to
 be at a different position on the stack and so just a dump of stack 
 memory is
 loaded into the FPU. May this an unfixed bug of the compiler(I´m 
 using dmd)?
 I would be very thankful to everybody who helps me fixing that problem!


 Removing 'naked' and 'ret' instructions fixes the problem.  'real 
 ptr[ESP+4]' also didn't work, so use 'fld x' instead.  I think you 
 were trying to load the pointer value into the floating point 
 register, which doesn't quite work. :)

 -- 
 Regards,
 James Dunne



 First thank´s for your help, but 'real ptr[ESP+4]' works, there is no 
 pointer
 value
 loaded into the FPU. 'REAL ptr[ESP+4]' is the code that doesn´t 
 work(CAPITAL
 letters!) cause the compiler(dmd) can´t handle template arguments in 
 asm blocks.


 
 
 Actually REAL is an undocumented reserved word in D assembler! It means 
 the same as TBYTE in other assemblers. Use a different name!
 
 Also, I don't think that 'ret' on its own works correctly.
 
 Here's (untemplated) code that works.
 real sin(real x)
 {
     asm {
         naked;
         fld real ptr [ESP+4];
         fsin;
         ret x.sizeof + x.alignof;
     }
 }
 
 


Yes, I discovered both those oddities when I was playing with the code. 
  I think his point was to make a templated function which took in 
either a float, double, or real, and performed the fsin operation on it, 
returning the value back, obviously.  I just couldn't figure out how the 
ret instruction worked in a naked call.  This sets me right though.

That said, I don't think that templates make sense for use with asm 
blocks; there's too much incompatibility.

-- 
-----BEGIN GEEK CODE BLOCK-----
Version: 3.1
GCS/MU/S d-pu s:+ a-->? C++++$ UL+++ P--- L+++ !E W-- N++ o? K? w--- O 
M--  V? PS PE Y+ PGP- t+ 5 X+ !R tv-->!tv b- DI++(+) D++ G e++>e 
h>--->++ r+++ y+++
------END GEEK CODE BLOCK------

James Dunne
Mar 27 2006