[Info-vax] VSI OpenVMS Alpha V8.4-2L1 Layered Product Subset Available

[John Reagan]

On Monday, July 10, 2017 at 4:02:39 PM UTC-4, Stephen Hoffman wrote:
> On 2017-07-10 19:22:38 +0000, John Reagan said:
> 
> > On Monday, July 10, 2017 at 2:09:56 PM UTC-4, clair... at vmssoftware.com wrote:
> >> 
> >> Those
> 
> {..."performance improvements of between 15% and 50%"...}
> 
> >> are real numbers from some tests we ran. Here is my simplistic way to 
> >> look at it. Every execlet is 5%-10% smaller and RMS is 15% smaller, 
> >> compared to unoptimized (the standard build). That means many, many 
> >> code paths in the heart of the operating system are shorter with the 
> >> use of byte/word instructions. You can certainly make a more precise 
> >> analysis but that was from my quick look at comparing the result disks 
> >> from the 2L1 and 2L2 builds, picked a bunch of routines and looked at 
> >> the generated code.
> > 
> > Not to nitpick, but to avoid confusion.  The standard build is NOT 
> > unoptimized.  The build uses the default of /OPT=LEVEL=4 for all 
> > compiles.  However, the default /ARCH value is EV4 (which also sets the 
> > default for /OPT=TUNE).  We added /ARCH=EV6 to the compilations.  We 
> > did not add/remove/change any /OPT qualifiers.
> 
> This approach interspersed duplicated architecture-specific instruction 
> streams throughout the objects and executables, and the compilers added 
> conditional gates to select the appropriate code.

Uh, that isn't what you get.  /ARCH=EV6 gets pure EV6 only code. 

int ext_int;
short ext_word;
char ext_char;

int main() {
  int i;

  i = ext_int;
  i = ext_word;
  i = ext_char;
}

A63D0018     00CC		LDQ	R17, 24(FP)									    ; 000008
A0310000     00D0		LDL	i, EXT_INT				; R1, (R17)
A65D0020     00D4		LDQ	R18, 32(FP)									    ; 000009
30320000     00D8		LDWU	i, EXT_WORD				; R1, (R18)
73E10021     00DC		SEXTW	i, i					; R1, R1
A41D0028     00E0		LDQ	R0, 40(FP)									    ; 000010
28200000     00E4		LDBU	i, EXT_CHAR				; R1, (R0)
73E10001     00E8		SEXTB	i, i					; R1, R1