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Groups > alt.os.development > #8750

Re: Smaller C

From "Benjamin David Lunt" <zfysz@fysnet.net>
Newsgroups alt.os.development
Subject Re: Smaller C
Date 2015-09-11 21:37 -0700
Organization Aioe.org NNTP Server
Message-ID <mt0a72$7kj$1@speranza.aioe.org> (permalink)
References (14 earlier) <77032cbf-7538-42ef-a1ad-73f3ca6ee38d@googlegroups.com> <13fd448e-f885-4785-9368-04c0b75e543c@googlegroups.com> <863a5219-999a-4028-b567-a8e1e282af5d@googlegroups.com> <79c0cfce-38ec-4bcc-bd5f-a25808ffb8ea@googlegroups.com> <39da71f8-7e21-4fcb-84da-263d5c81059f@googlegroups.com>

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"Alexei A. Frounze" <alexfrunews@gmail.com> wrote in message 
news:39da71f8-7e21-4fcb-84da-263d5c81059f@googlegroups.com...
> One more improvement for Ben's 50+K executable. :)
> Actually, I've had a couple of requests for this.
>
> Anyway, the prologue/epilogue parts are now shorter.
>
> This is what Smaller C used to generate:
> _foo:
>  push bp
>  mov  bp, sp
>  jmp  L1
> L2:
>  ...
>  leave
>  ret
> L1:
>  sub  sp, size_of_locals
>  jmp  L2
>
> This is what it generates now:
> _foo:
>  push bp
>  mov  bp, sp
>  sub  sp, size_of_locals
>  ...
>  leave
>  ret
>
> If there are no locals, there's no sub either. This shaves ~500 bytes
> off a 64KB 16-bit code section.
>
> The trick? fgetpos()/fsetpos() majic.
> The price? Must always supply the output assembly file name to smlrc.

Alex,

I hope you don't mind, may I make a small suggestion for your above
code?

@@ -6965,7 +6965,7 @@
 #endif
 #endif
         GenFxnProlog();
-        CurFxnEpilogLabel = LabelCnt++;
+        CurFxnEpilogLabel = 0;

         AddFxnParamSymbols(lastSyntaxPtr);

@@ -6997,7 +6997,9 @@
           GenExpr();
         }

-        GenNumLabel(CurFxnEpilogLabel);
+        // only need to include the label if we used it
+        if (CurFxnEpilogLabel > 0)
+          GenNumLabel(CurFxnEpilogLabel);

 #ifndef MIPS
 #ifdef CAN_COMPILE_32BIT
@@ -7460,7 +7462,7 @@
       // If this return is the last statement in the function, the epilogue 
immediately
       // follows and there's no need to jump to it.
       if (!(tok == '}' && ParseLevel == 1 && !Main))
-        GenJumpUncond(CurFxnEpilogLabel);
+        GenJumpUncond(CurFxnEpilogLabel = LabelCnt++);
     }
     else if (tok == tokWhile)
     {

Currently, whether the label is needed or not, your/my code supplies
the ending label 'CurFxnEpilogLabel'.  No big deal, the output assembles
just fine.  However, one less label to see/process/store/etc., if
you make the above change.

Hope you don't mind me sending you a diff and a suggestion.

Please let me know if the above change will break anything though.

Thanks,
Ben

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Thread

Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-11 20:39 -0700
  Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-12 04:24 -0400
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-12 03:17 -0700
      Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-13 03:28 -0400
    Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-12 19:12 +0100
      Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-07-12 17:09 -0700
      Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-13 11:10 +0100
        Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-13 23:13 -0400
          Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-07-14 09:08 +0100
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-07-15 02:23 -0400
  Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-08-15 02:12 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-06 15:54 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-07 12:19 -0700
        Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-07 13:30 -0700
          Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 19:38 -0700
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 19:49 -0700
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-09 20:58 -0700
            Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-10 01:45 -0700
              Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-10 10:45 -0700
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-10 23:20 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-11 09:26 +0200
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-11 09:50 +0200
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-11 00:58 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 17:38 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-11 23:39 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 19:39 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-12 11:22 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:21 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-12 21:53 +0200
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:37 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 09:49 +0100
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 12:58 +0200
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 07:32 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:05 +0100
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-14 13:19 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-15 00:01 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-18 14:48 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-26 16:23 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2015-09-27 00:23 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-26 16:37 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:17 -0400
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:24 -0400
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:46 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-16 16:14 +0000
                Re: Smaller C Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-23 13:20 -0500
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-27 13:52 +0000
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-27 10:28 -0400
                Re: Smaller C James Harris <james.harris.1@gmail.com> - 2016-01-16 16:31 +0000
                Re: Smaller C Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-23 13:20 -0500
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-18 16:21 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-20 17:25 -0700
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 12:43 +0200
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 09:21 +0100
                Re: Smaller C "wolfgang kern" <nowhere@never.at> - 2015-09-13 13:02 +0200
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:09 +0100
                Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 13:32 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 18:51 -0400
                Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 18:16 -0700
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:36 -0700
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-12 11:56 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:45 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 10:28 +0100
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 02:53 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:17 -0400
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 16:54 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 21:39 -0400
                Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 20:31 -0700
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 09:03 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-13 19:48 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 21:33 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-14 23:17 +0100
                Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-20 17:37 -0400
                Re: Smaller C "James Harris" <james.harris.1@gmail.com> - 2015-09-20 23:46 +0100
  Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 21:37 -0700
    Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-11 22:29 -0700
      Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 03:25 -0700
        Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 11:18 -0700
          Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 11:39 -0700
          Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 03:47 -0400
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:31 -0400
          Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-13 02:00 -0700
            Re: Smaller C "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-13 11:31 -0400
            Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-13 09:15 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-12 02:45 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-12 10:55 -0700
  Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-15 19:23 -0700
    Re: Smaller C "Alexei A. Frounze" <alexfrunews@gmail.com> - 2015-09-16 03:03 -0700
      Re: Smaller C "Benjamin David Lunt" <zfysz@fysnet.net> - 2015-09-16 10:17 -0700

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