Norcroft ARM C 1.50A Aug  7 1987


                |v$codeseg|
000000  ea000000  B       |__main|
/*
!
! The hand-generated code below should be producable by PSR's compiler if it:
! A) delays stores as late as possible
!
! B) remembers registers over procedure calls
!
! C) has a general algorithm for drop-through conditionally executed
!    instructions, i.e. if there are no instructions between a conditional 
!    branch and its destination which set the condition codes, and the
!    sequence is less that a certain length, then all the instructions
!    within the sequence can be made conditional.
!
! D) does as above, but also allows instructions within the sequence
!    whose subsequent execution depends on the same condition, e.g.
!
!    %if a=b %and c=d %then a=b
!
!    CmpS   R0,R1            NAIVE STYLE
!    Bne    elsepart
!    Cmps   R2,R3
!    Bne    elsepart
!    Mov    R0,R2
!
!    CmpS   R0,R1            RULE (C) ABOVE
!    Bne    elsepart
!    CmpS   R2,R3
!    MovEQ  R0,R2
!
!    CmpS   R0,R1            RULE (D) SPECIAL CASE
!    CmpSEQ R2,R3
!    MovEQ  R0,R2
!
! E) alters conditions to generate similar condition codes on
!    condition AND condition AND condition to generate more cases
!    to which rule (D) can be applied.
!
! F) adjusts constants in < or <= cases to favour above, i.e. turning
!    CMP R,#const & BLE ... into CMP R,#const-1 & BLT ... etc.
!
! G) changes Newline back from the current implicit printsymbol(10) -
!    there is no run-time overhead in moving the MOV R0,#10 over to
!    the procedure body instead of having it in every call where it
!    takes up space - after all, Peter's code-moving stuff ought to
!    get %permroutine newline;printsymbol(10);%end correct - it will
!    place the Mov R0,#10 before the body of %permroutine printsymbol
!    and generate a suitable entry point for it...
!       Personally, I would recommend stacking/restoring R0 as well
!    as it might keep another variable in a register for a bit longer...
!
! I've only suggested optimisations which fit into the style of PSR's
! compilers...
!
*/
extern int readnum(void);
extern void write(int num, int pl);
extern void newline(void);

void main(void) {
000004  6e69616d  DCB     &6d,&61,&69,&6e         ; 'main'
000008  00000000  DCB     &00,&00,&00,&00         ; '\0\0\0\0'
00000c  ff000008  DCD     &ff000008
                main
<stdin>, line 59, Warning: extern 'main' needs to be 'int' function
int a,i,b;
000010  e1a0b00c  MOV     ip, sp
000014  e92cccf0  STMFD   sp!, {v1,v2,v3,v4,fp,ip,lk,pc}
000018  e24ba004  SUB     fp, ip, #4              ; 00000004
00001c  e15c000d  CMPS    sp, sl
000020  3b000000  BLCC    |x$stack_overflow|

  a = readnum();
000024  e3a04000  MOV     v1, #0                  ; 00000000
000028  eb000000  BL      readnum
  i = readnum();
00002c  e1a07000  MOV     v4, a1
000030  eb000000  BL      readnum
  b = readnum();
000034  e1a05000  MOV     v2, a1
000038  eb000000  BL      readnum
00003c  e1a06000  MOV     v3, a1

  if ((a <= i) && (i <= b)) {
000040  e1570005  CMPS    v4, v2
000044  ca000001  BGT     main+&40                ; 00000001
000048  e1550006  CMPS    v2, v3
    i = 22;
00004c  d3a05016  MOVLE   v2, #22                 ; 00000016
  };

  if ((22 <= i) && (i <= b)) {
000050  e3550016  CMPS    v2, #22                 ; 00000016
000054  ba000001  BLT     main+&50                ; 00000001
000058  e1550006  CMPS    v2, v3
    i = 44;
00005c  d3a0502c  MOVLE   v2, #44                 ; 0000002C
  };

  if ((a <= i) && (i <= 77)) {
000060  e1570005  CMPS    v4, v2
000064  ca000001  BGT     main+&60                ; 00000001
000068  e355004d  CMPS    v2, #77                 ; 0000004D
    i = 99;
00006c  d3a05063  MOVLE   v2, #99                 ; 00000063
  };

  if ((11 <= i) && (i <= 100)) {
000070  e355000b  CMPS    v2, #11                 ; 0000000B
000074  ba000001  BLT     main+&70                ; 00000001
000078  e3550064  CMPS    v2, #100                ; 00000064
    i = 1;
00007c  d3a05001  MOVLE   v2, #1                  ; 00000001
  };

  write(a,0);
000080  e1a00007  MOV     a1, v4
000084  e1a01004  MOV     a2, v1
000088  eb000000  BL      write
  newline();
00008c  eb000000  BL      newline
  write(i,0);
000090  e1a00005  MOV     a1, v2
000094  e1a01004  MOV     a2, v1
000098  eb000000  BL      write
  newline();
00009c  eb000000  BL      newline
  write(b,0);
0000a0  e1a00006  MOV     a1, v3
0000a4  e1a01004  MOV     a2, v1
0000a8  eb000000  BL      write
0000ac  e91a54f0  LDMEA   fp, {v1,v2,v3,v4,fp,sp,lk}
  newline();
0000b0  ea000000  B       newline

};
<stdin>, line 89, Error: declaration with no effect

 AREA |C$$data|
|v$dataseg|

 EXPORT main

 IMPORT newline
 IMPORT write
 IMPORT readnum
 IMPORT |x$stack_overflow|
 IMPORT |__main|

 END
<stdin>: 1 warning, 1 error, 0 serious errors.