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Floating point issue?

I have found in my code where register R8 is being used as a loop variable in a FOR loop. In the loop, a call is made to a floating point library routine (fpcmp.s), which inadvertently destroys R8. This makes my FOR loop an infinite loop. Could this somehow be a setup issue? Has anyone else seen similar problems?

Parents

0 Dave Burbick over 20 years ago in reply to Bradford Al

I am using a target system. Code from list file is below. Problem occurs at Line 454. First Line of FPCMP destroys R8.

 00000418            ; SCOPE-START
 1376:                      for (k=0, ksav = 0;k < 5; k++)
 00000418          L_238:
 00000418  E3A08000  MOV         R8,#0x0
 0000041C  ---- Variable 'k' assigned to Register 'R8' ----
 0000041C  E3A03000  MOV         R3,#0x0
 00000420  ---- Variable 'ksav' assigned to Register 'R3' ----
 00000420  EA000010  B           L_236  ; Targ=0x468
 00000424          L_237:
 1378:                             if (vec0[k] < vec0[ksav])
 00000424  E1A00003  MOV         R0,R3 ; ksav
 00000428  E1A01C00  MOV         R1,R0,LSL #24 ; ksav
 0000042C  E1A01C21  MOV         R1,R1,LSR #24
 00000430  E1A01101  MOV         R1,R1,LSL #2
 00000434  E28D0008  ADD         R0,R13,#0x0008
 00000438  E7904001  LDR         R4,[R0,+R1]
 0000043C  E1A01008  MOV         R1,R8 ; k
 00000440  E1A01C01  MOV         R1,R1,LSL #24 ; k
 00000444  E1A01C21  MOV         R1,R1,LSR #24
 00000448  E1A01101  MOV         R1,R1,LSL #2
 0000044C  E7900001  LDR         R0,[R0,+R1]
 00000450  E1A01004  MOV         R1,R4
 00000454  EBFFFEE9  BL          ?C?FPCMP?A  ; Targ=0x0 ; ?C?FPCMP?A
 00000458  2A000000  BCS         L_234  ; Targ=0x460
 1380:                                    ksav = k;
 0000045C  E1A03008  MOV         R3,R8 ; k
 1382:                      }
 00000460          L_234:
 00000460  E2888001  ADD         R8,R8,#0x0001 ; k
 00000464  E20880FF  AND         R8,R8,#0x00FF
 00000468          L_236:
 00000468  E1A00008  MOV         R0,R8 ; k
 0000046C  E1A00C00  MOV         R0,R0,LSL #24 ; k
 00000470  E1A00C20  MOV         R0,R0,LSR #24
 00000474  E3500005  CMP         R0,#0x0005
 00000478  BAFFFFE9  BLT         L_237  ; Targ=0x424
 1383:                      if (j == 2)
 0000047C  E1A00002  MOV         R0,R2 ; j
 00000480  E1A00C00  MOV         R0,R0,LSL #24 ; j
 00000484  E1A00C20  MOV         R0,R0,LSR #24
 00000488  E3500002  CMP         R0,#0x0002
 0000048C  1A000005  BNE         L_240  ; Targ=0x4A8
 1384:                             min = vec0[ksav];    // saves third smallest element in min variable
 00000490  E1A00003  MOV         R0,R3 ; ksav
 00000494  E1A01C00  MOV         R1,R0,LSL #24 ; ksav
 00000498  E1A01C21  MOV         R1,R1,LSR #24
 0000049C  E1A01101  MOV         R1,R1,LSL #2
 000004A0  E28D0008  ADD         R0,R13,#0x0008
 000004A4  E7906001  LDR         R6,[R0,+R1]
 000004A8          L_240:
 1386:                      vec0[ksav]= 1.0e05;
 000004A8  E5100000  LDR         R0,=0x47C35000
 000004AC  E1A01003  MOV         R1,R3 ; ksav
 000004B0  E1A03C01  MOV         R3,R1,LSL #24 ; ksav
 000004B4  E1A03C23  MOV         R3,R3,LSR #24
 000004B8  E1A03103  MOV         R3,R3,LSL #2
 000004BC  E28D1008  ADD         R1,R13,#0x0008
 000004C0  E7810003  STR         R0,[R1,+R3]
 000004C4            ; SCOPE-END

Reply

0 Dave Burbick over 20 years ago in reply to Bradford Al

I am using a target system. Code from list file is below. Problem occurs at Line 454. First Line of FPCMP destroys R8.

 00000418            ; SCOPE-START
 1376:                      for (k=0, ksav = 0;k < 5; k++)
 00000418          L_238:
 00000418  E3A08000  MOV         R8,#0x0
 0000041C  ---- Variable 'k' assigned to Register 'R8' ----
 0000041C  E3A03000  MOV         R3,#0x0
 00000420  ---- Variable 'ksav' assigned to Register 'R3' ----
 00000420  EA000010  B           L_236  ; Targ=0x468
 00000424          L_237:
 1378:                             if (vec0[k] < vec0[ksav])
 00000424  E1A00003  MOV         R0,R3 ; ksav
 00000428  E1A01C00  MOV         R1,R0,LSL #24 ; ksav
 0000042C  E1A01C21  MOV         R1,R1,LSR #24
 00000430  E1A01101  MOV         R1,R1,LSL #2
 00000434  E28D0008  ADD         R0,R13,#0x0008
 00000438  E7904001  LDR         R4,[R0,+R1]
 0000043C  E1A01008  MOV         R1,R8 ; k
 00000440  E1A01C01  MOV         R1,R1,LSL #24 ; k
 00000444  E1A01C21  MOV         R1,R1,LSR #24
 00000448  E1A01101  MOV         R1,R1,LSL #2
 0000044C  E7900001  LDR         R0,[R0,+R1]
 00000450  E1A01004  MOV         R1,R4
 00000454  EBFFFEE9  BL          ?C?FPCMP?A  ; Targ=0x0 ; ?C?FPCMP?A
 00000458  2A000000  BCS         L_234  ; Targ=0x460
 1380:                                    ksav = k;
 0000045C  E1A03008  MOV         R3,R8 ; k
 1382:                      }
 00000460          L_234:
 00000460  E2888001  ADD         R8,R8,#0x0001 ; k
 00000464  E20880FF  AND         R8,R8,#0x00FF
 00000468          L_236:
 00000468  E1A00008  MOV         R0,R8 ; k
 0000046C  E1A00C00  MOV         R0,R0,LSL #24 ; k
 00000470  E1A00C20  MOV         R0,R0,LSR #24
 00000474  E3500005  CMP         R0,#0x0005
 00000478  BAFFFFE9  BLT         L_237  ; Targ=0x424
 1383:                      if (j == 2)
 0000047C  E1A00002  MOV         R0,R2 ; j
 00000480  E1A00C00  MOV         R0,R0,LSL #24 ; j
 00000484  E1A00C20  MOV         R0,R0,LSR #24
 00000488  E3500002  CMP         R0,#0x0002
 0000048C  1A000005  BNE         L_240  ; Targ=0x4A8
 1384:                             min = vec0[ksav];    // saves third smallest element in min variable
 00000490  E1A00003  MOV         R0,R3 ; ksav
 00000494  E1A01C00  MOV         R1,R0,LSL #24 ; ksav
 00000498  E1A01C21  MOV         R1,R1,LSR #24
 0000049C  E1A01101  MOV         R1,R1,LSL #2
 000004A0  E28D0008  ADD         R0,R13,#0x0008
 000004A4  E7906001  LDR         R6,[R0,+R1]
 000004A8          L_240:
 1386:                      vec0[ksav]= 1.0e05;
 000004A8  E5100000  LDR         R0,=0x47C35000
 000004AC  E1A01003  MOV         R1,R3 ; ksav
 000004B0  E1A03C01  MOV         R3,R1,LSL #24 ; ksav
 000004B4  E1A03C23  MOV         R3,R3,LSR #24
 000004B8  E1A03103  MOV         R3,R3,LSL #2
 000004BC  E28D1008  ADD         R1,R13,#0x0008
 000004C0  E7810003  STR         R0,[R1,+R3]
 000004C4            ; SCOPE-END

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