PK40952: GENERATING BAD CODE FOR CALL TO C LIBRARY FUNCTION

APAR status

• Closed as program error.

Error description

• Product: Apex Ada
  
  Platform: Alpha
  
  Version: 4.2.2b plus patches
  
  Installed configuration is listed at the end of this file.
  
  
  
  Description:
  
  Generating bad code for call to C library function:
  
  
  
  The attached Timed_Io package is not working due to CG errors wi
  th
  4.2.2b.  The call to Select has bad parameters formed.
  
  OPTIMIZATION_LEVEL is 0.
  
  
  
  The code generated from 4.2.2b for the Select call is:
  
  
  
   Ret_Val := Selectio (Interfaces.Integer_32 (Fd + 1),
  
          Fd_Set'Unchecked_Access, null, null, Time_Out);
  
  
  
   -- Check returned status
  
  addl/v      s1, 01, a0          ;a0 := s1 + 1
  
  ldl         a4, -020(s4)        ;a4 := SEXT((s4 - 32))
  
  ldl         a5, -01c(s4)        ;a5 := SEXT((s4 - 28))
  
  bis         zero, zero, a2      ;a2 := zero
  
  bis         zero, zero, a3      ;a3 := zero
  
  ldq         t12, 07da0(gp)      ;t12 := (gp + 32160)
  
  trapb                           ;trap barrier
  
  jsr         ra, (t12), 0a9c4    ;-? __select
  
  ldah        gp, 01ffb(ra)       ;gp := ra + 536543232
  
  lda         gp, -064bc(gp)      ;gp := gp - 25788
  
  bis         zero, v0, t8        ;t8 := v0
  
   if Ret_Val = -1 then
  
  
  
  The code generated for 4.0.0b is:
  
  
  
   Ret_Val := Selectio (Interfaces.Integer_32 (Fd + 1),
  
  addl/v      s1, 01, a0          a0 := s1 + 1
  
  lda         a1, -018(s4)        a1 := s4 - 24
  
  lda         a4, -020(s4)        a4 := s4 - 32
  
  bis         zero, zero, a2      a2 := zero
  
  bis         zero, zero, a3      a3 := zero
  
  ldq         t12, 07ab8(gp)      t12 := (gp + 31416)
  
  trapb                           trap barrier
  
  jsr         ra, (t12), 06654    -? __select
  
  ldah        gp, 01fee(ra)       gp := ra + 535691264
  
  lda         gp, 07bd4(gp)       gp := gp + 31700
  
  bis         zero, v0, t0        t0 := v0
  
   if Ret_Val = -1 then
  
  
  
  You can see that the a1 register is not being set properly in th
  e 4.2.2b
  code (which is the recv fd set parameter).
  
  
  
  This causes a bad call to select and our application fails.
  

Local fix

Problem summary

• Ada compiler incorrectly passing parameter by value
  rather than
  by reference.
  

Problem conclusion

• For a subprogram with a
  non-Ada convention , the Ada
  compiler will not alter parameter
  passing conventions.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  ADA DEV EE UNIX

• Fixed component ID

  5724G1501

Applicable component levels

• R42L PSN

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