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  1. Embedded Software & Tools
  2. EXT_EP-10084

tiarmclang: optimizer removes empty loops that don't have side effects

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    • Icon: Bug Bug
    • Resolution: Fixed
    • Icon: Medium Medium
    • Code Generation Tools
    • CODEGEN-6288
    • ARMCLANG_1.1.0.STS
    • ARMCLANG_2.1.0.LTS
    • default
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      An _asm(" "); statement can be inserted into the body of an empty loop to mark the loop as having a side effect so that the optimizer will not removes it

      while (1) {
        _asm(" ");
      }
      Show
      An _asm(" "); statement can be inserted into the body of an empty loop to mark the loop as having a side effect so that the optimizer will not removes it while (1) {   _asm(" "); }

      When the following C code is compiled:

       

      void xdc_runtime_Startup_reset__I(void)
{
    ti_sysbios_rom_cortexm_cc26xx_cc26x2v2_CC26xx_checkRevision__E();
}

void ti_sysbios_rom_cortexm_cc26xx_cc26x2v2_CC26xx_checkRevision__E()
{
    if (*((UInt32 *)(268612608)) != 286529877) {
        ti_sysbios_rom_cortexm_cc26xx_cc26x2v2_CC26xx_badRomRevision__E();
    }
}

void ti_sysbios_rom_cortexm_cc26xx_cc26x2v2_CC26xx_badRomRevision__E() {
    /* Loop here forever if application is built with wrong version of ROM image */
    while(1) {
        ;
    }
}
 

      The generated code for xdc_runtime_Startup_reset__I() becomes the following empty function:

      xdc_runtime_Startup_reset__I()
     000008fa: 4770 bx lr

            syncuser TI User
            syncuser TI User
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              Created:
              Updated:
              Resolved: