9.6. TI ARM CLANG Usage and Migration Guidelines¶

9.6.1.1. Introduction to TI ARM CLANG¶

The tiarmclang compiler is based on the open source LLVM compiler infrastructure and its Clang front-end. tiarmclang uses the TI Linker and C runtime for stability and reduced code size.

Benefits of tiarmclang include:

• Excellent C/C++ standards support
• Source-based code coverage
• Support for migration from armcl
• Improved code size over armcl/gcc
• Ease of use with fast compiles and expressive diagnostic messages
• GCC compatibility
• Comprehensive documentation: Getting Started Guide, Migration Guide and Compiler Tools User Manual
• Compiler Qualification Kit to assist qualifying the compiler to functional safety standards such as ISO 26262 and IEC 61508.

As a part of this migration activity, we are moving away from ‘armcl’ compiler tool chain and will be using ‘tiarmclang’ going forward. This will need some changes in CSL-FL, Drives, Sample Application and Linker Command File. The intent of this page is look at all the changes needed.

9.6.3.1. Build Changes¶

9.6.3.2. Source File/Code Changes¶

Here are few and quick changes needed (following list mostly contains armcl options with corresponding counterparts in tiarmclang, this should be mostly ‘find and replace’ in the source code):

9.6.4.1. Structure Initialization¶

• Failing to initialize the structure instance may cause unexpected application failures

• Clang tool-chain does not allow initializing only a few members of structure (and rest being set to 0) using below method:

  struct DemoStruct_t
  {
      uint32_t memberA;
      /**< Member A */
      uint32_t memberB;
      /**< Member B */
      uint32_t memberC;
      /**< Member C */
  };
  
  /* Initializing Member A of the structure */
  DemoStruct_t demoStructInst = {22U};
  

• User can either initialize all members of the structure by enclosing them into pair of curly parenthesis (“{ }”) OR initialize particular member of structure like ”.<member_name>=<initialization_value>;” Here are few examples to do the same:

  • Example 1:

  struct DemoStruct_t
  {
      uint32_t memberA;
      /**< Member A */
      uint32_t memberB;
      /**< Member B */
      uint32_t memberC;
      /**< Member C */
  };
  
  DemoStruct_t demoStructInst[2] =
  {
      /* Initialize all 3 members of the structure */
      {
          .memberA = 22U;
          .memberB = 44U;
          .memberC = 88U;
      },
      /* Initialize only needed 2 members of the structure */
      {
          .memberA = 22U;
          .memberC = 88U;
      },
  };
  

  • Example 2:

  struct DemoStruct_t
  {
      uint32_t memberA;
      /**< Member A */
      uint32_t memberB;
      /**< Member B */
      uint32_t memberC;
      /**< Member C */
  };
  
  /* This will initialize all members to '0' */
  DemoStruct_t demoStructInst = {0U};
  
  demoStructInst.memberA = 22U;
  

9.6.4.2. Linker Command File Changes¶

• Add `’.rodata’` section in the linker command file and assign/allot it to same section as ‘.const’ sections.

9.6.4.3. Other Key Care Abouts¶

• For armcl Intrinsics, the ‘arm_acle.h’ Header file needs to be included
• Non-ACLE armcl Compiler Intrinsics are not supported in tiarmclang
• Accessing armcl Compiler Intrinsics via the ‘ti_compatibility.h’ Header File