# LLVM C/C++ Compiler User Guide

Contents

- [Introduction](https://docs.qualcomm.com/doc/80-N3040-23/topic/llvm-ccpp-compiler-introduction.html)
    - [Conventions](https://docs.qualcomm.com/doc/80-N3040-23/topic/llvm-ccpp-compiler-introduction.html#conventions)
    - [Technical assistance](https://docs.qualcomm.com/doc/80-N3040-23/topic/llvm-ccpp-compiler-introduction.html#technical-assistance)
- [Functional overview](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html)
    - [Languages](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#languages)
    - [GCC compatibility](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#gcc-compatibility)
    - [Runtime systems](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#runtime-systems)
    - [Processor versions](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#processor-versions)
    - [Processor-specific features](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#processor-specific-features)
    - [C language and compiler references](https://docs.qualcomm.com/doc/80-N3040-23/topic/functional-overview.html#c-language-and-compiler-references)
- [Get started](https://docs.qualcomm.com/doc/80-N3040-23/topic/get-started.html)
    - [Create source file](https://docs.qualcomm.com/doc/80-N3040-23/topic/get-started.html#create-source-file)
    - [Compile program](https://docs.qualcomm.com/doc/80-N3040-23/topic/get-started.html#compile-program)
    - [Execute program](https://docs.qualcomm.com/doc/80-N3040-23/topic/get-started.html#execute-program)
- [Use the compilers](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html)
    - [Start the compilers](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#start-the-compilers)
    - [Input and output files](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#input-and-output-files)
    - [Compiler options](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#compiler-options)
    - [Control diagnostic messages](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#control-diagnostic-messages)
    - [HVX vector operand widths](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#hvx-vector-operand-widths)
    - [HVX and floating-point code generation](https://docs.qualcomm.com/doc/80-N3040-23/topic/use-the-compilers.html#hvx-and-floating-point-code-generation)
- [Code optimization](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html)
    - [Software pipelining](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html#software-pipelining)
    - [Merge functions](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html#merge-functions)
    - [Automatic vectorization](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html#automatic-vectorization)
    - [Link-time optimization](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html#link-time-optimization)
    - [Profile-driven section assignment](https://docs.qualcomm.com/doc/80-N3040-23/topic/code-optimization.html#profile-driven-section-assignment)
- [Compiler security tools](https://docs.qualcomm.com/doc/80-N3040-23/topic/compiler-security-tools.html)
    - [Static analyzer](https://docs.qualcomm.com/doc/80-N3040-23/topic/compiler-security-tools.html#static-analyzer)
    - [Postprocessor](https://docs.qualcomm.com/doc/80-N3040-23/topic/compiler-security-tools.html#postprocessor)
- [Port code from GCC](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html)
    - [Command options](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#command-options)
    - [Errors and warnings](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#errors-and-warnings)
    - [Function declarations](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#function-declarations)
    - [Casting to incompatible types](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#casting-to-incompatible-types)
    - [aligned attribute](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#aligned-attribute)
    - [Reserved registers](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#reserved-registers)
    - [Inline versus extern inline](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#inline-versus-extern-inline)
    - [Lightweight instrumentation](https://docs.qualcomm.com/doc/80-N3040-23/topic/port-code-from-gcc.html#lightweight-instrumentation)
- [Coding practices](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html)
    - [Use int types for loop counters](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#use-int-types-for-loop-counters)
    - [Mark function arguments as restrict (if possible)](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#mark-function-arguments-as-restrict-if-possible)
    - [Do not pass or return structures by value](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#do-not-pass-or-return-structures-by-value)
    - [Avoid control flow in inner-most loops](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#avoid-control-flow-in-inner-most-loops)
    - [Avoid manual loop unrolling](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#avoid-manual-loop-unrolling)
    - [Avoid using inline assembly](https://docs.qualcomm.com/doc/80-N3040-23/topic/coding-practices.html#avoid-using-inline-assembly)
- [Language compatibility](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-compatibility.html)
    - [C compatibility](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-compatibility.html#c-compatibility)
    - [C++ compatibility](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-compatibility.html#hccpp-lang-comp-cpp-comp)
- [Language extensions](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-extensions.html)
    - [Predefined symbols for processor versions](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-extensions.html#predefined-symbols-for-processor-versions)
    - [Predefined symbols for HVX coprocessor versions](https://docs.qualcomm.com/doc/80-N3040-23/topic/language-extensions.html#predefined-symbols-for-hvx-coprocessor-versions)
- [Inline assembly language](https://docs.qualcomm.com/doc/80-N3040-23/topic/inline-assembly-language.html)
    - [ASM statement](https://docs.qualcomm.com/doc/80-N3040-23/topic/inline-assembly-language.html#asm-statement)
    - [Operand constraints](https://docs.qualcomm.com/doc/80-N3040-23/topic/inline-assembly-language.html#operand-constraints)
- [Attributes](https://docs.qualcomm.com/doc/80-N3040-23/topic/attributes.html)
- [Libraries](https://docs.qualcomm.com/doc/80-N3040-23/topic/libraries.html)
    - [C standard library and C++ libraries](https://docs.qualcomm.com/doc/80-N3040-23/topic/libraries.html#c-standard-library-and-c-libraries)
    - [Hexagon-specific libraries](https://docs.qualcomm.com/doc/80-N3040-23/topic/libraries.html#hexagon-specific-libraries)
    - [HVX-specific library](https://docs.qualcomm.com/doc/80-N3040-23/topic/libraries.html#hvx-specific-library)
    - [Hexagon intrinsics emulation library](https://docs.qualcomm.com/doc/80-N3040-23/topic/libraries.html#hexagon-intrinsics-emulation-library)
- [Acknowledgments](https://docs.qualcomm.com/doc/80-N3040-23/topic/llvm-ccpp-acknowledgments.html)
- [References](https://docs.qualcomm.com/doc/80-N3040-23/topic/references.html)

Last Published: Oct 06, 2026

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