Practical WebAssembly/

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LLVM in Action

LLVM in Action

Learn how LLVM generates machine code for different architectures from a high-level language.

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In this section, let’s use LLVM’s Clang compiler to compile native code into LLVM IR. This will give a better idea of how LLVM works and will be useful for understanding how the compilers use LLVM later.

We first create a C file called sum.c with the following command:

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touch sum.c

Then we add the following code to it:

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unsigned sum(unsigned a, unsigned b) {
  return a + b;
}

The sum.c file contains a simple sum function that takes in two unsigned integers and returns the sum of them. LLVM provides the Clang LLVM compiler to compile the C source code. In order to generate the LLVM IR, run the following command:

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clang -S -O3 -emit-llvm sum.c

We provided the Clang compiler with the -S, ...