[utils] Add utils/update_cc_test_checks.py

[utils] Add utils/update_cc_test_checks.py

A utility to update LLVM IR in C/C++ FileCheck test files.

Example RUN lines in .c/.cc test files:

// RUN: %clang -S -Os -DXX %s -o - | FileCheck %s
// RUN: %clangxx -S -Os %s -o - | FileCheck -check-prefix=IR %s

Usage:

% utils/update_cc_test_checks.py --llvm-bin=release/bin test/a.cc
% utils/update_cc_test_checks.py --c-index-test=release/bin/c-index-test --clang=release/bin/clang /tmp/c/a.cc

    // NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
    // RUN: %clang -emit-llvm -S -Os -DXX %s -o - | FileCheck -check-prefix=AA %s
    // RUN: %clangxx -emit-llvm -S -Os %s -o - | FileCheck -check-prefix=BB %s
    using T =
    #ifdef XX
        int __attribute__((vector_size(16)))
    #else
        short __attribute__((vector_size(16)))
    #endif
        ;

    // AA-LABEL: _Z3fooDv4_i:
    // AA:       entry:
    // AA-NEXT:    %add = shl <4 x i32> %a, <i32 1, i32 1, i32 1, i32 1>
    // AA-NEXT:    ret <4 x i32> %add
    //
    // BB-LABEL: _Z3fooDv8_s:
    // BB:       entry:
    // BB-NEXT:    %add = shl <8 x i16> %a, <i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
    // BB-NEXT:    ret <8 x i16> %add
    T foo(T a) {
      return a + a;
    }

Differential Revision: https://reviews.llvm.org/D42712

llvm-svn: 326591