[all-commits] [llvm/llvm-project] 0df26b: [CMake] Enable ccache depend mode when PCH is enab...

[Alexis Engelke via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 0df26b857065991b50725ca85f7a8728c60ceea9
      https://github.com/llvm/llvm-project/commit/0df26b857065991b50725ca85f7a8728c60ceea9
  Author: Alexis Engelke <engelke at in.tum.de>
  Date:   2026-09-22 (Tue, 22 Sep 2026)

  Changed paths:
    M llvm/CMakeLists.txt
    M llvm/cmake/modules/HandleLLVMOptions.cmake

  Log Message:
  -----------
  [CMake] Enable ccache depend mode when PCH is enabled (#225118)

ccache with PCH sometimes falls back to the preprocessor mode even when
using Clang. Enable ccache's "depend mode" to only rely on dependencies
as emitted by the compiler when PCH is enabled.

This requires moving the ccache logic to HandleLLVMOptions.cmake, as
whether PCH is enabled now impacts the ccache options. While moving,
also deduplicate the ccache+Clang detection logic and bundle all
PCH-related configurations together.

To ease debugging the ccache configuration, print the ccache command and
options as cmake output.

Fixes https://github.com/llvm/llvm-project/issues/225047.

See: https://github.com/ccache/ccache/issues/1686



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