[PATCH] D150282: [Driver] -ftime-trace: derive trace file names from -o and -dumpdir

[Fangrui Song via Phabricator via cfe-commits]

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Inspired by D133662 <https://reviews.llvm.org/D133662>.
Close https://github.com/llvm/llvm-project/issues/57285

When -ftime-trace is specified and the driver performs both compilation and
linking phases, the trace files are currently placed in the temporary directory
(/tmp by default on *NIX). A more sensible behavior would be to derive the trace
file names from the -o option, similar to how GCC derives auxiliary and dump
file names. Use -dumpdir (D149193 <https://reviews.llvm.org/D149193>) to implement the -gsplit-dwarf like behavior.

The following script demonstrates the time trace filenames.

  #!/bin/sh -e
  PATH=/tmp/Rel/bin:$PATH                # adapt according to your build directory
  mkdir -p d e f
  echo 'int main() {}' > d/a.c
  echo > d/b.c
  
  a() { rm $1 || exit 1; }
  
  clang -ftime-trace d/a.c d/b.c         # previously /tmp/[ab]-*.json
  a a-a.json; a a-b.json
  clang -ftime-trace d/a.c d/b.c -o e/x  # previously /tmp/[ab]-*.json
  a e/x-a.json; a e/x-b.json
  clang -ftime-trace d/a.c d/b.c -o e/x -dumpdir f/
  a f/a.json; a f/b.json
  clang -ftime-trace=f d/a.c d/b.c -o e/x
  a f/a-*.json; a f/b-*.json
  
  clang -c -ftime-trace d/a.c d/b.c
  a a.json b.json
  clang -c -ftime-trace=f d/a.c d/b.c
  a f/a.json f/b.json
  
  clang -c -ftime-trace d/a.c -o e/xa.o
  a e/xa.json
  clang -c -ftime-trace d/a.c -o e/xa.o -dumpdir f/
  a f/a.json

The driver checks `-ftime-trace` and `-ftime-trace=`, infers the trace file
name, and passes `-ftime-trace=` to cc1. The `-ftime-trace` cc1 option is
removed.

This patch doesn't attempt to change offloading behavior (D133662 <https://reviews.llvm.org/D133662>).


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D150282

Files:
  clang/include/clang/Driver/Compilation.h
  clang/include/clang/Driver/Options.td
  clang/include/clang/Frontend/FrontendOptions.h
  clang/lib/Driver/Driver.cpp
  clang/lib/Driver/ToolChains/Clang.cpp
  clang/test/Driver/ftime-trace.cpp
  clang/tools/driver/cc1_main.cpp

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