github.com/distbuild/reclient@v0.0.0-20240401075343-3de72e395564/internal/pkg/inputprocessor/action/nacl/preprocessor.go (about)

     1  // Copyright 2023 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  // Package nacl performs include processing given a valid nacl action.
    16  package nacl
    17  
    18  import (
    19  	"fmt"
    20  	"path/filepath"
    21  	"strings"
    22  
    23  	"github.com/bazelbuild/reclient/internal/pkg/inputprocessor/action/cppcompile"
    24  	"github.com/bazelbuild/reclient/internal/pkg/inputprocessor/flags"
    25  )
    26  
    27  // Preprocessor is the preprocessor of nacl compile actions.
    28  type Preprocessor struct {
    29  	*cppcompile.Preprocessor
    30  }
    31  
    32  // ComputeSpec computes cpp header dependencies.
    33  // As the versions of nacl that we work with are quite defased from our llvm
    34  // version, we have to tweak the flags before treating them as a regular clang
    35  // action.
    36  func (p *Preprocessor) ComputeSpec() error {
    37  	var hasTarget bool
    38  	finalFlags := []*flags.Flag{}
    39  	for _, flag := range p.Flags.Flags {
    40  		if strings.HasPrefix(flag.Key, "-pnacl") || strings.HasPrefix(flag.Key, "--pnacl") || (flag.Key == "--" && strings.HasPrefix(flag.Value, "pnacl")) {
    41  			// Chrome pnacl uses a custom clang compiler, pnacl-clang,
    42  			// which supports flags that ClangScanDeps would never
    43  			// support.
    44  			continue
    45  		}
    46  		if flag.Key == "-target" || flag.Key == "--target=" {
    47  			// See if !hasTarget below for more context.
    48  			hasTarget = true
    49  		}
    50  		finalFlags = append(finalFlags, flag)
    51  	}
    52  
    53  	binaryName := filepath.Base(p.Flags.ExecutablePath)
    54  	containsNacl := strings.Contains(binaryName, "nacl")
    55  	if !containsNacl {
    56  		return fmt.Errorf("nacl binary doesn't include 'nacl' in basename: %v", p.Flags.ExecutablePath)
    57  	}
    58  
    59  	if !hasTarget && containsNacl {
    60  		// Nacl compilers target a specific architecture that's potentially different
    61  		// than the host machine's architecutre, eg x86_64, i686 or mipsel. Those flavors have their
    62  		// own defined macros, included headers and libraries. Our implementation of clang scan deps
    63  		// sometimes is unable to find out that we're attempting a cross-compilation of sorts,
    64  		// so we add a `--target` flag as a cheat for scan deps.
    65  		//
    66  		// In Chrome, NaCl binaries all follow the naming
    67  		// {arch}-nacl-{tool}, eg x86_64-nacl-clang, mipsel-nacl-ld.
    68  		// The exception being for pnacl, where the binaries are named pnacl-{tool}.
    69  		// Under the hood, pnacl-clang uses the i686-nacl-clang.
    70  		arch := strings.Split(binaryName, "nacl")
    71  		if arch[0] != "p" {
    72  			finalFlags = append(finalFlags, &flags.Flag{Key: "--target=", Value: fmt.Sprintf("%snacl", arch[0]), Joined: true})
    73  		} else {
    74  			// Under the hood, pnacl-clang is a python script that runs i686-nacl-clang.
    75  			finalFlags = append(finalFlags, &flags.Flag{Key: "--target=", Value: "i686-nacl", Joined: true})
    76  		}
    77  	}
    78  
    79  	p.Flags.Flags = finalFlags
    80  	return p.Preprocessor.ComputeSpec()
    81  }