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Merge pull request #51 from woodruffw-forks/ww/llvm-link-env-flags

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Support LLVM_LINK_FLAGS
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Ian A Mason 2021-06-29 11:12:37 -07:00 committed by GitHub
commit b0c77e1ac2
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3 changed files with 21 additions and 0 deletions
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6
README.md
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@ -29,6 +29,7 @@ bitcode in parallel, and is faster. A comparison between the two tools can be gl
| LLVM_COMPILER | *not supported* (clang only)|
| LLVM_GCC_PREFIX | *not supported* (clang only)|
| LLVM_DRAGONEGG_PLUGIN | *not supported* (clang only)|
| LLVM_LINK_FLAGS | *not supported* |
This project, `gllvm`, provides tools for building whole-program (or
@ -252,6 +253,11 @@ produces the bitcode. This can be fulfilled by setting the
`LLVM_BITCODE_GENERATION_FLAGS` environment variable to the desired
flags, for example `"-flto -fwhole-program-vtables"`.
In other situations it is desirable to pass certain flags to `llvm-link` in the step
that merges multiple individual bitcode files together (i.e., within `get-bc`).
This can be fulfilled by setting the `LLVM_LINK_FLAGS` environment variable to
the desired flags, for example `"-internalize -only-needed"`.
## Beware of link time optimization.
If the package you are building happens to take advantage of recent `clang` developments

6
shared/environment.go
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@ -68,6 +68,9 @@ var LLVMARName string
//LLVMLINKName is the user configured name of the llvm-link.
var LLVMLINKName string
//LLVMLINKFlags is the user configured list of flags to append to llvm-link.
var LLVMLINKFlags []string
//LLVMConfigureOnly is the user configured flag indicating a single pass mode is required.
var LLVMConfigureOnly string
@ -99,6 +102,7 @@ const (
envf = "LLVM_F_NAME"
envar = "LLVM_AR_NAME"
envlnk = "LLVM_LINK_NAME"
envlnkflgs = "LLVM_LINK_FLAGS"
envcfg = "WLLVM_CONFIGURE_ONLY"
envbc = "WLLVM_BC_STORE"
envlvl = "WLLVM_OUTPUT_LEVEL"
@ -142,6 +146,7 @@ func ResetEnvironment() {
LLVMFName = ""
LLVMARName = ""
LLVMLINKName = ""
LLVMLINKFlags = []string{}
LLVMConfigureOnly = ""
LLVMBitcodeStorePath = ""
LLVMLoggingLevel = ""
@ -160,6 +165,7 @@ func FetchEnvironment() {
LLVMFName = os.Getenv(envf)
LLVMARName = os.Getenv(envar)
LLVMLINKName = os.Getenv(envlnk)
LLVMLINKFlags = strings.Fields(os.Getenv(envlnkflgs))
LLVMConfigureOnly = os.Getenv(envcfg)
LLVMBitcodeStorePath = os.Getenv(envbc)

9
shared/extractor.go
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@ -661,6 +661,10 @@ func linkBitcodeFilesIncrementally(ea ExtractionArgs, filesToLink []string, argM
if ea.Verbose {
linkArgs = append(linkArgs, "-v")
}
// Append any custom llvm-link flags requested by the user.
// We only do this for the last llvm-link invocation.
linkArgs = append(linkArgs, LLVMLINKFlags...)
linkArgs = append(linkArgs, tmpFileList...)
linkArgs = append(linkArgs, "-o", ea.OutputFile)
@ -682,10 +686,15 @@ func linkBitcodeFiles(ea ExtractionArgs, filesToLink []string) (success bool) {
if ea.Verbose {
linkArgs = append(linkArgs, "-v")
}
if getsize(filesToLink) > argMax { //command line size too large for the OS (necessitated by chromium)
return linkBitcodeFilesIncrementally(ea, filesToLink, argMax, linkArgs)
}
var err error
// Append any custom llvm-link flags requested by the user.
// N.B. that we do this specially for the incremental link case.
linkArgs = append(linkArgs, LLVMLINKFlags...)
linkArgs = append(linkArgs, "-o", ea.OutputFile)
linkArgs = append(linkArgs, filesToLink...)
success, err = execCmd(ea.LlvmLinkerName, linkArgs, "")