[Clang][Driver] Ensure clang can construct toolchain target names

[mincrmatt12]

This adds an extra validation step to ToolChain::getTargetAndModeFromProgramName to actually try constructing the target info for the triple it deduces, instead of just relying on the LLVM target registry.

Some targets, like xtensa, are supported by LLVM but are not supported by clang, so just checking the LLVM registry causes inconsistency.

This is based on the discussion from clangd/clangd#2184 (and indeed would solve that issue) - the approach here of "construct the target info and check for null" is taken from clangd.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Matthew Mirvish (mincrmatt12)

Changes

This adds an extra validation step to ToolChain::getTargetAndModeFromProgramName to actually try constructing the target info for the triple it deduces, instead of just relying on the LLVM target registry.

Some targets, like xtensa, are supported by LLVM but are not supported by clang, so just checking the LLVM registry causes inconsistency.

This is based on the discussion from clangd/clangd#2184 (and indeed would solve that issue) - the approach here of "construct the target info and check for null" is taken from clangd.

---

Full diff: https://github.com/llvm/llvm-project/pull/115798.diff

1 Files Affected:

• (modified) clang/lib/Driver/ToolChain.cpp (+15)

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp index 646dbc0faf5a9f..e094a5fd0267f3 100644 --- a/clang/lib/Driver/ToolChain.cpp +++ b/clang/lib/Driver/ToolChain.cpp @@ -16,6 +16,8 @@ #include "ToolChains/InterfaceStubs.h" #include "clang/Basic/ObjCRuntime.h" #include "clang/Basic/Sanitizers.h" +#include "clang/Basic/TargetInfo.h" +#include "clang/Basic/TargetOptions.h" #include "clang/Config/config.h" #include "clang/Driver/Action.h" #include "clang/Driver/Driver.h" @@ -496,8 +498,21 @@ ToolChain::getTargetAndModeFromProgramName(StringRef PN) { StringRef Prefix(ProgName); Prefix = Prefix.slice(0, LastComponent); std::string IgnoredError; + + // First, check if the target is a supported LLVM target. bool IsRegistered = llvm::TargetRegistry::lookupTarget(std::string(Prefix), IgnoredError); + // If so, further check that clang is able to use it as a target. + if (IsRegistered) { + std::shared_ptr<TargetOptions> TargetOpts(new TargetOptions); + TargetOpts->Triple = Prefix.str(); + DiagnosticsEngine Diags(new DiagnosticIDs, new DiagnosticOptions, + new IgnoringDiagConsumer); + llvm::IntrusiveRefCntPtr<TargetInfo> Target = + clang::TargetInfo::CreateTargetInfo(Diags, TargetOpts); + if (!Target) + IsRegistered = false; + } return ParsedClangName{std::string(Prefix), ModeSuffix, DS->ModeFlag, IsRegistered}; }