[clang] [RISCV] Implement multi-lib reuse rule for RISC-V bare-metal toolchain (PR #73765)
Craig Topper via cfe-commits
cfe-commits at lists.llvm.org
Wed Dec 6 22:03:10 PST 2023
================
@@ -1715,6 +1716,130 @@ static void findCSKYMultilibs(const Driver &D, const llvm::Triple &TargetTriple,
Result.Multilibs = CSKYMultilibs;
}
+/// Extend the multi-lib re-use selection mechanism for RISC-V.
+/// This function will try to re-use multi-lib if they are compatible.
+/// Definition of compatible:
+/// - ABI must be the same.
+/// - multi-lib is a subset of current arch, e.g. multi-lib=march=rv32im
+/// is a subset of march=rv32imc.
+/// - march that contains atomic extension can't reuse multi-lib that
+/// doesn't have atomic, vice versa. e.g. multi-lib=march=rv32im and
+/// march=rv32ima are not compatible, because software and hardware
+/// atomic operation can't work together correctly.
+static bool
+RISCVMultilibSelect(const MultilibSet &RISCVMultilibSet, StringRef Arch,
+ const Multilib::flags_list &Flags,
+ llvm::SmallVector<Multilib> &SelectedMultilibs) {
+ // Try to find the perfect matching multi-lib first.
+ if (RISCVMultilibSet.select(Flags, SelectedMultilibs))
+ return true;
+
+ Multilib::flags_list NewFlags;
+ std::vector<MultilibBuilder> NewMultilibs;
+
+ llvm::Expected<std::unique_ptr<llvm::RISCVISAInfo>> ParseResult =
+ llvm::RISCVISAInfo::parseArchString(
+ Arch, /*EnableExperimentalExtension=*/true,
+ /*ExperimentalExtensionVersionCheck=*/false);
+ if (!ParseResult) {
+ // Ignore any error here, we assume it will be handled in another place.
+ consumeError(ParseResult.takeError());
+ return false;
+ }
+
+ auto &ISAInfo = *ParseResult;
+
+ addMultilibFlag(ISAInfo->getXLen() == 32, "-m32", NewFlags);
+ addMultilibFlag(ISAInfo->getXLen() == 64, "-m64", NewFlags);
+
+ // Collect all flags except march=*
+ for (StringRef Flag : Flags) {
+ if (Flag.startswith("!march=") || Flag.startswith("-march="))
+ continue;
+
+ NewFlags.push_back(Flag.str());
+ }
+
+ llvm::StringSet<> AllArchExts;
+ // Reconstruct multi-lib list, and break march option into separated
+ // extension. e.g. march=rv32im -> +i +m
+ for (auto M : RISCVMultilibSet) {
+ bool Skip = false;
+
+ MultilibBuilder NewMultilib =
+ MultilibBuilder(M.gccSuffix(), M.osSuffix(), M.includeSuffix());
+ for (StringRef Flag : M.flags()) {
+ // Add back the all option except -march.
----------------
topperc wrote:
`Add back all flags except -march.`
https://github.com/llvm/llvm-project/pull/73765
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