[PATCH] D92677: Provide default location of sysroot for Baremetal toolchain.

[Hafiz Abid Qadeer via Phabricator via cfe-commits]

abidh created this revision.
abidh added reviewers: mcarrasco, jroelofs.
abidh added a project: clang.
Herald added subscribers: s.egerton, PkmX, simoncook, kristof.beyls.
abidh requested review of this revision.
Herald added a subscriber: cfe-commits.

Currently, Baremetal toolchain requires user to pass a sysroot location
using a --sysroot flag. This is not very convenient for the user. It also
creates problem for toolchain vendors who don't have a fixed location to
put the sysroot bits.

Clang does provide 'DEFAULT_SYSROOT' which can be used by the toolchain
builder to provide the default location. But it does not work if toolchain
is targeting multiple targets e.g. arm-none-eabi/riscv64-unknown-elf which
clang is capable of doing.

This patch tries to solve this problem by providing a default location of
the toolchain if user does not explicitly provides --sysroot. The exact
location and name can be different but it should fulfill these conditions:

1. The sysroot path should have a target triple element so that multi-target

toolchain problem (as I described above) could be addressed.

2. The location should not be $TOP/$Triple as this is used by gcc generally

and will be a problem for installing both gcc and clang based toolchain at
the same location.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92677

Files:
  clang/lib/Driver/ToolChains/BareMetal.cpp
  clang/lib/Driver/ToolChains/BareMetal.h
  clang/test/Driver/baremetal-sysroot.cpp


Index: clang/test/Driver/baremetal-sysroot.cpp
===================================================================
--- /dev/null
+++ clang/test/Driver/baremetal-sysroot.cpp
@@ -0,0 +1,22 @@
+// REQUIRES: shell
+// UNSUPPORTED: system-windows
+
+// Test that when a --sysroot is not provided, driver picks the default
+// location correctly if available.
+
+// RUN: rm -rf %T/baremetal_default_sysroot
+// RUN: mkdir -p %T/baremetal_default_sysroot/bin
+// RUN: mkdir -p %T/baremetal_default_sysroot/lib/clang-runtimes/armv6m-none-eabi
+// RUN: ln -s %clang %T/baremetal_default_sysroot/bin/clang
+
+// RUN: %T/baremetal_default_sysroot/bin/clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -target armv6m-none-eabi \
+// RUN:   | FileCheck --check-prefix=CHECK-V6M-C %s
+// CHECK-V6M-C: "{{.*}}clang{{.*}}" "-cc1" "-triple" "thumbv6m-none-unknown-eabi"
+// CHECK-V6M-C-SAME: "-internal-isystem" "{{.*}}/baremetal_default_sysroot{{[/\\]+}}bin{{[/\\]+}}..{{[/\\]+}}lib{{[/\\]+}}clang-runtimes{{[/\\]+}}armv6m-none-eabi{{[/\\]+}}include{{[/\\]+}}c++{{[/\\]+}}v1"
+// CHECk-V6M-C-SAME: "-internal-isystem" "{{.*}}/baremetal_default_sysroot{{[/\\]+}}bin{{[/\\]+}}..{{[/\\]+}}lib{{[/\\]+}}clang-runtimes{{[/\\]+}}armv6m-none-eabi{{[/\\]+}}include"
+// CHECK-V6M-C-SAME: "-x" "c++" "{{.*}}baremetal-sysroot.cpp"
+// CHECK-V6M-C-NEXT: "{{[^"]*}}ld{{(\.(lld|bfd|gold))?}}{{(\.exe)?}}" "{{.*}}.o" "-Bstatic"
+// CHECK-V6M-C-SAME: "-L{{.*}}/baremetal_default_sysroot{{[/\\]+}}bin{{[/\\]+}}..{{[/\\]+}}lib{{[/\\]+}}clang-runtimes{{[/\\]+}}armv6m-none-eabi{{[/\\]+}}lib"
+// CHECK-V6M-C-SAME: "-lc" "-lm" "-lclang_rt.builtins-armv6m"
+// CHECK-V6M-C-SAME: "-o" "{{.*}}.o"
Index: clang/lib/Driver/ToolChains/BareMetal.h
===================================================================
--- clang/lib/Driver/ToolChains/BareMetal.h
+++ clang/lib/Driver/ToolChains/BareMetal.h
@@ -67,6 +67,7 @@
                            llvm::opt::ArgStringList &CmdArgs) const override;
   void AddLinkRuntimeLib(const llvm::opt::ArgList &Args,
                          llvm::opt::ArgStringList &CmdArgs) const;
+  std::string computeSysRoot() const override;
 };
 
 } // namespace toolchains
Index: clang/lib/Driver/ToolChains/BareMetal.cpp
===================================================================
--- clang/lib/Driver/ToolChains/BareMetal.cpp
+++ clang/lib/Driver/ToolChains/BareMetal.cpp
@@ -33,7 +33,7 @@
   getProgramPaths().push_back(getDriver().getInstalledDir());
   if (getDriver().getInstalledDir() != getDriver().Dir)
     getProgramPaths().push_back(getDriver().Dir);
-  SmallString<128> SysRoot(getDriver().SysRoot);
+  SmallString<128> SysRoot(computeSysRoot());
   if (!SysRoot.empty()) {
     llvm::sys::path::append(SysRoot, "lib");
     getFilePaths().push_back(std::string(SysRoot));
@@ -94,6 +94,20 @@
   return std::string(Dir.str());
 }
 
+std::string BareMetal::computeSysRoot() const {
+  if (!getDriver().SysRoot.empty())
+    return getDriver().SysRoot;
+
+  SmallString<128> SysRootDir;
+  llvm::sys::path::append(SysRootDir, getDriver().Dir, "../lib/clang-runtimes",
+                          getDriver().getTargetTriple());
+
+  if (!llvm::sys::fs::exists(SysRootDir))
+    return std::string();
+
+  return std::string(SysRootDir.str());
+}
+
 void BareMetal::AddClangSystemIncludeArgs(const ArgList &DriverArgs,
                                           ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdinc))
@@ -106,7 +120,7 @@
   }
 
   if (!DriverArgs.hasArg(options::OPT_nostdlibinc)) {
-    SmallString<128> Dir(getDriver().SysRoot);
+    SmallString<128> Dir(computeSysRoot());
     if (!Dir.empty()) {
       llvm::sys::path::append(Dir, "include");
       addSystemInclude(DriverArgs, CC1Args, Dir.str());
@@ -127,7 +141,7 @@
       DriverArgs.hasArg(options::OPT_nostdincxx))
     return;
 
-  StringRef SysRoot = getDriver().SysRoot;
+  std::string SysRoot(computeSysRoot());
   if (SysRoot.empty())
     return;
 


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