[WebAssembly] Don't use default GetLinkerPath

We can't (don't want to) honor the same set of "-fuse-ld" flags with
WebAssembly since the ELF linkers (ld.lld, ld.gnu, etc) don't work with
wasm object files.

Instead we implement our own linker finding logic, similar or other
non-ELF platforms like MSVC.

We've had a few issues with CLANG_DEFAULT_LINKER overriding the
WebAssembly linker which doesn't make sense since there is no generic
linker that can handle WebAssembly today.

Differential Revision: https://reviews.llvm.org/D59743

llvm-svn: 356953

4 files changed, 31 insertions, 9 deletions

diff --git a/clang/lib/Driver/ToolChains/WebAssembly.cpp b/clang/lib/Driver/ToolChains/WebAssembly.cpp
index b69588d4c1e..27d6cbfe7a4 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.cpp
+++ b/clang/lib/Driver/ToolChains/WebAssembly.cpp
@@ -12,6 +12,8 @@
 #include "clang/Driver/Driver.h"
 #include "clang/Driver/DriverDiagnostic.h"
 #include "clang/Driver/Options.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Option/ArgList.h"
 
 using namespace clang::driver;
@@ -36,6 +38,25 @@ bool wasm::Linker::isLinkJob() const { return true; }
 
 bool wasm::Linker::hasIntegratedCPP() const { return false; }
 
+std::string wasm::Linker::getLinkerPath(const ArgList &Args) const {
+  const ToolChain &ToolChain = getToolChain();
+  if (const Arg* A = Args.getLastArg(options::OPT_fuse_ld_EQ)) {
+    StringRef UseLinker = A->getValue();
+    if (!UseLinker.empty()) {
+      if (llvm::sys::path::is_absolute(UseLinker) &&
+          llvm::sys::fs::can_execute(UseLinker))
+        return UseLinker;
+
+      // Accept 'lld', and 'ld' as aliases for the default linker
+      if (UseLinker != "lld" && UseLinker != "ld")
+        ToolChain.getDriver().Diag(diag::err_drv_invalid_linker_name)
+            << A->getAsString(Args);
+    }
+  }
+
+  return ToolChain.getDefaultLinker();
+}
+
 void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                 const InputInfo &Output,
                                 const InputInfoList &Inputs,
@@ -43,7 +64,7 @@ void wasm::Linker::ConstructJob(Compilation &C, const JobAction &JA,
                                 const char *LinkingOutput) const {
 
   const ToolChain &ToolChain = getToolChain();
-  const char *Linker = Args.MakeArgString(ToolChain.GetLinkerPath());
+  const char *Linker = Args.MakeArgString(getLinkerPath(Args));
   ArgStringList CmdArgs;
 
   if (Args.hasArg(options::OPT_s))
diff --git a/clang/lib/Driver/ToolChains/WebAssembly.h b/clang/lib/Driver/ToolChains/WebAssembly.h
index 2d9210ac04c..75ae1fc5a09 100644
--- a/clang/lib/Driver/ToolChains/WebAssembly.h
+++ b/clang/lib/Driver/ToolChains/WebAssembly.h
@@ -23,6 +23,7 @@ public:
   explicit Linker(const ToolChain &TC);
   bool isLinkJob() const override;
   bool hasIntegratedCPP() const override;
+  std::string getLinkerPath(const llvm::opt::ArgList &Args) const;
   void ConstructJob(Compilation &C, const JobAction &JA,
                     const InputInfo &Output, const InputInfoList &Inputs,
                     const llvm::opt::ArgList &TCArgs,
diff --git a/clang/test/Driver/wasm-toolchain.c b/clang/test/Driver/wasm-toolchain.c
index 893fd2510d3..e90785b42b7 100644
--- a/clang/test/Driver/wasm-toolchain.c
+++ b/clang/test/Driver/wasm-toolchain.c
@@ -12,25 +12,25 @@
 
 // A basic C link command-line with unknown OS.
 
-// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo -fuse-ld=wasm-ld %s 2>&1 | FileCheck -check-prefix=LINK %s
+// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK %s
 // LINK: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK: wasm-ld{{.*}}" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C link command-line with optimization with unknown OS.
 
-// RUN: %clang -### -O2 -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo -fuse-ld=wasm-ld %s 2>&1 | FileCheck -check-prefix=LINK_OPT %s
+// RUN: %clang -### -O2 -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK_OPT %s
 // LINK_OPT: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_OPT: wasm-ld{{.*}}" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C link command-line with known OS.
 
-// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo -fuse-ld=wasm-ld %s 2>&1 | FileCheck -check-prefix=LINK_KNOWN %s
+// RUN: %clang -### -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK_KNOWN %s
 // LINK_KNOWN: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_KNOWN: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi-musl" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C link command-line with optimization with known OS.
 
-// RUN: %clang -### -O2 -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo -fuse-ld=wasm-ld %s 2>&1 | FileCheck -check-prefix=LINK_OPT_KNOWN %s
+// RUN: %clang -### -O2 -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo %s 2>&1 | FileCheck -check-prefix=LINK_OPT_KNOWN %s
 // LINK_OPT_KNOWN: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_OPT_KNOWN: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi-musl" "crt1.o" "[[temp]]" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
diff --git a/clang/test/Driver/wasm-toolchain.cpp b/clang/test/Driver/wasm-toolchain.cpp
index 447b1a0a560..e29b693d681 100644
--- a/clang/test/Driver/wasm-toolchain.cpp
+++ b/clang/test/Driver/wasm-toolchain.cpp
@@ -12,25 +12,25 @@
 
 // A basic C++ link command-line with unknown OS.
 
-// RUN: %clangxx -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo -fuse-ld=wasm-ld --stdlib=c++ %s 2>&1 | FileCheck -check-prefix=LINK %s
+// RUN: %clangxx -### -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo --stdlib=c++ %s 2>&1 | FileCheck -check-prefix=LINK %s
 // LINK: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK: wasm-ld{{.*}}" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C++ link command-line with optimization with unknown OS.
 
-// RUN: %clangxx -### -O2 -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo %s --stdlib=c++ -fuse-ld=wasm-ld 2>&1 | FileCheck -check-prefix=LINK_OPT %s
+// RUN: %clangxx -### -O2 -no-canonical-prefixes -target wasm32-unknown-unknown --sysroot=/foo %s --stdlib=c++ 2>&1 | FileCheck -check-prefix=LINK_OPT %s
 // LINK_OPT: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_OPT: wasm-ld{{.*}}" "-L/foo/lib" "crt1.o" "[[temp]]" "-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C++ link command-line with known OS.
 
-// RUN: %clangxx -### -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo -fuse-ld=wasm-ld --stdlib=c++ %s 2>&1 | FileCheck -check-prefix=LINK_KNOWN %s
+// RUN: %clangxx -### -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo --stdlib=c++ %s 2>&1 | FileCheck -check-prefix=LINK_KNOWN %s
 // LINK_KNOWN: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_KNOWN: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi-musl" "crt1.o" "[[temp]]" "-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"
 
 // A basic C++ link command-line with optimization with known OS.
 
-// RUN: %clangxx -### -O2 -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo %s --stdlib=c++ -fuse-ld=wasm-ld 2>&1 | FileCheck -check-prefix=LINK_OPT_KNOWN %s
+// RUN: %clangxx -### -O2 -no-canonical-prefixes -target wasm32-unknown-wasi-musl --sysroot=/foo %s --stdlib=c++ 2>&1 | FileCheck -check-prefix=LINK_OPT_KNOWN %s
 // LINK_OPT_KNOWN: clang{{.*}}" "-cc1" {{.*}} "-o" "[[temp:[^"]*]]"
 // LINK_OPT_KNOWN: wasm-ld{{.*}}" "-L/foo/lib/wasm32-wasi-musl" "crt1.o" "[[temp]]" "-lc++" "-lc++abi" "-lc" "{{.*[/\\]}}libclang_rt.builtins-wasm32.a" "-o" "a.out"