[Driver] Pass --fix-cortex-a53-843419 automatically on Fuchsia

When targeting cortex-a53, set this linker flag rather than relying
on the toolchain users to do it in their build.

Differential Revision: https://reviews.llvm.org/D114023

Author: petrhosek

clang/lib/Driver/ToolChains/Fuchsia.cpp

@@ -37,6 +37,8 @@ void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       static_cast<const toolchains::Fuchsia &>(getToolChain());
   const Driver &D = ToolChain.getDriver();
 
+  const llvm::Triple &Triple = ToolChain.getEffectiveTriple();
+
   ArgStringList CmdArgs;
 
   // Silence warning for "clang -g foo.o -o foo"
@@ -84,6 +86,12 @@ void fuchsia::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("--hash-style=gnu");
   }
 
+  if (ToolChain.getArch() == llvm::Triple::aarch64) {
+    std::string CPU = getCPUName(D, Args, Triple);
+    if (CPU.empty() || CPU == "generic" || CPU == "cortex-a53")
+      CmdArgs.push_back("--fix-cortex-a53-843419");
+  }
+
   CmdArgs.push_back("--eh-frame-hdr");
 
   if (Args.hasArg(options::OPT_static))

clang/test/Driver/fuchsia.c

@@ -41,6 +41,7 @@
 // CHECK: "-pie"
 // CHECK: "--build-id"
 // CHECK: "--hash-style=gnu"
+// CHECK-AARCH64: "--fix-cortex-a53-843419"
 // CHECK: "-dynamic-linker" "ld.so.1"
 // CHECK: Scrt1.o
 // CHECK-NOT: crti.o