Enable PIE for CloudABI.

As we're currently working on making CloudABI executables easier to
emulate in userspace (e.g., on OS X and Windows), it makes a whole lot
of sense to build these using PIE. By using PIE, they can simply be
loaded into the existing process address space without clashes.

PIE support got added to CloudABI's C library and seems to work pretty
well. CloudABI does not make use of an ld.so, so the binary's _start()
has all the logic in it to do the relocations.

Now that all but one bug in LLD relating to PIE support have been
squashed (and a patch for that is already in code review), I'd like to
go ahead and force the use of PIE for Clang 3.9. When released, we'll
also switch over to using LLD exclusively.

llvm-svn: 265546

4 files changed, 11 insertions, 5 deletions

diff --git a/clang/lib/Driver/ToolChains.h b/clang/lib/Driver/ToolChains.h
index d0418349bfa..e7992170cc8 100644
--- a/clang/lib/Driver/ToolChains.h
+++ b/clang/lib/Driver/ToolChains.h
@@ -617,7 +617,7 @@ public:
   void AddCXXStdlibLibArgs(const llvm::opt::ArgList &Args,
                            llvm::opt::ArgStringList &CmdArgs) const override;
 
-  bool isPIEDefault() const override { return false; }
+  bool isPIEDefault() const override { return true; }
 
   SanitizerMask getSupportedSanitizers() const override;
   SanitizerMask getDefaultSanitizers() const override;
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 6be28290a7f..a585918aa28 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -7110,6 +7110,12 @@ void cloudabi::Linker::ConstructJob(Compilation &C, const JobAction &JA,
 
   // CloudABI only supports static linkage.
   CmdArgs.push_back("-Bstatic");
+
+  // CloudABI uses Position Independent Executables exclusively.
+  CmdArgs.push_back("-pie");
+  CmdArgs.push_back("--no-dynamic-linker");
+  CmdArgs.push_back("-zrelro");
+
   CmdArgs.push_back("--eh-frame-hdr");
   CmdArgs.push_back("--gc-sections");
 
diff --git a/clang/test/Driver/cloudabi.c b/clang/test/Driver/cloudabi.c
index 2f1f9852b0a..7a72f618951 100644
--- a/clang/test/Driver/cloudabi.c
+++ b/clang/test/Driver/cloudabi.c
@@ -1,8 +1,8 @@
 // RUN: %clang %s -### -target x86_64-unknown-cloudabi 2>&1 | FileCheck %s -check-prefix=SAFESTACK
 // SAFESTACK: "-cc1" "-triple" "x86_64-unknown-cloudabi" {{.*}} "-ffunction-sections" "-fdata-sections" {{.*}} "-fsanitize=safe-stack"
-// SAFESTACK: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc" "-lcompiler_rt" "crtend.o"
+// SAFESTACK: "-Bstatic" "-pie" "--no-dynamic-linker" "-zrelro" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc" "-lcompiler_rt" "crtend.o"
 
 // RUN: %clang %s -### -target x86_64-unknown-cloudabi -fno-sanitize=safe-stack 2>&1 | FileCheck %s -check-prefix=NOSAFESTACK
 // NOSAFESTACK: "-cc1" "-triple" "x86_64-unknown-cloudabi" {{.*}} "-ffunction-sections" "-fdata-sections"
 // NOSAFESTACK-NOT: "-fsanitize=safe-stack"
-// NOSAFESTACK: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc" "-lcompiler_rt" "crtend.o"
+// NOSAFESTACK: "-Bstatic" "-pie" "--no-dynamic-linker" "-zrelro" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc" "-lcompiler_rt" "crtend.o"
diff --git a/clang/test/Driver/cloudabi.cpp b/clang/test/Driver/cloudabi.cpp
index 9c1b6d091c1..dd52ac36acc 100644
--- a/clang/test/Driver/cloudabi.cpp
+++ b/clang/test/Driver/cloudabi.cpp
@@ -1,8 +1,8 @@
 // RUN: %clangxx %s -### -target x86_64-unknown-cloudabi 2>&1 | FileCheck %s -check-prefix=SAFESTACK
 // SAFESTACK: "-cc1" "-triple" "x86_64-unknown-cloudabi" {{.*}} "-ffunction-sections" "-fdata-sections" {{.*}} "-fsanitize=safe-stack"
-// SAFESTACK: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc++" "-lc++abi" "-lunwind" "-lc" "-lcompiler_rt" "crtend.o"
+// SAFESTACK: "-Bstatic" "-pie" "--no-dynamic-linker" "-zrelro" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc++" "-lc++abi" "-lunwind" "-lc" "-lcompiler_rt" "crtend.o"
 
 // RUN: %clangxx %s -### -target x86_64-unknown-cloudabi -fno-sanitize=safe-stack 2>&1 | FileCheck %s -check-prefix=NOSAFESTACk
 // NOSAFESTACK: "-cc1" "-triple" "x86_64-unknown-cloudabi" {{.*}} "-ffunction-sections" "-fdata-sections"
 // NOSAFESTACK-NOT: "-fsanitize=safe-stack"
-// NOSAFESTACk: "-Bstatic" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc++" "-lc++abi" "-lunwind" "-lc" "-lcompiler_rt" "crtend.o"
+// NOSAFESTACk: "-Bstatic" "-pie" "--no-dynamic-linker" "-zrelro" "--eh-frame-hdr" "--gc-sections" "-o" "a.out" "crt0.o" "crtbegin.o" "{{.*}}" "{{.*}}" "-lc++" "-lc++abi" "-lunwind" "-lc" "-lcompiler_rt" "crtend.o"