optimize position independent code in executables

Position independent code has fewer requirements in executables, so pass
the appropriate flag to LLVM in order to allow more optimization. At the
moment this means faster thread-local storage.

diff --git a/src/librustc/back/write.rs b/src/librustc/back/write.rs
index 603f5ed227cdf8e0621701cb6d4d100d0f06abdc..f1cd8b52e5ed3103fa8e2b0a09c87dcecfdae0d0 100644 (file)
--- a/src/librustc/back/write.rs
+++ b/src/librustc/back/write.rs
@@ -34,7 +34,6 @@
 use std::task::TaskBuilder;
 use libc::{c_uint, c_int, c_void};
 
-
 #[deriving(Clone, PartialEq, PartialOrd, Ord, Eq)]
 pub enum OutputType {
     OutputTypeBitcode,
@@ -44,7 +43,6 @@ pub enum OutputType {
     OutputTypeExe,
 }
 
-
 pub fn llvm_err(handler: &diagnostic::Handler, msg: String) -> ! {
     unsafe {
         let cstr = llvm::LLVMRustGetLastError();
@@ -202,6 +200,10 @@ fn create_target_machine(sess: &Session) -> TargetMachineRef {
                      (sess.targ_cfg.os == abi::OsMacos &&
                       sess.targ_cfg.arch == abi::X86_64);
 
+    let any_library = sess.crate_types.borrow().iter().any(|ty| {
+        *ty != config::CrateTypeExecutable
+    });
+
     // OSX has -dead_strip, which doesn't rely on ffunction_sections
     // FIXME(#13846) this should be enabled for windows
     let ffunction_sections = sess.targ_cfg.os != abi::OsMacos &&
@@ -240,6 +242,7 @@ fn create_target_machine(sess: &Session) -> TargetMachineRef {
                         true /* EnableSegstk */,
                         use_softfp,
                         no_fp_elim,
+                        !any_library && reloc_model == llvm::RelocPIC,
                         ffunction_sections,
                         fdata_sections,
                     )

diff --git a/src/librustc_llvm/lib.rs b/src/librustc_llvm/lib.rs
index e1576e37cc64cea92843a451d7fe83eacfc02437..a1a6412af1135605891132e4df57ad1f20788541 100644 (file)
--- a/src/librustc_llvm/lib.rs
+++ b/src/librustc_llvm/lib.rs
@@ -353,6 +353,7 @@ pub enum CodeGenOptLevel {
     CodeGenLevelAggressive = 3,
 }
 
+#[deriving(PartialEq)]
 #[repr(C)]
 pub enum RelocMode {
     RelocDefault = 0,
@@ -1907,6 +1908,7 @@ pub fn LLVMRustCreateTargetMachine(Triple: *const c_char,
                                        EnableSegstk: bool,
                                        UseSoftFP: bool,
                                        NoFramePointerElim: bool,
+                                       PositionIndependentExecutable: bool,
                                        FunctionSections: bool,
                                        DataSections: bool) -> TargetMachineRef;
     pub fn LLVMRustDisposeTargetMachine(T: TargetMachineRef);

diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index eb074001d5854bf42e5d4d627a624f56b30196c2..ce3090390db8e73ac904ee6fc6f742a2960fb8dc 100644 (file)
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -71,6 +71,7 @@ LLVMRustCreateTargetMachine(const char *triple,
                             bool EnableSegmentedStacks,
                             bool UseSoftFloat,
                             bool NoFramePointerElim,
+                            bool PositionIndependentExecutable,
                             bool FunctionSections,
                             bool DataSections) {
     std::string Error;
@@ -83,6 +84,7 @@ LLVMRustCreateTargetMachine(const char *triple,
     }
 
     TargetOptions Options;
+    Options.PositionIndependentExecutable = PositionIndependentExecutable;
     Options.NoFramePointerElim = NoFramePointerElim;
 #if LLVM_VERSION_MINOR < 5
     Options.EnableSegmentedStacks = EnableSegmentedStacks;