[WebAssembly] Limit PIC support to the Emscripten target

The current PIC support currently only works with Emscripten, so
disable it for other targets.

This is the PIC portion of https://reviews.llvm.org/D62542.

Reviewed By: dschuff, sbc100

llvm-svn: 362638

1 files changed, 11 insertions, 2 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index 8b73e827856..937d272d213 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -83,13 +83,22 @@ extern "C" void LLVMInitializeWebAssemblyTarget() {
 // WebAssembly Lowering public interface.
 //===----------------------------------------------------------------------===//
 
-static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM) {
+static Reloc::Model getEffectiveRelocModel(Optional<Reloc::Model> RM,
+                                           const Triple &TT) {
   if (!RM.hasValue()) {
     // Default to static relocation model.  This should always be more optimial
     // than PIC since the static linker can determine all global addresses and
     // assume direct function calls.
     return Reloc::Static;
   }
+
+  if (!TT.isOSEmscripten()) {
+    // Relocation modes other than static are currently implemented in a way
+    // that only works for Emscripten, so disable them if we aren't targeting
+    // Emscripten.
+    return Reloc::Static;
+  }
+
   return *RM;
 }
 
@@ -102,7 +111,7 @@ WebAssemblyTargetMachine::WebAssemblyTargetMachine(
     : LLVMTargetMachine(T,
                         TT.isArch64Bit() ? "e-m:e-p:64:64-i64:64-n32:64-S128"
                                          : "e-m:e-p:32:32-i64:64-n32:64-S128",
-                        TT, CPU, FS, Options, getEffectiveRelocModel(RM),
+                        TT, CPU, FS, Options, getEffectiveRelocModel(RM, TT),
                         getEffectiveCodeModel(CM, CodeModel::Large), OL),
       TLOF(new WebAssemblyTargetObjectFile()) {
   // WebAssembly type-checks instructions, but a noreturn function with a return