Add the new @llvm.nacl.atomic.fence.all intrinsic

This is a follow-up to:
  https://codereview.chromium.org/22240002/
And requires the Clang changes from:
  https://codereview.chromium.org/22294002/

This new intrinsic represents ``asm("":::"~{memory}")`` as well as ``__sync_synchronize()``, and in IR it corresponds to a sequentially-consistent fence surrounded by ``call void asm sideeffect "", "~{memory}"()``.

R=jvoung@chromium.org
TEST= ninja check-all
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3475

Review URL: https://codereview.chromium.org/22474008

1 files changed, 5 insertions, 3 deletions

diff --git a/lib/Transforms/NaCl/PNaClABISimplify.cpp b/lib/Transforms/NaCl/PNaClABISimplify.cpp
index 4f8e0e4f87..f662ada99a 100644
--- a/lib/Transforms/NaCl/PNaClABISimplify.cpp
+++ b/lib/Transforms/NaCl/PNaClABISimplify.cpp
@@ -30,10 +30,8 @@ void llvm::PNaClABISimplifyAddPreOptPasses(PassManager &PM) {
   // LowerExpect converts Intrinsic::expect into branch weights,
   // which can then be removed after BlockPlacement.
   PM.add(createLowerExpectIntrinsicPass());
-  // Rewrite unsupported intrinsics and inline assembly directives to
-  // simpler and portable constructs.
+  // Rewrite unsupported intrinsics to simpler and portable constructs.
   PM.add(createRewriteLLVMIntrinsicsPass());
-  PM.add(createRewriteAsmDirectivesPass());
   // LowerInvoke prevents use of C++ exception handling, which is not
   // yet supported in the PNaCl ABI.
   PM.add(createLowerInvokePass());
@@ -98,6 +96,10 @@ void llvm::PNaClABISimplifyAddPostOptPasses(PassManager &PM) {
   PM.add(createExpandGetElementPtrPass());
   // Rewrite atomic and volatile instructions with intrinsic calls.
   PM.add(createRewriteAtomicsPass());
+  // Remove ``asm("":::"memory")``. This must occur after rewriting
+  // atomics: a ``fence seq_cst`` surrounded by ``asm("":::"memory")``
+  // has special meaning and is translated differently.
+  PM.add(createRemoveAsmMemoryPass());
   // ReplacePtrsWithInts assumes that getelementptr instructions and
   // ConstantExprs have already been expanded out.
   PM.add(createReplacePtrsWithIntsPass());