PNaCl: Add "-pnacl-abi-simplify-{pre,post}opt" meta-passes to "opt"

These meta-passes will be used to replace the pass lists that are
currently in the pnacl-ld.py driver script in the NaCl repo.

I've moved the comments across from pnacl-ld.py and added a couple
more comments for ExpandByVal and StripMetadata.

Fix the declaration of createResolveAliasesPass().

BUG=https://code.google.com/p/nativeclient/issues/detail?id=3435
TEST=new *.ll tests + tested with change to pnacl-ld.py

Review URL: https://codereview.chromium.org/15669002

1 files changed, 65 insertions, 0 deletions

diff --git a/lib/Transforms/NaCl/PNaClABISimplify.cpp b/lib/Transforms/NaCl/PNaClABISimplify.cpp
new file mode 100644
index 0000000000..9d7713139a
--- /dev/null
+++ b/lib/Transforms/NaCl/PNaClABISimplify.cpp
@@ -0,0 +1,65 @@
+//===-- PNaClABISimplify.cpp - Lists PNaCl ABI simplification passes ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the meta-passes "-pnacl-abi-simplify-preopt"
+// and "-pnacl-abi-simplify-postopt".  It lists their constituent
+// passes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/NaCl.h"
+#include "llvm/PassManager.h"
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/NaCl.h"
+#include "llvm/Transforms/Scalar.h"
+
+using namespace llvm;
+
+void llvm::PNaClABISimplifyAddPreOptPasses(PassManager &PM) {
+  // LowerInvoke prevents use of C++ exception handling, which is not
+  // yet supported in the PNaCl ABI.
+  PM.add(createLowerInvokePass());
+  // Remove landingpad blocks made unreachable by LowerInvoke.
+  PM.add(createCFGSimplificationPass());
+
+  PM.add(createExpandVarArgsPass());
+  PM.add(createExpandCtorsPass());
+  PM.add(createResolveAliasesPass());
+  PM.add(createExpandTlsPass());
+  // GlobalCleanup needs to run after ExpandTls because
+  // __tls_template_start etc. are extern_weak before expansion
+  PM.add(createGlobalCleanupPass());
+  // Strip dead prototytes to appease the intrinsic ABI checks
+  // (ExpandVarArgs leaves around var-arg intrinsics).
+  PM.add(createStripDeadPrototypesPass());
+}
+
+void llvm::PNaClABISimplifyAddPostOptPasses(PassManager &PM) {
+  // We place ExpandByVal after optimization passes because some byval
+  // arguments can be expanded away by the ArgPromotion pass.  Leaving
+  // in "byval" during optimization also allows some dead stores to be
+  // eliminated, because "byval" is a stronger constraint than what
+  // ExpandByVal expands it to.
+  PM.add(createExpandByValPass());
+
+  // We place StripMetadata after optimization passes because
+  // optimizations depend on the metadata.
+  PM.add(createStripMetadataPass());
+
+  // FlattenGlobals introduces ConstantExpr bitcasts of globals which
+  // are expanded out later.
+  PM.add(createFlattenGlobalsPass());
+
+  // We should not place arbitrary passes after ExpandConstantExpr
+  // because they might reintroduce ConstantExprs.  However,
+  // ExpandGetElementPtr must follow ExpandConstantExpr to expand the
+  // getelementptr instructions it creates.
+  PM.add(createExpandConstantExprPass());
+  PM.add(createExpandGetElementPtrPass());
+}