mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-09-30 19:55:11 +00:00
afe3498413
This is a refactoring to restructure the single user of performCustomLowering as a specific lowering pass and remove the custom lowering hook entirely. Before this change, the LowerIntrinsics pass (note to self: rename!) was essentially acting as a pass manager, but without being structured in terms of passes. Instead, it proxied calls to a set of GCStrategies internally. This adds a lot of conceptual complexity (i.e. GCStrategies are stateful!) for very little benefit. Since there's been interest in keeping the ShadowStackGC working, I extracting it's custom lowering pass into a dedicated pass and just added that to the pass order. It will only run for functions which opt-in to that gc. I wasn't able to find an easy way to preserve the runtime registration of custom lowering functionality. Given that no user of this exists that I'm aware of, I made the choice to just remove that. If someone really cares, we can look at restoring it via dynamic pass registration in the future. Note that despite the large diff, none of the lowering code actual changes. I added the framing needed to make it a pass and rename the class, but that's it. Differential Revision: http://reviews.llvm.org/D7218 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227351 91177308-0d34-0410-b5e6-96231b3b80d8
56 lines
1.7 KiB
C++
56 lines
1.7 KiB
C++
//===-- ShadowStackGC.cpp - GC support for uncooperative targets ----------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements lowering for the llvm.gc* intrinsics for targets that do
|
|
// not natively support them (which includes the C backend). Note that the code
|
|
// generated is not quite as efficient as algorithms which generate stack maps
|
|
// to identify roots.
|
|
//
|
|
// This pass implements the code transformation described in this paper:
|
|
// "Accurate Garbage Collection in an Uncooperative Environment"
|
|
// Fergus Henderson, ISMM, 2002
|
|
//
|
|
// In runtime/GC/SemiSpace.cpp is a prototype runtime which is compatible with
|
|
// ShadowStackGC.
|
|
//
|
|
// In order to support this particular transformation, all stack roots are
|
|
// coallocated in the stack. This allows a fully target-independent stack map
|
|
// while introducing only minor runtime overhead.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/CodeGen/GCs.h"
|
|
#include "llvm/CodeGen/GCStrategy.h"
|
|
#include "llvm/ADT/StringExtras.h"
|
|
#include "llvm/IR/CallSite.h"
|
|
#include "llvm/IR/IRBuilder.h"
|
|
#include "llvm/IR/IntrinsicInst.h"
|
|
#include "llvm/IR/Module.h"
|
|
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "shadowstackgc"
|
|
|
|
namespace {
|
|
class ShadowStackGC : public GCStrategy {
|
|
public:
|
|
ShadowStackGC();
|
|
};
|
|
}
|
|
|
|
static GCRegistry::Add<ShadowStackGC>
|
|
X("shadow-stack", "Very portable GC for uncooperative code generators");
|
|
|
|
void llvm::linkShadowStackGC() {}
|
|
|
|
ShadowStackGC::ShadowStackGC() {
|
|
InitRoots = true;
|
|
CustomRoots = true;
|
|
}
|