forked from rust-lang/llvm-project
-
Notifications
You must be signed in to change notification settings - Fork 0
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Merge pull request rust-lang#105 from ptersilie/nomoreentryblockcalls
Add pass disallowing calls in entry blocks.
- Loading branch information
Showing
6 changed files
with
169 additions
and
8 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,10 @@ | ||
| #ifndef LLVM_TRANSFORMS_YK_NOCALLSINENTRYBLOCKS_H | ||
| #define LLVM_TRANSFORMS_YK_NOCALLSINENTRYBLOCKS_H | ||
|
|
||
| #include "llvm/Pass.h" | ||
|
|
||
| namespace llvm { | ||
| ModulePass *createYkNoCallsInEntryBlocksPass(); | ||
| } // namespace llvm | ||
|
|
||
| #endif |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| // NoCallsInEntryBlocks.cpp - Ensure there are no calls in the first block. | ||
| // | ||
| // This pass splits up the entry block so that there are no calls inside it | ||
| // (one exception being the malloc call inserted by the shadowstack pass which | ||
| // will be applied later). This allows us to detect call backs from external | ||
| // functions more easily, which in turn simplifies our JITModBuilder | ||
| // implementation and fixes the soundness issue that existed in the old | ||
| // StackAdjust approach. | ||
| // | ||
| // As a simplified example, imagine this function: | ||
| // | ||
| // void foo(int argc) { | ||
| // if (argc == 0) { | ||
| // extfunc(foo) | ||
| // } | ||
| // } | ||
| // | ||
| // where `extfunc` may or may not call back to `foo`. Previously, this might | ||
| // result in a trace like | ||
| // | ||
| // foo.0 | ||
| // extfunc | ||
| // foo.0 | ||
| // ... | ||
| // | ||
| // Upon seeing the second `foo.0` we are unable to determine whether we are | ||
| // observing a callback to `foo` or are returning from `extfunc` which hasn't | ||
| // called foo. When running this pass we force `extfunc` not to be in the entry | ||
| // block, resulting in a trace like | ||
| // | ||
| // foo.0 | ||
| // foo.1 | ||
| // extfunc | ||
| // foo.1 | ||
| // ... | ||
| // | ||
| // Here it is clear that `extfunc` has not called `foo` as we are seeing block | ||
| // `foo.1` next. If `extfunc` had called `foo`, the next block would be | ||
| // `foo.0`. | ||
|
|
||
| #include "llvm/Transforms/Yk/NoCallsInEntryBlocks.h" | ||
| #include "llvm/IR/BasicBlock.h" | ||
| #include "llvm/IR/Function.h" | ||
| #include "llvm/IR/IRBuilder.h" | ||
| #include "llvm/IR/Instructions.h" | ||
| #include "llvm/IR/Module.h" | ||
| #include "llvm/IR/Verifier.h" | ||
| #include "llvm/InitializePasses.h" | ||
| #include "llvm/Pass.h" | ||
| #include "llvm/Transforms/Yk/LivenessAnalysis.h" | ||
|
|
||
| #define DEBUG_TYPE "yk-no-more-entryblock-calls" | ||
|
|
||
| using namespace llvm; | ||
|
|
||
| namespace llvm { | ||
| void initializeYkNoCallsInEntryBlocksPass(PassRegistry &); | ||
| } // namespace llvm | ||
|
|
||
| namespace { | ||
|
|
||
| class YkNoCallsInEntryBlocks : public ModulePass { | ||
| public: | ||
| static char ID; | ||
| YkNoCallsInEntryBlocks() : ModulePass(ID) { | ||
| initializeYkNoCallsInEntryBlocksPass(*PassRegistry::getPassRegistry()); | ||
| } | ||
|
|
||
| bool runOnModule(Module &M) override { | ||
| LLVMContext &Context = M.getContext(); | ||
|
|
||
| // split block at first function call | ||
| std::set<Instruction *> Calls; | ||
| for (Function &F : M) { | ||
| if (F.empty()) // skip declarations. | ||
| continue; | ||
| BasicBlock &BB = F.getEntryBlock(); | ||
| auto CurrFuncName = F.getName(); | ||
| for (Instruction &I : BB) { | ||
| if (isa<CallInst>(I)) { | ||
| Function *F = cast<CallInst>(I).getCalledFunction(); | ||
| BB.splitBasicBlock(&I); | ||
| break; | ||
| } | ||
| } | ||
| } | ||
|
|
||
| #ifndef NDEBUG | ||
| // Our pass runs after LLVM normally does its verify pass. In debug builds | ||
| // we run it again to check that our pass is generating valid IR. | ||
| if (verifyModule(M, &errs())) { | ||
| Context.emitError("Stackmap insertion pass generated invalid IR!"); | ||
| return false; | ||
| } | ||
| #endif | ||
| return true; | ||
| } | ||
| }; | ||
| } // namespace | ||
|
|
||
| char YkNoCallsInEntryBlocks::ID = 0; | ||
| INITIALIZE_PASS(YkNoCallsInEntryBlocks, DEBUG_TYPE, "no more entry block calls", | ||
| false, false) | ||
|
|
||
| ModulePass *llvm::createYkNoCallsInEntryBlocksPass() { | ||
| return new YkNoCallsInEntryBlocks(); | ||
| } |