[cfe-commits] r71198 - /cfe/trunk/lib/CodeGen/CGObjCGNU.cpp
Chris Lattner
sabre at nondot.org
Thu May 7 17:11:50 PDT 2009
Author: lattner
Date: Thu May 7 19:11:50 2009
New Revision: 71198
URL: http://llvm.org/viewvc/llvm-project?rev=71198&view=rev
Log:
initial support for ObjC exceptions with the GNU runtime:
"This patch is a first pass at adding support for exceptions for the GNU runtime. There are a few limitations at present:
- @synchronized() is not yet supported at all. gcc currently emits calls to runtime library functions that don't exist for this directive.
- Only id @catch statements are currently working. This is enough for NS_DURING and friends, but I need to spend more time reading the output from gcc -S to work out how it finds the class pointer to make arbitrary class type catch statements work.
- I've tested it with a few common cases[1] and the clang test suite (which doesn't test exceptions for the GNU runtime, but shows I haven't broken anything else), but there are probably a lot of cases I've missed."
Patch by David Chisnall!
Modified:
cfe/trunk/lib/CodeGen/CGObjCGNU.cpp
Modified: cfe/trunk/lib/CodeGen/CGObjCGNU.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGObjCGNU.cpp?rev=71198&r1=71197&r2=71198&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGObjCGNU.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGObjCGNU.cpp Thu May 7 19:11:50 2009
@@ -17,16 +17,20 @@
#include "CGObjCRuntime.h"
#include "CodeGenModule.h"
#include "CodeGenFunction.h"
+
#include "clang/AST/ASTContext.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtObjC.h"
+
+#include "llvm/Intrinsics.h"
#include "llvm/Module.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Target/TargetData.h"
+
#include <map>
@@ -1109,12 +1113,235 @@
void CGObjCGNU::EmitTryOrSynchronizedStmt(CodeGen::CodeGenFunction &CGF,
const Stmt &S) {
- CGF.ErrorUnsupported(&S, "@try/@synchronized statement");
+ // Pointer to the personality function
+ llvm::Constant *Personality =
+ CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::Int32Ty,
+ std::vector<const llvm::Type*>(), true),
+ "__gnu_objc_personality_v0");
+ Personality = llvm::ConstantExpr::getBitCast(Personality, PtrTy);
+ std::vector<const llvm::Type*> Params;
+ Params.push_back(PtrTy);
+ llvm::Value *RethrowFn =
+ CGM.CreateRuntimeFunction(llvm::FunctionType::get(llvm::Type::VoidTy,
+ Params, false), "_Unwind_Resume_or_Rethrow");
+
+ bool isTry = isa<ObjCAtTryStmt>(S);
+ llvm::BasicBlock *TryBlock = CGF.createBasicBlock("try");
+ llvm::BasicBlock *PrevLandingPad = CGF.getInvokeDest();
+ llvm::BasicBlock *TryHandler = CGF.createBasicBlock("try.handler");
+ llvm::BasicBlock *FinallyBlock = CGF.createBasicBlock("finally");
+ llvm::BasicBlock *FinallyRethrow = CGF.createBasicBlock("finally.throw");
+ llvm::BasicBlock *FinallyEnd = CGF.createBasicBlock("finally.end");
+
+ // GNU runtime does not currently support @synchronized()
+ if (!isTry) {
+ CGF.ErrorUnsupported(&S, "@synchronized statement");
+ }
+
+ // Push an EH context entry, used for handling rethrows and jumps
+ // through finally.
+ CGF.PushCleanupBlock(FinallyBlock);
+
+ // Emit the statements in the @try {} block
+ CGF.setInvokeDest(TryHandler);
+
+ CGF.EmitBlock(TryBlock);
+ CGF.EmitStmt(isTry ? cast<ObjCAtTryStmt>(S).getTryBody()
+ : cast<ObjCAtSynchronizedStmt>(S).getSynchBody());
+
+ // Jump to @finally if there is no exception
+ CGF.EmitBranchThroughCleanup(FinallyEnd);
+
+ // Emit the handlers
+ CGF.EmitBlock(TryHandler);
+
+ llvm::Value *llvm_eh_exception =
+ CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_exception);
+ llvm::Value *llvm_eh_selector_i64 =
+ CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_selector_i32);
+ llvm::Value *llvm_eh_typeid_for_i64 =
+ CGF.CGM.getIntrinsic(llvm::Intrinsic::eh_typeid_for_i32);
+
+ // Exception object
+ llvm::Value *Exc = CGF.Builder.CreateCall(llvm_eh_exception, "exc");
+ llvm::Value *RethrowPtr = CGF.CreateTempAlloca(Exc->getType(), "_rethrow");
+
+ llvm::SmallVector<llvm::Value*, 8> ESelArgs;
+ llvm::SmallVector<std::pair<const ParmVarDecl*, const Stmt*>, 8> Handlers;
+
+ ESelArgs.push_back(Exc);
+ ESelArgs.push_back(Personality);
+
+ bool HasCatchAll = false;
+ // Only @try blocks are allowed @catch blocks, but both can have @finally
+ if (isTry) {
+ if (const ObjCAtCatchStmt* CatchStmt =
+ cast<ObjCAtTryStmt>(S).getCatchStmts()) {
+
+ for (; CatchStmt; CatchStmt = CatchStmt->getNextCatchStmt()) {
+ const ParmVarDecl *CatchDecl = CatchStmt->getCatchParamDecl();
+ Handlers.push_back(std::make_pair(CatchDecl, CatchStmt->getCatchBody()));
+
+ // @catch() and @catch(id) both catch any ObjC exception
+ if (!CatchDecl || CGF.getContext().isObjCIdType(CatchDecl->getType())
+ || CatchDecl->getType()->isObjCQualifiedIdType()) {
+ // Use i8* null here to signal this is a catch all, not a cleanup.
+ ESelArgs.push_back(NULLPtr);
+ HasCatchAll = true;
+ // No further catches after this one will ever by reached
+ break;
+ }
+
+ // All other types should be Objective-C interface pointer types.
+ const PointerType *PT = CatchDecl->getType()->getAsPointerType();
+ assert(PT && "Invalid @catch type.");
+ const ObjCInterfaceType *IT =
+ PT->getPointeeType()->getAsObjCInterfaceType();
+ assert(IT && "Invalid @catch type.");
+ CGF.ErrorUnsupported(&S, "@catch block with non-id argument statement");
+ // FIXME: This should be the Class for the corresponding interface
+ llvm::Value *EHType = NULLPtr;
+ ESelArgs.push_back(EHType);
+ }
+ }
+ }
+
+ // We use a cleanup unless there was already a catch all.
+ if (!HasCatchAll) {
+ ESelArgs.push_back(llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
+ Handlers.push_back(std::make_pair((const ParmVarDecl*) 0, (const Stmt*) 0));
+ }
+
+ // Find which handler was matched.
+ llvm::Value *ESelector = CGF.Builder.CreateCall(llvm_eh_selector_i64,
+ ESelArgs.begin(), ESelArgs.end(), "selector");
+
+ for (unsigned i = 0, e = Handlers.size(); i != e; ++i) {
+ const ParmVarDecl *CatchParam = Handlers[i].first;
+ const Stmt *CatchBody = Handlers[i].second;
+
+ llvm::BasicBlock *Next = 0;
+
+ // The last handler always matches.
+ if (i + 1 != e) {
+ assert(CatchParam && "Only last handler can be a catch all.");
+
+ // Test whether this block matches the type for the selector and branch
+ // to Match if it does, or to the next BB if it doesn't.
+ llvm::BasicBlock *Match = CGF.createBasicBlock("match");
+ Next = CGF.createBasicBlock("catch.next");
+ llvm::Value *Id = CGF.Builder.CreateCall(llvm_eh_typeid_for_i64,
+ CGF.Builder.CreateBitCast(ESelArgs[i+2], PtrTy));
+ CGF.Builder.CreateCondBr(CGF.Builder.CreateICmpEQ(ESelector, Id), Match,
+ Next);
+
+ CGF.EmitBlock(Match);
+ }
+
+ if (CatchBody) {
+ //FIXME: Do we need to reset the invoke destination here? Exceptions in
+ //@catch {} blocks should unwind higher up.
+
+ //FIXME: This may not be right. The exception object is returned in
+ //__builtin_eh_return_data_regno(0), but I am not sure how to get at
+ //this in LLVM
+ llvm::Value *ExcObject = CGF.Builder.CreateBitCast(Exc,
+ CGF.ConvertType(CatchParam->getType()));
+
+ // Bind the catch parameter if it exists.
+ if (CatchParam) {
+ // CatchParam is a ParmVarDecl because of the grammar
+ // construction used to handle this, but for codegen purposes
+ // we treat this as a local decl.
+ CGF.EmitLocalBlockVarDecl(*CatchParam);
+ CGF.Builder.CreateStore(ExcObject, CGF.GetAddrOfLocalVar(CatchParam));
+ }
+
+ CGF.ObjCEHValueStack.push_back(ExcObject);
+ CGF.EmitStmt(CatchBody);
+ CGF.ObjCEHValueStack.pop_back();
+
+ CGF.EmitBranchThroughCleanup(FinallyEnd);
+
+ if (Next)
+ CGF.EmitBlock(Next);
+ } else {
+ assert(!Next && "catchup should be last handler.");
+
+ CGF.Builder.CreateStore(Exc, RethrowPtr);
+ CGF.EmitBranchThroughCleanup(FinallyRethrow);
+ }
+ }
+ CodeGenFunction::CleanupBlockInfo Info = CGF.PopCleanupBlock();
+
+ CGF.setInvokeDest(PrevLandingPad);
+
+ CGF.EmitBlock(FinallyBlock);
+
+ if (isTry) {
+ if (const ObjCAtFinallyStmt* FinallyStmt =
+ cast<ObjCAtTryStmt>(S).getFinallyStmt())
+ CGF.EmitStmt(FinallyStmt->getFinallyBody());
+ } else {
+ // TODO: Emit 'objc_sync_exit(expr)' as finally's sole statement for
+ // @synchronized.
+ }
+
+ if (Info.SwitchBlock)
+ CGF.EmitBlock(Info.SwitchBlock);
+ if (Info.EndBlock)
+ CGF.EmitBlock(Info.EndBlock);
+
+ // Branch around the rethrow code.
+ CGF.EmitBranch(FinallyEnd);
+
+ CGF.EmitBlock(FinallyRethrow);
+ CGF.Builder.CreateCall(RethrowFn, CGF.Builder.CreateLoad(RethrowPtr));
+ CGF.Builder.CreateUnreachable();
+
+ CGF.EmitBlock(FinallyEnd);
+
}
void CGObjCGNU::EmitThrowStmt(CodeGen::CodeGenFunction &CGF,
const ObjCAtThrowStmt &S) {
- CGF.ErrorUnsupported(&S, "@throw statement");
+ llvm::Value *ExceptionAsObject;
+
+ std::vector<const llvm::Type*> Args(1, IdTy);
+ llvm::FunctionType *FTy =
+ llvm::FunctionType::get(llvm::Type::VoidTy, Args, false);
+ llvm::Value *ThrowFn =
+ CGM.CreateRuntimeFunction(FTy, "objc_exception_throw");
+
+ if (const Expr *ThrowExpr = S.getThrowExpr()) {
+ llvm::Value *Exception = CGF.EmitScalarExpr(ThrowExpr);
+ ExceptionAsObject =
+ CGF.Builder.CreateBitCast(Exception, IdTy, "tmp");
+ } else {
+ assert((!CGF.ObjCEHValueStack.empty() && CGF.ObjCEHValueStack.back()) &&
+ "Unexpected rethrow outside @catch block.");
+ ExceptionAsObject = CGF.ObjCEHValueStack.back();
+ }
+
+ // Note: This may have to be an invoke, if we want to support constructs like:
+ // @try {
+ // @throw(obj);
+ // }
+ // @catch(id) ...
+ //
+ // This is effectively turning @throw into an incredibly-expensive goto, but
+ // it may happen as a result of inlining followed by missed optimizations, or
+ // as a result of stupidity.
+ llvm::BasicBlock *UnwindBB = CGF.getInvokeDest();
+ if (!UnwindBB) {
+ CGF.Builder.CreateCall(ThrowFn, ExceptionAsObject);
+ CGF.Builder.CreateUnreachable();
+ } else {
+ CGF.Builder.CreateInvoke(ThrowFn, UnwindBB, UnwindBB, &ExceptionAsObject,
+ &ExceptionAsObject+1);
+ }
+ // Clear the insertion point to indicate we are in unreachable code.
+ CGF.Builder.ClearInsertionPoint();
}
llvm::Value * CGObjCGNU::EmitObjCWeakRead(CodeGen::CodeGenFunction &CGF,
More information about the cfe-commits
mailing list