From 784d4a455b42272c27a28e152d4c9f9e51293aa4 Mon Sep 17 00:00:00 2001 From: David Majnemer Date: Mon, 1 Feb 2016 03:29:38 +0000 Subject: [PATCH] Revert r258580 and r258581. Those commits created an artificial edge from a cleanup to a synthesized catchswitch in order to get the MSVC personality routine to execute cleanups which don't cleanupret and are not wrapped by a catchswitch. This worked well enough but is not a complete solution in situations where there the cleanup infinite loops. However, the real deal breaker behind this approach comes about from a degenerate case where the cleanup is post-dominated by unreachable *and* throws an exception. This ends poorly because the catchswitch will inadvertently catch the exception. Because of this we should go back to our previous behavior of not executing certain cleanups (identical behavior with the Itanium ABI implementation in clang, GCC and ICC). N.B. I think this could be salvaged by making the catchpad rethrow the exception and properly transforming throwing calls in the cleanup into invokes. llvm-svn: 259338 --- llvm/lib/CodeGen/WinEHPrepare.cpp | 113 ------------------ .../WinEH/wineh-cleanuppad-nounwind.ll | 95 --------------- llvm/test/CodeGen/WinEH/wineh-cloning.ll | 4 +- llvm/test/CodeGen/WinEH/wineh-demotion.ll | 3 +- llvm/test/CodeGen/WinEH/wineh-no-demotion.ll | 2 +- 5 files changed, 4 insertions(+), 213 deletions(-) delete mode 100644 llvm/test/CodeGen/WinEH/wineh-cleanuppad-nounwind.ll diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp index 12733acf3b80..281fe9342926 100644 --- a/llvm/lib/CodeGen/WinEHPrepare.cpp +++ b/llvm/lib/CodeGen/WinEHPrepare.cpp @@ -81,7 +81,6 @@ private: void cloneCommonBlocks(Function &F); void removeImplausibleInstructions(Function &F); void cleanupPreparedFunclets(Function &F); - void fixupNoReturnCleanupPads(Function &F); void verifyPreparedFunclets(Function &F); // All fields are reset by runOnFunction. @@ -657,7 +656,6 @@ void llvm::calculateClrEHStateNumbers(const Function *Fn, void WinEHPrepare::colorFunclets(Function &F) { BlockColors = colorEHFunclets(F); - FuncletBlocks.clear(); // Invert the map from BB to colors to color to BBs. for (BasicBlock &BB : F) { @@ -1003,115 +1001,6 @@ void WinEHPrepare::cleanupPreparedFunclets(Function &F) { removeUnreachableBlocks(F); } -// Cleanuppads which are postdominated by unreachable will not unwind to any -// catchswitches, making them dead. This is problematic if the original source -// had a catch clause which could legitimately catch the exception, causing the -// cleanup to run. -// -// This is only a problem for C++ where down-stream catches cause cleanups to -// run. -void WinEHPrepare::fixupNoReturnCleanupPads(Function &F) { - // We only need to do this for C++ personality routines, - // skip this work for all others. - if (Personality != EHPersonality::MSVC_CXX) - return; - - // Do a quick sanity check on the color map before we throw it away so as to - // avoid hiding latent bugs. - DEBUG(verifyPreparedFunclets(F)); - // Re-color the funclets because cleanupPreparedFunclets might have - // invalidated FuncletBlocks. - colorFunclets(F); - - // We create a unique catchswitch for each parent it will be nested within. - SmallDenseMap NewCatchSwitches; - // Create a new catchswitch+catchpad where the catchpad is post-dominated by - // unreachable. - auto GetOrCreateCatchSwitch = [&](Value *ParentPad) { - auto &CatchSwitch = NewCatchSwitches[ParentPad]; - if (CatchSwitch) - return CatchSwitch; - - auto *ParentBB = isa(ParentPad) - ? &F.getEntryBlock() - : cast(ParentPad)->getParent(); - - StringRef NameSuffix = ParentBB->getName(); - - BasicBlock *CatchSwitchBB = BasicBlock::Create( - F.getContext(), Twine("catchswitchbb.for.", NameSuffix)); - CatchSwitchBB->insertInto(&F, ParentBB->getNextNode()); - CatchSwitch = CatchSwitchInst::Create(ParentPad, /*UnwindDest=*/nullptr, - /*NumHandlers=*/1, - Twine("catchswitch.for.", NameSuffix), - CatchSwitchBB); - - BasicBlock *CatchPadBB = BasicBlock::Create( - F.getContext(), Twine("catchpadbb.for.", NameSuffix)); - CatchPadBB->insertInto(&F, CatchSwitchBB->getNextNode()); - Value *CatchPadArgs[] = { - Constant::getNullValue(Type::getInt8PtrTy(F.getContext())), - ConstantInt::get(Type::getInt32Ty(F.getContext()), 64), - Constant::getNullValue(Type::getInt8PtrTy(F.getContext())), - }; - CatchPadInst::Create(CatchSwitch, CatchPadArgs, - Twine("catchpad.for.", NameSuffix), CatchPadBB); - new UnreachableInst(F.getContext(), CatchPadBB); - - CatchSwitch->addHandler(CatchPadBB); - - return CatchSwitch; - }; - - // Look for all basic blocks which are within cleanups which are postdominated - // by unreachable. - for (auto &Funclets : FuncletBlocks) { - BasicBlock *FuncletPadBB = Funclets.first; - auto *CleanupPad = dyn_cast(FuncletPadBB->getFirstNonPHI()); - // Skip over any non-cleanup funclets. - if (!CleanupPad) - continue; - // Skip over any cleanups have unwind targets, they do not need this. - if (any_of(CleanupPad->users(), - [](const User *U) { return isa(U); })) - continue; - // Walk the blocks within the cleanup which end in 'unreachable'. - // We will replace the unreachable instruction with a cleanupret; - // this cleanupret will unwind to a catchswitch with a lone catch-all - // catchpad. - std::vector &BlocksInFunclet = Funclets.second; - for (BasicBlock *BB : BlocksInFunclet) { - auto *UI = dyn_cast(BB->getTerminator()); - if (!UI) - continue; - // Remove the unreachable instruction. - UI->eraseFromParent(); - - // Add our new cleanupret. - auto *ParentPad = CleanupPad->getParentPad(); - CatchSwitchInst *CatchSwitch = GetOrCreateCatchSwitch(ParentPad); - CleanupReturnInst::Create(CleanupPad, CatchSwitch->getParent(), BB); - } - } - - // Update BlockColors and FuncletBlocks to maintain WinEHPrepare's - // invariants. - for (auto CatchSwitchKV : NewCatchSwitches) { - CatchSwitchInst *CatchSwitch = CatchSwitchKV.second; - BasicBlock *CatchSwitchBB = CatchSwitch->getParent(); - - assert(CatchSwitch->getNumSuccessors() == 1); - BasicBlock *CatchPadBB = CatchSwitch->getSuccessor(0); - assert(isa(CatchPadBB->getFirstNonPHI())); - - BlockColors.insert({CatchSwitchBB, ColorVector(CatchSwitchBB)}); - FuncletBlocks[CatchSwitchBB] = {CatchSwitchBB}; - - BlockColors.insert({CatchPadBB, ColorVector(CatchPadBB)}); - FuncletBlocks[CatchPadBB] = {CatchPadBB}; - } -} - void WinEHPrepare::verifyPreparedFunclets(Function &F) { for (BasicBlock &BB : F) { size_t NumColors = BlockColors[&BB].size(); @@ -1147,8 +1036,6 @@ bool WinEHPrepare::prepareExplicitEH(Function &F) { cleanupPreparedFunclets(F); } - fixupNoReturnCleanupPads(F); - DEBUG(verifyPreparedFunclets(F)); // Recolor the CFG to verify that all is well. DEBUG(colorFunclets(F)); diff --git a/llvm/test/CodeGen/WinEH/wineh-cleanuppad-nounwind.ll b/llvm/test/CodeGen/WinEH/wineh-cleanuppad-nounwind.ll deleted file mode 100644 index ff6b70ab190a..000000000000 --- a/llvm/test/CodeGen/WinEH/wineh-cleanuppad-nounwind.ll +++ /dev/null @@ -1,95 +0,0 @@ -; RUN: opt -S -winehprepare < %s | FileCheck %s -target triple = "x86_64-pc-windows-msvc" - -; CHECK-LABEL: @test1( -define void @test1(i1 %b) personality i32 (...)* @__CxxFrameHandler3 { -entry: - invoke void @f() - to label %try.cont unwind label %cleanup.bb - -; CHECK: entry: - -; CHECK: [[catchswitch_entry:.*]]: -; CHECK-NEXT: %[[cs0:.*]] = catchswitch within none [label %[[catchpad:.*]]] unwind to caller -; CHECK: [[catchpad]]: -; CHECK-NEXT: %[[cp0:.*]] = catchpad within %[[cs0]] [i8* null, i32 64, i8* null] -; CHECK-NEXT: unreachable - -try.cont: - invoke void @f() - to label %exit unwind label %catchswitch.bb - -cleanup.bb: - %cleanup = cleanuppad within none [] - br i1 %b, label %left, label %right - -left: - call void @exit(i32 0) [ "funclet"(token %cleanup) ] - unreachable - -right: - call void @exit(i32 1) [ "funclet"(token %cleanup) ] - unreachable - -catchswitch.bb: - %cs = catchswitch within none [label %catchpad.bb] unwind to caller - -; CHECK: catchpad.bb: -; CHECK-NEXT: %catch = catchpad within %cs [i8* null, i32 64, i8* null] - -; CHECK: [[catchswitch_catch:.*]]: -; CHECK-NEXT: %[[cs1:.*]] = catchswitch within %catch [label %[[catchpad_catch:.*]]] unwind to caller -; CHECK: [[catchpad_catch]]: -; CHECK-NEXT: %[[cp1:.*]] = catchpad within %[[cs1]] [i8* null, i32 64, i8* null] -; CHECK-NEXT: unreachable - -; CHECK: nested.cleanup.bb: -; CHECK-NEXT: %nested.cleanup = cleanuppad within %catch [] -; CHECK-NEXT: call void @exit(i32 2) [ "funclet"(token %nested.cleanup) ] -; CHECK-NEXT: cleanupret from %nested.cleanup unwind label %[[catchswitch_catch]] - -catchpad.bb: - %catch = catchpad within %cs [i8* null, i32 64, i8* null] - invoke void @f() [ "funclet"(token %catch) ] - to label %unreachable unwind label %nested.cleanup.bb - -nested.cleanup.bb: - %nested.cleanup = cleanuppad within %catch [] - call void @exit(i32 2) [ "funclet"(token %nested.cleanup) ] - unreachable - -unreachable: - unreachable - -exit: - unreachable -} - -; CHECK-LABEL: @test2( -define void @test2(i1 %B) personality i32 (...)* @__CxxFrameHandler3 { -entry: - invoke void @f() - to label %invoke.cont unwind label %ehcleanup - -invoke.cont: - unreachable - -ehcleanup: - %cp = cleanuppad within none [] - br i1 %B, label %ret, label %if.then - -if.then: - call void @exit(i32 1) [ "funclet"(token %cp) ] - unreachable - -ret: - cleanupret from %cp unwind to caller -} - -; CHECK: call void @exit(i32 1) [ "funclet"(token %cp) ] -; CHECK-NEXT: unreachable - -declare void @f() -declare void @exit(i32) nounwind noreturn - -declare i32 @__CxxFrameHandler3(...) diff --git a/llvm/test/CodeGen/WinEH/wineh-cloning.ll b/llvm/test/CodeGen/WinEH/wineh-cloning.ll index 355ffa8c3f6a..748c07df1730 100644 --- a/llvm/test/CodeGen/WinEH/wineh-cloning.ll +++ b/llvm/test/CodeGen/WinEH/wineh-cloning.ll @@ -44,7 +44,7 @@ noreturn: ; CHECK: call void @llvm.foo(i32 %x) -define void @test2() personality i32 (...)* @__C_specific_handler { +define void @test2() personality i32 (...)* @__CxxFrameHandler3 { entry: invoke void @f() to label %exit unwind label %cleanup @@ -71,7 +71,7 @@ exit: ; CHECK-NEXT: ret void -define void @test3() personality i32 (...)* @__C_specific_handler { +define void @test3() personality i32 (...)* @__CxxFrameHandler3 { entry: invoke void @f() to label %invoke.cont unwind label %catch.switch diff --git a/llvm/test/CodeGen/WinEH/wineh-demotion.ll b/llvm/test/CodeGen/WinEH/wineh-demotion.ll index 048466a26d16..411952d84bb6 100644 --- a/llvm/test/CodeGen/WinEH/wineh-demotion.ll +++ b/llvm/test/CodeGen/WinEH/wineh-demotion.ll @@ -1,7 +1,6 @@ ; RUN: opt -mtriple=x86_64-pc-windows-msvc -S -winehprepare < %s | FileCheck %s declare i32 @__CxxFrameHandler3(...) -declare i32 @__C_specific_handler(...) declare void @f() @@ -328,7 +327,7 @@ exit: } ; CHECK-LABEL: @test8( -define void @test8() personality i32 (...)* @__C_specific_handler { entry: +define void @test8() personality i32 (...)* @__CxxFrameHandler3 { entry: invoke void @f() to label %done unwind label %cleanup1 invoke void @f() diff --git a/llvm/test/CodeGen/WinEH/wineh-no-demotion.ll b/llvm/test/CodeGen/WinEH/wineh-no-demotion.ll index 277dd5c0e6a8..0901e27c301d 100644 --- a/llvm/test/CodeGen/WinEH/wineh-no-demotion.ll +++ b/llvm/test/CodeGen/WinEH/wineh-no-demotion.ll @@ -1,4 +1,4 @@ -; RUN: opt -mtriple=x86_64-pc-windows-msvc -S -winehprepare -disable-demotion -disable-cleanups < %s | FileCheck %s +; RUN: opt -mtriple=x86_x64-pc-windows-msvc -S -winehprepare -disable-demotion -disable-cleanups < %s | FileCheck %s declare i32 @__CxxFrameHandler3(...)