Reland "[SEH] Implement filter capturing in CodeGen"
The test should be fixed. It was failing in NDEBUG builds due to a
missing '*' character in a regex. In asserts builds, the pattern matched
a single digit value, which became a double digit value in NDEBUG
builds. Go figure.
This reverts commit r234261.
llvm-svn: 234447
diff --git a/clang/lib/CodeGen/CGException.cpp b/clang/lib/CodeGen/CGException.cpp
index f96c0a3..cc16053 100644
--- a/clang/lib/CodeGen/CGException.cpp
+++ b/clang/lib/CodeGen/CGException.cpp
@@ -19,8 +19,10 @@
#include "clang/AST/Mangle.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
+#include "clang/AST/StmtVisitor.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/IntrinsicInst.h"
using namespace clang;
using namespace CodeGen;
@@ -1339,6 +1341,110 @@
};
}
+namespace {
+/// Find all local variable captures in the statement.
+struct CaptureFinder : ConstStmtVisitor<CaptureFinder> {
+ CodeGenFunction &ParentCGF;
+ const VarDecl *ParentThis;
+ SmallVector<const VarDecl *, 4> Captures;
+ CaptureFinder(CodeGenFunction &ParentCGF, const VarDecl *ParentThis)
+ : ParentCGF(ParentCGF), ParentThis(ParentThis) {}
+
+ void Visit(const Stmt *S) {
+ // See if this is a capture, then recurse.
+ ConstStmtVisitor<CaptureFinder>::Visit(S);
+ for (const Stmt *Child : S->children())
+ Visit(Child);
+ }
+
+ void VisitDeclRefExpr(const DeclRefExpr *E) {
+ // If this is already a capture, just make sure we capture 'this'.
+ if (E->refersToEnclosingVariableOrCapture()) {
+ Captures.push_back(ParentThis);
+ return;
+ }
+
+ const auto *D = dyn_cast<VarDecl>(E->getDecl());
+ if (D && D->isLocalVarDeclOrParm() && D->hasLocalStorage())
+ Captures.push_back(D);
+ }
+
+ void VisitCXXThisExpr(const CXXThisExpr *E) {
+ Captures.push_back(ParentThis);
+ }
+};
+}
+
+void CodeGenFunction::EmitCapturedLocals(CodeGenFunction &ParentCGF,
+ const Stmt *OutlinedStmt,
+ llvm::Value *ParentFP) {
+ // Find all captures in the Stmt.
+ CaptureFinder Finder(ParentCGF, ParentCGF.CXXABIThisDecl);
+ Finder.Visit(OutlinedStmt);
+
+ // Typically there are no captures and we can exit early.
+ if (Finder.Captures.empty())
+ return;
+
+ // Prepare the first two arguments to llvm.framerecover.
+ llvm::Function *FrameRecoverFn = llvm::Intrinsic::getDeclaration(
+ &CGM.getModule(), llvm::Intrinsic::framerecover);
+ llvm::Constant *ParentI8Fn =
+ llvm::ConstantExpr::getBitCast(ParentCGF.CurFn, Int8PtrTy);
+
+ // Create llvm.framerecover calls for all captures.
+ for (const VarDecl *VD : Finder.Captures) {
+ if (isa<ImplicitParamDecl>(VD)) {
+ CGM.ErrorUnsupported(VD, "'this' captured by SEH");
+ CXXThisValue = llvm::UndefValue::get(ConvertTypeForMem(VD->getType()));
+ continue;
+ }
+ if (VD->getType()->isVariablyModifiedType()) {
+ CGM.ErrorUnsupported(VD, "VLA captured by SEH");
+ continue;
+ }
+
+ assert((isa<ImplicitParamDecl>(VD) || VD->isLocalVarDeclOrParm()) &&
+ "captured non-local variable");
+
+ llvm::Value *ParentVar = ParentCGF.LocalDeclMap[VD];
+ assert(ParentVar && "capture was not a local decl");
+ llvm::CallInst *RecoverCall = nullptr;
+ CGBuilderTy Builder(AllocaInsertPt);
+ if (auto *ParentAlloca = dyn_cast<llvm::AllocaInst>(ParentVar)) {
+ // Mark the variable escaped if nobody else referenced it and compute the
+ // frameescape index.
+ auto InsertPair =
+ ParentCGF.EscapedLocals.insert(std::make_pair(ParentAlloca, -1));
+ if (InsertPair.second)
+ InsertPair.first->second = ParentCGF.EscapedLocals.size() - 1;
+ int FrameEscapeIdx = InsertPair.first->second;
+ // call i8* @llvm.framerecover(i8* bitcast(@parentFn), i8* %fp, i32 N)
+ RecoverCall =
+ Builder.CreateCall3(FrameRecoverFn, ParentI8Fn, ParentFP,
+ llvm::ConstantInt::get(Int32Ty, FrameEscapeIdx));
+
+ } else {
+ // If the parent didn't have an alloca, we're doing some nested outlining.
+ // Just clone the existing framerecover call, but tweak the FP argument to
+ // use our FP value. All other arguments are constants.
+ auto *ParentRecover =
+ cast<llvm::IntrinsicInst>(ParentVar->stripPointerCasts());
+ assert(ParentRecover->getIntrinsicID() == llvm::Intrinsic::framerecover &&
+ "expected alloca or framerecover in parent LocalDeclMap");
+ RecoverCall = cast<llvm::CallInst>(ParentRecover->clone());
+ RecoverCall->setArgOperand(1, ParentFP);
+ RecoverCall->insertBefore(AllocaInsertPt);
+ }
+
+ // Bitcast the variable, rename it, and insert it in the local decl map.
+ llvm::Value *ChildVar =
+ Builder.CreateBitCast(RecoverCall, ParentVar->getType());
+ ChildVar->setName(ParentVar->getName());
+ LocalDeclMap[VD] = ChildVar;
+ }
+}
+
/// Create a stub filter function that will ultimately hold the code of the
/// filter expression. The EH preparation passes in LLVM will outline the code
/// from the main function body into this stub.
@@ -1392,15 +1498,9 @@
EmitSEHExceptionCodeSave();
- // Insert dummy allocas for every local variable in scope. We'll initialize
- // them and prune the unused ones after we find out which ones were
- // referenced.
- for (const auto &DeclPtrs : ParentCGF.LocalDeclMap) {
- const Decl *VD = DeclPtrs.first;
- llvm::Value *Ptr = DeclPtrs.second;
- auto *ValTy = cast<llvm::PointerType>(Ptr->getType())->getElementType();
- LocalDeclMap[VD] = CreateTempAlloca(ValTy, Ptr->getName() + ".filt");
- }
+ auto AI = Fn->arg_begin();
+ ++AI;
+ EmitCapturedLocals(ParentCGF, FilterExpr, &*AI);
// Emit the original filter expression, convert to i32, and return.
llvm::Value *R = EmitScalarExpr(FilterExpr);
@@ -1410,17 +1510,6 @@
FinishFunction(FilterExpr->getLocEnd());
- for (const auto &DeclPtrs : ParentCGF.LocalDeclMap) {
- const Decl *VD = DeclPtrs.first;
- auto *Alloca = cast<llvm::AllocaInst>(LocalDeclMap[VD]);
- if (Alloca->hasNUses(0)) {
- Alloca->eraseFromParent();
- continue;
- }
- ErrorUnsupported(FilterExpr,
- "SEH filter expression local variable capture");
- }
-
return Fn;
}