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CodeGen: block capture shouldn't ICE 

When a lambda capture captures a __block in the same statement, the compiler asserts out because isCapturedBy assumes that an Expr can only be a BlockExpr, StmtExpr, or if it's a Stmt then all the statement's children are expressions. That's wrong, we need to visit all sub-statements even if they're not expressions to see if they also capture.

Fix this issue by pulling out the isCapturedBy logic to use RecursiveASTVisitor.

<rdar://problem/39926584>

llvm-svn: 332801
This commit is contained in:
JF Bastien 2018-05-19 04:21:26 +00:00
parent fcd50538c2
commit 6b23972f07
2 changed files with 39 additions and 13 deletions
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39
clang/lib/CodeGen/CGDecl.cpp
View File

@ -1244,17 +1244,30 @@ CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
return emission;
}
static bool isCapturedBy(const VarDecl &, const Expr *);
/// Determines whether the given __block variable is potentially
/// captured by the given statement.
static bool isCapturedBy(const VarDecl &Var, const Stmt *S) {
if (const Expr *E = dyn_cast<Expr>(S))
return isCapturedBy(Var, E);
for (const Stmt *SubStmt : S->children())
if (isCapturedBy(Var, SubStmt))
return true;
return false;
}
/// Determines whether the given __block variable is potentially
/// captured by the given expression.
static bool isCapturedBy(const VarDecl &var, const Expr *e) {
static bool isCapturedBy(const VarDecl &Var, const Expr *E) {
// Skip the most common kinds of expressions that make
// hierarchy-walking expensive.
e = e->IgnoreParenCasts();
E = E->IgnoreParenCasts();
if (const BlockExpr *be = dyn_cast<BlockExpr>(e)) {
const BlockDecl *block = be->getBlockDecl();
for (const auto &I : block->captures()) {
if (I.getVariable() == &var)
if (const BlockExpr *BE = dyn_cast<BlockExpr>(E)) {
const BlockDecl *Block = BE->getBlockDecl();
for (const auto &I : Block->captures()) {
if (I.getVariable() == &Var)
return true;
}
@ -1262,19 +1275,19 @@ static bool isCapturedBy(const VarDecl &var, const Expr *e) {
return false;
}
if (const StmtExpr *SE = dyn_cast<StmtExpr>(e)) {
if (const StmtExpr *SE = dyn_cast<StmtExpr>(E)) {
const CompoundStmt *CS = SE->getSubStmt();
for (const auto *BI : CS->body())
if (const auto *E = dyn_cast<Expr>(BI)) {
if (isCapturedBy(var, E))
return true;
if (const auto *BIE = dyn_cast<Expr>(BI)) {
if (isCapturedBy(Var, BIE))
return true;
}
else if (const auto *DS = dyn_cast<DeclStmt>(BI)) {
// special case declarations
for (const auto *I : DS->decls()) {
if (const auto *VD = dyn_cast<VarDecl>((I))) {
const Expr *Init = VD->getInit();
if (Init && isCapturedBy(var, Init))
if (Init && isCapturedBy(Var, Init))
return true;
}
}
@ -1286,8 +1299,8 @@ static bool isCapturedBy(const VarDecl &var, const Expr *e) {
return false;
}
for (const Stmt *SubStmt : e->children())
if (isCapturedBy(var, cast<Expr>(SubStmt)))
for (const Stmt *SubStmt : E->children())
if (isCapturedBy(Var, SubStmt))
return true;
return false;

13
clang/test/CodeGenCXX/block-capture.cpp Normal file
View File

@ -0,0 +1,13 @@
// RUN: %clang_cc1 -x c++ -std=c++11 -fblocks -emit-llvm %s -o - | FileCheck %s
// CHECK: %struct.__block_byref_baz = type { i8*, %struct.__block_byref_baz*, i32, i32, i32 }
// CHECK: [[baz:%[0-9a-z_]*]] = alloca %struct.__block_byref_baz
// CHECK: [[bazref:%[0-9a-z_\.]*]] = getelementptr inbounds %struct.__block_byref_baz, %struct.__block_byref_baz* [[baz]], i32 0, i32 1
// CHECK: store %struct.__block_byref_baz* [[baz]], %struct.__block_byref_baz** [[bazref]]
// CHECK: [[disposable:%[0-9a-z_]*]] = bitcast %struct.__block_byref_baz* [[baz]] to i8*
// CHECK: call void @_Block_object_dispose(i8* [[disposable]]
int main() {
__block int baz = [&]() { return 0; }();
return 0;
}