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[DebugInfo] Fix DWARF expressions for __block vars that are not on th… #2968

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Merged
merged 1 commit into from
May 17, 2021
Merged

[DebugInfo] Fix DWARF expressions for __block vars that are not on th… #2968

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4 changes: 3 additions & 1 deletion clang/lib/CodeGen/CGDebugInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4231,7 +4231,9 @@ llvm::DILocalVariable *CGDebugInfo::EmitDeclare(const VarDecl *VD,
auto *Scope = cast<llvm::DIScope>(LexicalBlockStack.back());
StringRef Name = VD->getName();
if (!Name.empty()) {
if (VD->hasAttr<BlocksAttr>()) {
// __block vars are stored on the heap if they are captured by a block that
// can escape the local scope.
if (VD->isEscapingByref()) {
// Here, we need an offset *into* the alloca.
CharUnits offset = CharUnits::fromQuantity(32);
Expr.push_back(llvm::dwarf::DW_OP_plus_uconst);
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54 changes: 50 additions & 4 deletions clang/test/CodeGen/debug-info-block-expr.c
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@@ -1,9 +1,55 @@
// RUN: %clang_cc1 -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -DDEAD_CODE -fblocks -debug-info-kind=limited -emit-llvm -o - %s | FileCheck %s

typedef void (^BlockTy)();
void escapeFunc(BlockTy);
typedef void (^BlockTy)();
void noEscapeFunc(__attribute__((noescape)) BlockTy);

// Verify that the desired DIExpression are generated for escaping (i.e, not
// 'noescape') blocks.
void test_escape_func() {
// CHECK-LABEL: void @test_escape_func
// CHECK: call void @llvm.dbg.declare({{.*}}metadata ![[ESCAPE_VAR:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}){{.*}})
__block int escape_var;
// Blocks in dead code branches still capture __block variables.
#ifdef DEAD_CODE
if (0)
#endif
escapeFunc(^{ (void)escape_var; });
}

// Verify that the desired DIExpression are generated for noescape blocks.
void test_noescape_func() {
// CHECK-LABEL: void @test_noescape_func
// CHECK: call void @llvm.dbg.declare({{.*}}metadata ![[NOESCAPE_VAR:[0-9]+]], metadata !DIExpression())
__block int noescape_var;
noEscapeFunc(^{ (void)noescape_var; });
}

// Verify that the desired DIExpression are generated for blocks.
void test_local_block() {
// CHECK-LABEL: void @test_local_block
// CHECK: call void @llvm.dbg.declare({{.*}}metadata ![[BLOCK_VAR:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}){{.*}})
__block int block_var;

void test() {
// CHECK: call void @llvm.dbg.declare({{.*}}!DIExpression(DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}){{.*}})
__block int i;
// CHECK-LABEL: @__test_local_block_block_invoke
// CHECK: call void @llvm.dbg.declare({{.*}}!DIExpression(DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}, DW_OP_deref, DW_OP_plus_uconst, {{[0-9]+}}){{.*}})
^ { i = 1; }();
^ { block_var = 1; }();
}

// Verify that the desired DIExpression are generated for __block vars not used
// in any block.
void test_unused() {
// CHECK-LABEL: void @test_unused
// CHECK: call void @llvm.dbg.declare({{.*}}metadata ![[UNUSED_VAR:[0-9]+]], metadata !DIExpression())
__block int unused_var;
// Use i (not inside a block).
++unused_var;
}

// CHECK: ![[ESCAPE_VAR]] = !DILocalVariable(name: "escape_var"
// CHECK: ![[NOESCAPE_VAR]] = !DILocalVariable(name: "noescape_var"
// CHECK: ![[BLOCK_VAR]] = !DILocalVariable(name: "block_var"
// CHECK: ![[UNUSED_VAR]] = !DILocalVariable(name: "unused_var"