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[NFC] Allow fragment expressions in extractIfOffset #69006

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[NFC] Allow fragment expressions in extractIfOffset #69006

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9 changes: 6 additions & 3 deletions llvm/lib/IR/DebugInfoMetadata.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1673,18 +1673,21 @@ bool DIExpression::extractIfOffset(int64_t &Offset) const {
return false;
auto SingleLocElts = *SingleLocEltsOpt;

if (SingleLocElts.size() == 0) {
unsigned FragmentOpsCount = isFragment() ? 3 : 0;

if (SingleLocElts.size() == FragmentOpsCount) {
Offset = 0;
return true;
}

if (SingleLocElts.size() == 2 &&
if (SingleLocElts.size() == 2 + FragmentOpsCount &&
SingleLocElts[0] == dwarf::DW_OP_plus_uconst) {
Offset = SingleLocElts[1];
return true;
}

if (SingleLocElts.size() == 3 && SingleLocElts[0] == dwarf::DW_OP_constu) {
if (SingleLocElts.size() == 3 + FragmentOpsCount &&
SingleLocElts[0] == dwarf::DW_OP_constu) {
if (SingleLocElts[2] == dwarf::DW_OP_plus) {
Offset = SingleLocElts[1];
return true;
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51 changes: 51 additions & 0 deletions llvm/unittests/IR/MetadataTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3511,6 +3511,57 @@ TEST_F(DIExpressionTest, isEqualExpression) {
#undef GET_EXPR
}

TEST_F(DIExpressionTest, extractIfOffset) {
#define GET_EXPR(...) DIExpression::get(Context, {__VA_ARGS__})
#define GET_FRAG(...) \
DIExpression::get(Context, {__VA_ARGS__, dwarf::DW_OP_LLVM_fragment, 0, 32})
#define EXPECT_OFFSET_IMPL(Offset, Success, Expr) \
do { \
int64_t ActualOffset; \
bool Result = Expr->extractIfOffset(ActualOffset); \
EXPECT_EQ(Success, Result); \
if (Success) { \
EXPECT_EQ(Offset, ActualOffset); \
} \
} while (0)
#define EXPECT_OFFSET_EQ(Offset, Expr) EXPECT_OFFSET_IMPL(Offset, true, Expr)
#define EXPECT_NO_OFFSET(Expr) EXPECT_OFFSET_IMPL(0, false, Expr)

// Check extractIfOffset behaves as expected with and without a fragment
// in the expression. extractIfOffset reads a constant offset out from the
// expression. It fails for all but exactly these with and without fragments:
// no expression
// DW_OP_plus_uconst, <u>
// DW_OP_constu, <u>, DW_OP_plus/minus
EXPECT_OFFSET_EQ(0, GET_EXPR());
EXPECT_OFFSET_EQ(0, GET_EXPR(dwarf::DW_OP_LLVM_fragment, 0, 32));

EXPECT_OFFSET_EQ(1, GET_EXPR(dwarf::DW_OP_plus_uconst, 1));
EXPECT_OFFSET_EQ(1, GET_FRAG(dwarf::DW_OP_plus_uconst, 1));

EXPECT_OFFSET_EQ(2, GET_EXPR(dwarf::DW_OP_constu, 2, dwarf::DW_OP_plus));
EXPECT_OFFSET_EQ(2, GET_FRAG(dwarf::DW_OP_constu, 2, dwarf::DW_OP_plus));

EXPECT_OFFSET_EQ(-3, GET_EXPR(dwarf::DW_OP_constu, 3, dwarf::DW_OP_minus));
EXPECT_OFFSET_EQ(-3, GET_FRAG(dwarf::DW_OP_constu, 3, dwarf::DW_OP_minus));

// Test some failure cases, e.g. unsupported operations and too many
// operations.
EXPECT_NO_OFFSET(GET_EXPR(dwarf::DW_OP_constu, 3, dwarf::DW_OP_mul));
EXPECT_NO_OFFSET(GET_FRAG(dwarf::DW_OP_constu, 3, dwarf::DW_OP_mul));

EXPECT_NO_OFFSET(
GET_EXPR(dwarf::DW_OP_constu, 3, dwarf::DW_OP_plus, dwarf::DW_OP_deref));
EXPECT_NO_OFFSET(
GET_FRAG(dwarf::DW_OP_constu, 3, dwarf::DW_OP_plus, dwarf::DW_OP_deref));

#undef EXPECT_NO_OFFSET
#undef EXPECT_OFFSET_EQ
#undef EXPECT_OFFSET_IMPL
#undef GET_FRAG
#undef GET_EXPR
}

TEST_F(DIExpressionTest, foldConstant) {
const ConstantInt *Int;
const ConstantInt *NewInt;
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