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[DebugInfo] Disallow fragmenting DIExpressions with shift operators 

DIExpressions with shift operators should not be fragmented for the same
reason as arithmetic operators: carry over cannot be expressed from one
fragment to the other, so an invalid result would be produced.

Differential Revision: https://reviews.llvm.org/D70601
This commit is contained in:
stozer 2019-11-22 16:40:32 +00:00
parent 7707d8aa9d
commit 184d72a7c6
2 changed files with 49 additions and 2 deletions
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8
llvm/lib/IR/DebugInfoMetadata.cpp
View File

@ -1148,10 +1148,14 @@ Optional<DIExpression *> DIExpression::createFragmentExpression(
for (auto Op : Expr->expr_ops()) { for (auto Op : Expr->expr_ops()) {
switch (Op.getOp()) { switch (Op.getOp()) {
default: break; default: break;
case dwarf::DW_OP_shr:
case dwarf::DW_OP_shra:
case dwarf::DW_OP_shl:
case dwarf::DW_OP_plus: case dwarf::DW_OP_plus:
case dwarf::DW_OP_plus_uconst:
case dwarf::DW_OP_minus: case dwarf::DW_OP_minus:
// We can't safely split arithmetic into multiple fragments because we // We can't safely split arithmetic or shift operations into multiple
// can't express carry-over between fragments. // fragments because we can't express carry-over between fragments.
// //
// FIXME: We *could* preserve the lowest fragment of a constant offset // FIXME: We *could* preserve the lowest fragment of a constant offset
// operation if the offset fits into SizeInBits. // operation if the offset fits into SizeInBits.

43
llvm/unittests/IR/MetadataTest.cpp
View File

@ -2394,6 +2394,49 @@ TEST_F(DIExpressionTest, isValid) {
#undef EXPECT_INVALID #undef EXPECT_INVALID
} }
TEST_F(DIExpressionTest, createFragmentExpression) {
#define EXPECT_VALID_FRAGMENT(Offset, Size, ...) \
do { \
uint64_t Elements[] = {__VA_ARGS__}; \
DIExpression* Expression = DIExpression::get(Context, Elements); \
EXPECT_TRUE(DIExpression::createFragmentExpression( \
Expression, Offset, Size).hasValue()); \
} while (false)
#define EXPECT_INVALID_FRAGMENT(Offset, Size, ...) \
do { \
uint64_t Elements[] = {__VA_ARGS__}; \
DIExpression* Expression = DIExpression::get(Context, Elements); \
EXPECT_FALSE(DIExpression::createFragmentExpression( \
Expression, Offset, Size).hasValue()); \
} while (false)
// createFragmentExpression adds correct ops.
Optional<DIExpression*> R = DIExpression::createFragmentExpression(
DIExpression::get(Context, {}), 0, 32);
EXPECT_EQ(R.hasValue(), true);
EXPECT_EQ(3u, (*R)->getNumElements());
EXPECT_EQ(dwarf::DW_OP_LLVM_fragment, (*R)->getElement(0));
EXPECT_EQ(0u, (*R)->getElement(1));
EXPECT_EQ(32u, (*R)->getElement(2));
// Valid fragment expressions.
EXPECT_VALID_FRAGMENT(0, 32, {});
EXPECT_VALID_FRAGMENT(0, 32, dwarf::DW_OP_deref);
EXPECT_VALID_FRAGMENT(0, 32, dwarf::DW_OP_LLVM_fragment, 0, 32);
EXPECT_VALID_FRAGMENT(16, 16, dwarf::DW_OP_LLVM_fragment, 0, 32);
// Invalid fragment expressions (incompatible ops).
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_constu, 6, dwarf::DW_OP_plus);
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_constu, 14, dwarf::DW_OP_minus);
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_constu, 16, dwarf::DW_OP_shr);
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_constu, 16, dwarf::DW_OP_shl);
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_constu, 16, dwarf::DW_OP_shra);
EXPECT_INVALID_FRAGMENT(0, 32, dwarf::DW_OP_plus_uconst, 6);
#undef EXPECT_VALID_FRAGMENT
#undef EXPECT_INVALID_FRAGMENT
}
typedef MetadataTest DIObjCPropertyTest; typedef MetadataTest DIObjCPropertyTest;
TEST_F(DIObjCPropertyTest, get) { TEST_F(DIObjCPropertyTest, get) {