From b572f6421296e7688973014d253e46c54fd64ba3 Mon Sep 17 00:00:00 2001 From: Vedant Kumar Date: Thu, 26 Jul 2018 20:56:53 +0000 Subject: [DebugInfo] LowerDbgDeclare: Add derefs when handling CallInst users LowerDbgDeclare inserts a dbg.value before each use of an address described by a dbg.declare. When inserting a dbg.value before a CallInst use, however, it fails to append DW_OP_deref to the DIExpression. The DW_OP_deref is needed to reflect the fact that a dbg.value describes a source variable directly (as opposed to a dbg.declare, which relies on pointer indirection). This patch adds in the DW_OP_deref where needed. This results in the correct values being shown during a debug session for a program compiled with ASan and optimizations (see https://reviews.llvm.org/D49520). Note that ConvertDebugDeclareToDebugValue is already correct -- no changes there were needed. One complication is that SelectionDAG is unable to distinguish between direct and indirect frame-index (FRAMEIX) SDDbgValues. This patch also fixes this long-standing issue in order to not regress integration tests relying on the incorrect assumption that all frame-index SDDbgValues are indirect. This is a necessary fix: the newly-added DW_OP_derefs cannot be lowered properly otherwise. Basically the fix prevents a direct SDDbgValue with DIExpression(DW_OP_deref) from being dereferenced twice by a debugger. There were a handful of tests relying on this incorrect "FRAMEIX => indirect" assumption which actually had incorrect DW_AT_locations: these are all fixed up in this patch. Testing: - check-llvm, and an end-to-end test using lldb to debug an optimized program. - Existing unit tests for DIExpression::appendToStack fully cover the new DIExpression::append utility. - check-debuginfo (the debug info integration tests) Differential Revision: https://reviews.llvm.org/D49454 llvm-svn: 338069 --- llvm/unittests/IR/MetadataTest.cpp | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'llvm/unittests') diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp index 12256bd2366..84a7b02fa98 100644 --- a/llvm/unittests/IR/MetadataTest.cpp +++ b/llvm/unittests/IR/MetadataTest.cpp @@ -2111,14 +2111,20 @@ TEST_F(DIExpressionTest, get) { // Test DIExpression::prepend(). uint64_t Elts0[] = {dwarf::DW_OP_LLVM_fragment, 0, 32}; auto *N0 = DIExpression::get(Context, Elts0); - N0 = DIExpression::prepend(N0, true, 64, true, true); + auto *N0WithPrependedOps = DIExpression::prepend(N0, true, 64, true, true); uint64_t Elts1[] = {dwarf::DW_OP_deref, dwarf::DW_OP_plus_uconst, 64, dwarf::DW_OP_deref, dwarf::DW_OP_stack_value, dwarf::DW_OP_LLVM_fragment, 0, 32}; auto *N1 = DIExpression::get(Context, Elts1); - EXPECT_EQ(N0, N1); + EXPECT_EQ(N0WithPrependedOps, N1); + + // Test DIExpression::append(). + uint64_t Elts2[] = {dwarf::DW_OP_deref, dwarf::DW_OP_plus_uconst, 64, + dwarf::DW_OP_deref, dwarf::DW_OP_stack_value}; + auto *N2 = DIExpression::append(N0, Elts2); + EXPECT_EQ(N0WithPrependedOps, N2); } TEST_F(DIExpressionTest, isValid) { -- cgit v1.2.3