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48bac26038
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
48 lines
1.8 KiB
LLVM
48 lines
1.8 KiB
LLVM
; RUN: llc -mtriple=x86_64-unknown-unknown -o - %s | FileCheck %s
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; RUN: llc -mtriple=x86_64-unknown-unknown -filetype=obj < %s \
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; RUN: | llvm-dwarfdump -v - | FileCheck %s --check-prefix=DWARF
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define i1 @test() !dbg !4 {
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entry:
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%end = alloca i64, align 8
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br label %while.cond
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while.cond:
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call void @llvm.dbg.value(metadata i64* %end, metadata !5, metadata !6), !dbg !7
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%call = call i1 @fn(i64* %end, i64* %end, i64* null, i8* null, i64 0, i64* null, i32* null, i8* null), !dbg !7
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br label %while.body
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while.body:
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br i1 0, label %while.end, label %while.cond
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while.end:
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ret i1 true
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}
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; CHECK-LABEL: test
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; To get the value of the variable, we need to do [$rsp+8], i.e:
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; CHECK: #DEBUG_VALUE: test:w <- [DW_OP_plus_uconst 8, DW_OP_deref] $rsp
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; DWARF: DW_AT_location [DW_FORM_sec_offset] (
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; DWARF-NEXT: [{{.*}}, {{.*}}): DW_OP_breg7 RSP+8)
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; Note: A previous version of this test checked for `[DW_OP_plus_uconst 8] [$rsp+0]`,
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; which is incorrect, because it adds the stack offset after dereferencing the stack pointer.
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declare i1 @fn(i64*, i64*, i64*, i8*, i64, i64*, i32*, i8*)
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2,!3}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0", emissionKind: FullDebug)
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!1 = !DIFile(filename: "test.c", directory: "/")
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!2 = !{i32 2, !"Dwarf Version", i32 4}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = distinct !DISubprogram(name: "test", type: !10, unit: !0)
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!5 = !DILocalVariable(name: "w", scope: !4, type: !9)
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!6 = !DIExpression(DW_OP_deref)
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!7 = !DILocation(line: 210, column: 12, scope: !4)
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!8 = !{!9}
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!9 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
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!10 = !DISubroutineType(types: !8)
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