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[Utils] Insert DW_OP_bit_piece when only describing part of the variable 

Summary: The dbg.declare -> dbg.value conversion looks through any zext/sext
to find a value to describe the variable (in the expectation that those
zext/sext instruction will go away later). However, those values do not
cover the entire variable and thus need a DW_OP_bit_piece.

Reviewers: aprantl
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D16061

llvm-svn: 257534
This commit is contained in:
Keno Fischer 2016-01-12 22:46:09 +00:00
parent bc68758dd5
commit 9aae445e09
2 changed files with 69 additions and 2 deletions
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26
llvm/lib/Transforms/Utils/Local.cpp
View File

@ -1052,9 +1052,31 @@ bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
ExtendedArg = dyn_cast<Argument>(ZExt->getOperand(0));
if (SExtInst *SExt = dyn_cast<SExtInst>(SI->getOperand(0)))
ExtendedArg = dyn_cast<Argument>(SExt->getOperand(0));
if (ExtendedArg)
Builder.insertDbgValueIntrinsic(ExtendedArg, 0, DIVar, DIExpr,
if (ExtendedArg) {
// We're now only describing a subset of the variable. The piece we're
// describing will always be smaller than the variable size, because
// VariableSize == Size of Alloca described by DDI. Since SI stores
// to the alloca described by DDI, if it's first operand is an extend,
// we're guaranteed that before extension, the value was narrower than
// the size of the alloca, hence the size of the described variable.
SmallVector<uint64_t, 3> NewDIExpr;
unsigned PieceOffset = 0;
// If this already is a bit piece, we drop the bit piece from the expression
// and record the offset.
if (DIExpr->isBitPiece()) {
NewDIExpr.append(DIExpr->elements_begin(), DIExpr->elements_end()-3);
PieceOffset = DIExpr->getBitPieceOffset();
} else {
NewDIExpr.append(DIExpr->elements_begin(), DIExpr->elements_end());
}
NewDIExpr.push_back(dwarf::DW_OP_bit_piece);
NewDIExpr.push_back(PieceOffset); //Offset
const DataLayout &DL = DDI->getModule()->getDataLayout();
NewDIExpr.push_back(DL.getTypeSizeInBits(ExtendedArg->getType())); // Size
Builder.insertDbgValueIntrinsic(ExtendedArg, 0, DIVar,
Builder.createExpression(NewDIExpr),
DDI->getDebugLoc(), SI);
}
else
Builder.insertDbgValueIntrinsic(SI->getOperand(0), 0, DIVar, DIExpr,
DDI->getDebugLoc(), SI);

45
llvm/test/Transforms/Util/split-bit-piece.ll Normal file
View File

@ -0,0 +1,45 @@
; Checks that llvm.dbg.declare -> llvm.dbg.value conversion utility
; (here exposed through the SROA) pass, properly inserts bit_piece expressions
; if it only describes part of the variable.
; RUN: opt -S -sroa %s | FileCheck %s
; Function Attrs: nounwind readnone
declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
; Function Attrs: nounwind uwtable
define hidden void @_ZN6__tsan9FastState14SetHistorySizeEi(i32 %hs) #1 align 2 {
entry:
%hs.addr = alloca i32, align 4
%v1 = alloca i64, align 8
%v2 = alloca i64, align 8
store i32 %hs, i32* %hs.addr, align 4
; CHECK: call void @llvm.dbg.value(metadata i32 %hs, i64 0, metadata !{{[0-9]+}}, metadata ![[EXPR:[0-9]+]])
; CHECK: ![[EXPR]] = !DIExpression(DW_OP_bit_piece, 0
call void @llvm.dbg.declare(metadata i64* %v1, metadata !9, metadata !12), !dbg !13
%0 = load i32, i32* %hs.addr, align 4
%conv = sext i32 %0 to i64
store i64 %conv, i64* %v1, align 8
%1 = load i64, i64* %v2, align 8
unreachable
}
attributes #0 = { nounwind readnone }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!7}
!llvm.ident = !{!8}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 256979) (llvm/trunk 257107)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, retainedTypes: !2)
!1 = !DIFile(filename: "tsan_shadow_test.cc", directory: "/tmp")
!2 = !{!3, !5}
!3 = !DICompositeType(tag: DW_TAG_class_type, name: "FastState", file: !4, line: 91, size: 64, align: 64, identifier: "_ZTSN6__tsan9FastStateE")
!4 = !DIFile(filename: "/mnt/extra/llvm/projects/compiler-rt/lib/tsan/rtl/tsan_rtl.h", directory: "/tmp")
!5 = distinct !DIDerivedType(tag: DW_TAG_typedef, name: "u64", line: 78, baseType: !6)
!6 = !DIBasicType(name: "long long unsigned int", size: 64, align: 64, encoding: DW_ATE_unsigned)
!7 = !{i32 2, !"Debug Info Version", i32 3}
!8 = !{!"clang version 3.8.0 (trunk 256979) (llvm/trunk 257107)"}
!9 = !DILocalVariable(name: "v1", scope: !10, file: !4, line: 136, type: !5)
!10 = distinct !DILexicalBlock(scope: !11, file: !4, line: 136, column: 5)
!11 = distinct !DISubprogram(name: "SetHistorySize", linkageName: "_ZN6__tsan9FastState14SetHistorySizeEi", scope: !"_ZTSN6__tsan9FastStateE", file: !4, line: 135, isLocal: false, isDefinition: true, scopeLine: 135, flags: DIFlagPrototyped, isOptimized: false)
!12 = !DIExpression()
!13 = !DILocation(line: 136, column: 5, scope: !10)