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[DebugInfo] Correctly handle salvaged casts and split fragments at ISel

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Previously, LLVM had no functional way of performing casts inside of a
DIExpression(), which made salvaging cast instructions other than Noop
casts impossible. This patch enables the salvaging of casts by using the
DW_OP_LLVM_convert operator for SExt and Trunc instructions.

There is another issue which is exposed by this fix, in which fragment
DIExpressions (which are preserved more readily by this patch) for
values that must be split across registers in ISel trigger an assertion,
as the 'split' fragments extend beyond the bounds of the fragment
DIExpression causing an error. This patch also fixes this issue by
checking the fragment status of DIExpressions which are to be split, and
dropping fragments that are invalid.
This commit is contained in:
stozer 2019-12-17 09:37:17 +00:00
parent bc5b7e21e3
commit bb1b0bc4e5
11 changed files with 156 additions and 19 deletions
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5
llvm/include/llvm/IR/DebugInfoMetadata.h
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@ -2552,6 +2552,11 @@ public:
return 0;
}
using ExtOps = std::array<uint64_t, 6>;
/// Returns the ops for a zero- or sign-extension in a DIExpression.
static ExtOps getExtOps(unsigned FromSize, unsigned ToSize, bool Signed);
/// Append a zero- or sign-extension to \p Expr. Converts the expression to a
/// stack value if it isn't one already.
static DIExpression *appendExt(const DIExpression *Expr, unsigned FromSize,

21
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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@ -5571,8 +5571,26 @@ bool SelectionDAGBuilder::EmitFuncArgumentDbgValue(
= [&](ArrayRef<std::pair<unsigned, unsigned>> SplitRegs) {
unsigned Offset = 0;
for (auto RegAndSize : SplitRegs) {
// If the expression is already a fragment, the current register
// offset+size might extend beyond the fragment. In this case, only
// the register bits that are inside the fragment are relevant.
int RegFragmentSizeInBits = RegAndSize.second;
if (auto ExprFragmentInfo = Expr->getFragmentInfo()) {
uint64_t ExprFragmentSizeInBits = ExprFragmentInfo->SizeInBits;
// The register is entirely outside the expression fragment,
// so is irrelevant for debug info.
if (Offset >= ExprFragmentSizeInBits)
break;
// The register is partially outside the expression fragment, only
// the low bits within the fragment are relevant for debug info.
if (Offset + RegFragmentSizeInBits > ExprFragmentSizeInBits) {
RegFragmentSizeInBits = ExprFragmentSizeInBits - Offset;
}
}
auto FragmentExpr = DIExpression::createFragmentExpression(
Expr, Offset, RegAndSize.second);
Expr, Offset, RegFragmentSizeInBits);
Offset += RegAndSize.second;
// If a valid fragment expression cannot be created, the variable's
// correct value cannot be determined and so it is set as Undef.
if (!FragmentExpr) {
@ -5585,7 +5603,6 @@ bool SelectionDAGBuilder::EmitFuncArgumentDbgValue(
FuncInfo.ArgDbgValues.push_back(
BuildMI(MF, DL, TII->get(TargetOpcode::DBG_VALUE), false,
RegAndSize.first, Variable, *FragmentExpr));
Offset += RegAndSize.second;
}
};

13
llvm/lib/IR/DebugInfoMetadata.cpp
View File

@ -1196,13 +1196,18 @@ bool DIExpression::isConstant() const {
return true;
}
DIExpression::ExtOps DIExpression::getExtOps(unsigned FromSize, unsigned ToSize,
bool Signed) {
dwarf::TypeKind TK = Signed ? dwarf::DW_ATE_signed : dwarf::DW_ATE_unsigned;
DIExpression::ExtOps Ops({dwarf::DW_OP_LLVM_convert, FromSize, TK,
dwarf::DW_OP_LLVM_convert, ToSize, TK});
return Ops;
}
DIExpression *DIExpression::appendExt(const DIExpression *Expr,
unsigned FromSize, unsigned ToSize,
bool Signed) {
dwarf::TypeKind TK = Signed ? dwarf::DW_ATE_signed : dwarf::DW_ATE_unsigned;
uint64_t Ops[] = {dwarf::DW_OP_LLVM_convert, FromSize, TK,
dwarf::DW_OP_LLVM_convert, ToSize, TK};
return appendToStack(Expr, Ops);
return appendToStack(Expr, getExtOps(FromSize, ToSize, Signed));
}
DIGlobalVariableExpression *

22
llvm/lib/Transforms/Utils/Local.cpp
View File

@ -1676,9 +1676,8 @@ DIExpression *llvm::salvageDebugInfoImpl(Instruction &I,
};
// initializer-list helper for applying operators to the source DIExpression.
auto applyOps =
[&](std::initializer_list<uint64_t> Opcodes) -> DIExpression * {
SmallVector<uint64_t, 8> Ops(Opcodes);
auto applyOps = [&](ArrayRef<uint64_t> Opcodes) -> DIExpression * {
SmallVector<uint64_t, 8> Ops(Opcodes.begin(), Opcodes.end());
return doSalvage(Ops);
};
@ -1686,8 +1685,21 @@ DIExpression *llvm::salvageDebugInfoImpl(Instruction &I,
// No-op casts and zexts are irrelevant for debug info.
if (CI->isNoopCast(DL) || isa<ZExtInst>(&I))
return SrcDIExpr;
return nullptr;
} else if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
Type *Type = CI->getType();
// Casts other than Trunc or SExt to scalar types cannot be salvaged.
if (Type->isVectorTy() || (!isa<TruncInst>(&I) && !isa<SExtInst>(&I)))
return nullptr;
Value *FromValue = CI->getOperand(0);
unsigned FromTypeBitSize = FromValue->getType()->getScalarSizeInBits();
unsigned ToTypeBitSize = Type->getScalarSizeInBits();
return applyOps(DIExpression::getExtOps(FromTypeBitSize, ToTypeBitSize,
isa<SExtInst>(&I)));
}
if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
unsigned BitWidth =
M.getDataLayout().getIndexSizeInBits(GEP->getPointerAddressSpace());
// Rewrite a constant GEP into a DIExpression.

72
llvm/test/CodeGen/ARM/fragmented-args-multiple-regs.ll Normal file
View File

@ -0,0 +1,72 @@
; RUN: llc < %s -mtriple=armv7-linux-gnueabihf -O1 -stop-after=finalize-isel | FileCheck %s
define dso_local i32 @h(i64 %j) local_unnamed_addr !dbg !8 {
entry:
call void @llvm.dbg.value(metadata i64 %j, metadata !14, metadata !DIExpression()), !dbg !29
call void @llvm.dbg.value(metadata i64 %j, metadata !15, metadata !DIExpression(DW_OP_LLVM_convert, 64, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32)), !dbg !29
call void @llvm.dbg.value(metadata i64 %j, metadata !15, metadata !DIExpression(DW_OP_constu, 32, DW_OP_shr, DW_OP_LLVM_convert, 64, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value, DW_OP_LLVM_fragment, 32, 32)), !dbg !29
%tobool = icmp ult i64 %j, 4294967296, !dbg !30
br i1 %tobool, label %cleanup, label %if.then, !dbg !31
if.then: ; preds = %entry
call void @llvm.dbg.value(metadata i64 %j, metadata !15, metadata !DIExpression(DW_OP_LLVM_convert, 64, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value, DW_OP_LLVM_fragment, 0, 32)), !dbg !29
%conv = sitofp i64 %j to double, !dbg !32
%add = fadd double %conv, 0x43F0000000000000, !dbg !33
call void @llvm.dbg.value(metadata double %add, metadata !25, metadata !DIExpression()), !dbg !34
%conv2 = fptosi double %add to i32, !dbg !35
br label %cleanup
cleanup: ; preds = %entry, %if.then
%retval.0 = phi i32 [ %conv2, %if.then ], [ undef, %entry ]
ret i32 %retval.0, !dbg !36
}
; CHECK-LABEL: bb.0.entry:
; CHECK: DBG_VALUE [[REG1:%[0-9]+]], $noreg, !14, !DIExpression(DW_OP_LLVM_fragment, 32, 32
; CHECK: DBG_VALUE [[REG2:%[0-9]+]], $noreg, !14, !DIExpression(DW_OP_LLVM_fragment, 0, 32
; CHECK: DBG_VALUE [[REG2]], $noreg, !15, !DIExpression({{.+}}DW_OP_LLVM_fragment, 0, 32
; CHECK: DBG_VALUE $noreg, $noreg, !15, !DIExpression({{.+}}DW_OP_LLVM_fragment, 32, 32
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "tif_aux.c", directory: "/tmp")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 1, !"min_enum_size", i32 4}
!7 = !{!"clang version 10.0.0 "}
!8 = distinct !DISubprogram(name: "h", scope: !1, file: !1, line: 10, type: !9, scopeLine: 10, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
!9 = !DISubroutineType(types: !10)
!10 = !{!11, !12}
!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!12 = !DIBasicType(name: "long long int", size: 64, encoding: DW_ATE_signed)
!13 = !{!14, !15, !25}
!14 = !DILocalVariable(name: "j", arg: 1, scope: !8, file: !1, line: 10, type: !12)
!15 = !DILocalVariable(name: "i", scope: !8, file: !1, line: 11, type: !16)
!16 = !DIDerivedType(tag: DW_TAG_typedef, name: "g", file: !1, line: 8, baseType: !17)
!17 = distinct !DICompositeType(tag: DW_TAG_union_type, file: !1, line: 5, size: 64, elements: !18)
!18 = !{!19, !24}
!19 = !DIDerivedType(tag: DW_TAG_member, name: "e", scope: !17, file: !1, line: 6, baseType: !20, size: 64)
!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "b", file: !1, line: 1, size: 64, elements: !21)
!21 = !{!22, !23}
!22 = !DIDerivedType(tag: DW_TAG_member, name: "c", scope: !20, file: !1, line: 2, baseType: !11, size: 32)
!23 = !DIDerivedType(tag: DW_TAG_member, name: "d", scope: !20, file: !1, line: 2, baseType: !11, size: 32, offset: 32)
!24 = !DIDerivedType(tag: DW_TAG_member, name: "f", scope: !17, file: !1, line: 7, baseType: !12, size: 64)
!25 = !DILocalVariable(name: "a", scope: !26, file: !1, line: 14, type: !28)
!26 = distinct !DILexicalBlock(scope: !27, file: !1, line: 13, column: 14)
!27 = distinct !DILexicalBlock(scope: !8, file: !1, line: 13, column: 7)
!28 = !DIBasicType(name: "double", size: 64, encoding: DW_ATE_float)
!29 = !DILocation(line: 0, scope: !8)
!30 = !DILocation(line: 13, column: 7, scope: !27)
!31 = !DILocation(line: 13, column: 7, scope: !8)
!32 = !DILocation(line: 14, column: 16, scope: !26)
!33 = !DILocation(line: 14, column: 20, scope: !26)
!34 = !DILocation(line: 0, scope: !26)
!35 = !DILocation(line: 15, column: 12, scope: !26)
!36 = !DILocation(line: 17, column: 1, scope: !8)

4
llvm/test/DebugInfo/X86/dbg-value-dropped-instcombine.ll
View File

@ -21,8 +21,8 @@
; }
; CHECK: define dso_local i64 @foo
; CHECK: @llvm.dbg.value({{.*}}, metadata ![[BEE:[0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)),
; CHECK: @llvm.dbg.value(metadata i32 undef, metadata ![[BEE]], metadata !DIExpression(DW_OP_LLVM_fragment, 32, 32)),
; CHECK: @llvm.dbg.value(metadata i64 {{.*}}, metadata ![[BEE:[0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 32)),
; CHECK: @llvm.dbg.value(metadata i64 {{.*}}, metadata ![[BEE]], metadata !DIExpression({{.*}}, DW_OP_LLVM_fragment, 32, 32)),
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-unknown"

25
llvm/test/DebugInfo/salvage-cast-debug-info.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: opt %s -debugify -early-cse -S | FileCheck %s
define i32 @foo(i64 %nose, i32 %more) {
; CHECK-LABEL: @foo(
; CHECK: call void @llvm.dbg.value(metadata i64 %nose, metadata [[V1:![0-9]+]], metadata !DIExpression(DW_OP_LLVM_convert, 64, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned
; CHECK: call void @llvm.dbg.value(metadata i64 %nose.shift, metadata [[V2:![0-9]+]]
; CHECK: call void @llvm.dbg.value(metadata i64 %nose.shift, metadata [[V3:![0-9]+]], metadata !DIExpression(DW_OP_LLVM_convert, 64, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned
entry:
%nose.trunc = trunc i64 %nose to i32
%nose.shift = lshr i64 %nose, 32
%nose.trunc.2 = trunc i64 %nose.shift to i32
%add = add nsw i32 %more, 1
ret i32 %add
}
!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}
!0 = !{i32 1, !"wchar_size", i32 2}
!1 = !{i32 7, !"PIC Level", i32 2}
!2 = !{!"clang version 10.0.0 "}
; CHECK: [[V1]] = !DILocalVariable(
; CHECK: [[V2]] = !DILocalVariable(
; CHECK: [[V3]] = !DILocalVariable(

2
llvm/test/Transforms/EarlyCSE/debug-info-undef.ll
View File

@ -10,7 +10,7 @@ entry:
%0 = load i8, i8* @a, align 1, !dbg !19, !tbaa !20
%conv = sext i8 %0 to i16, !dbg !19
; CHECK: call void @llvm.dbg.value(metadata i16 undef, metadata !17, metadata !DIExpression()), !dbg !18
; CHECK: call void @llvm.dbg.value(metadata i8 %0, metadata !17, metadata !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 16, DW_ATE_signed, DW_OP_stack_value)), !dbg !18
; CHECK-NEXT: call i32 (...) @optimize_me_not()
call void @llvm.dbg.value(metadata i16 %conv, metadata !17, metadata !DIExpression()), !dbg !18

4
llvm/test/Transforms/InstCombine/cast-mul-select.ll
View File

@ -13,8 +13,8 @@ define i32 @mul(i32 %x, i32 %y) {
; we preserve the debug information in the resulting
; instruction.
; DBGINFO-LABEL: @mul(
; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i8 undef
; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i8 undef
; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i32 %x
; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i32 %y
; DBGINFO-NEXT: [[C:%.*]] = mul i32 {{.*}}
; DBGINFO-NEXT: [[D:%.*]] = and i32 {{.*}}
; DBGINFO-NEXT: call void @llvm.dbg.value(metadata i32 [[C]]

5
llvm/test/Transforms/InstCombine/pr43893.ll
View File

@ -13,9 +13,10 @@ entry:
;CHECK: call void @llvm.dbg.value(metadata i32 -8
;CHECK: call void @llvm.dbg.value(metadata i32 undef
%conv = sext i8 %dec to i32, !dbg !17
call void @llvm.dbg.value(metadata i32 %conv, metadata !18, metadata !DIExpression()), !dbg !19
%udiv = udiv i32 %conv, 4, !dbg !17
call void @llvm.dbg.value(metadata i32 %udiv, metadata !18, metadata !DIExpression()), !dbg !19
call void @llvm.dbg.value(metadata i32 -8, metadata !20, metadata !DIExpression()), !dbg !19
call void @llvm.dbg.value(metadata i32 %conv, metadata !20, metadata !DIExpression()), !dbg !19
call void @llvm.dbg.value(metadata i32 %udiv, metadata !20, metadata !DIExpression()), !dbg !19
store i8 0, i8* @b, align 1, !dbg !21
%cmp = icmp sgt i32 %conv, 0, !dbg !22
%conv1 = zext i1 %cmp to i32, !dbg !22

2
llvm/test/Transforms/InstCombine/unavailable-debug.ll
View File

@ -2,7 +2,7 @@
; Make sure to update the debug value after dead code elimination.
; CHECK: %call = call signext i8 @b(i32 6), !dbg !39
; CHECK-NEXT: call void @llvm.dbg.value(metadata i32 undef, metadata !30, metadata !DIExpression()), !dbg !38
; CHECK-NEXT: call void @llvm.dbg.value(metadata i8 %call, metadata !30, metadata !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_signed, DW_OP_LLVM_convert, 32, DW_ATE_signed, DW_OP_stack_value)), !dbg !38
@e = common local_unnamed_addr global i8 0, align 1, !dbg !0
@c = common local_unnamed_addr global i32 0, align 4, !dbg !6