[llvm] b6cca0e - Revert "[DWARF] Add cuttoff guarding quadratic validThroughout behaviour"
via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 27 04:14:04 PDT 2020
Author: OCHyams
Date: 2020-08-27T11:52:30+01:00
New Revision: b6cca0ec05cfc48f59628f6c4c076756b839f4a2
URL: https://github.com/llvm/llvm-project/commit/b6cca0ec05cfc48f59628f6c4c076756b839f4a2
DIFF: https://github.com/llvm/llvm-project/commit/b6cca0ec05cfc48f59628f6c4c076756b839f4a2.diff
LOG: Revert "[DWARF] Add cuttoff guarding quadratic validThroughout behaviour"
This reverts commit b9d977b0ca60c54f11615ca9d144c9f08b29fd85.
This cutoff is no longer required. The commit 34ffa7fc501 (D86153) introduces a
performance improvement which was tested against the motivating case for this
patch.
Discussed in differential revision: https://reviews.llvm.org/D86153
Added:
Modified:
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
Removed:
llvm/test/DebugInfo/MIR/X86/singlelocation-cutoffs.mir
################################################################################
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 3049e7caf351..64d57aa9402c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -148,11 +148,6 @@ static cl::opt<LinkageNameOption>
"Abstract subprograms")),
cl::init(DefaultLinkageNames));
-static cl::opt<unsigned> LocationAnalysisSizeLimit(
- "singlevarlocation-input-bb-limit",
- cl::desc("Maximum block size to analyze for single-location variables"),
- cl::init(30000), cl::Hidden);
-
static const char *const DWARFGroupName = "dwarf";
static const char *const DWARFGroupDescription = "DWARF Emission";
static const char *const DbgTimerName = "writer";
@@ -1611,10 +1606,8 @@ static bool validThroughout(LexicalScopes &LScopes,
// [1-3) [(reg0, fragment 0, 32), (reg1, fragment 32, 32)]
// [3-4) [(reg1, fragment 32, 32), (123, fragment 64, 32)]
// [4-) [(@g, fragment 0, 96)]
-bool DwarfDebug::buildLocationList(
- SmallVectorImpl<DebugLocEntry> &DebugLoc,
- const DbgValueHistoryMap::Entries &Entries,
- DenseSet<const MachineBasicBlock *> &VeryLargeBlocks) {
+bool DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
+ const DbgValueHistoryMap::Entries &Entries) {
using OpenRange =
std::pair<DbgValueHistoryMap::EntryIndex, DbgValueLoc>;
SmallVector<OpenRange, 4> OpenRanges;
@@ -1710,14 +1703,8 @@ bool DwarfDebug::buildLocationList(
DebugLoc.pop_back();
}
- // If there's a single entry, safe for a single location, and not part of
- // an over-sized basic block, then ask validThroughout whether this
- // location can be represented as a single variable location.
- if (DebugLoc.size() != 1 || !isSafeForSingleLocation)
- return false;
- if (VeryLargeBlocks.count(StartDebugMI->getParent()))
- return false;
- return validThroughout(LScopes, StartDebugMI, EndMI, getInstOrdering());
+ return DebugLoc.size() == 1 && isSafeForSingleLocation &&
+ validThroughout(LScopes, StartDebugMI, EndMI, getInstOrdering());
}
DbgEntity *DwarfDebug::createConcreteEntity(DwarfCompileUnit &TheCU,
@@ -1749,13 +1736,6 @@ void DwarfDebug::collectEntityInfo(DwarfCompileUnit &TheCU,
// Grab the variable info that was squirreled away in the MMI side-table.
collectVariableInfoFromMFTable(TheCU, Processed);
- // Identify blocks that are unreasonably sized, so that we can later
- // skip lexical scope analysis over them.
- DenseSet<const MachineBasicBlock *> VeryLargeBlocks;
- for (const auto &MBB : *CurFn)
- if (MBB.size() > LocationAnalysisSizeLimit)
- VeryLargeBlocks.insert(&MBB);
-
for (const auto &I : DbgValues) {
InlinedEntity IV = I.first;
if (Processed.count(IV))
@@ -1792,8 +1772,7 @@ void DwarfDebug::collectEntityInfo(DwarfCompileUnit &TheCU,
if (HistSize == 1 || SingleValueWithClobber) {
const auto *End =
SingleValueWithClobber ? HistoryMapEntries[1].getInstr() : nullptr;
- if (VeryLargeBlocks.count(MInsn->getParent()) == 0 &&
- validThroughout(LScopes, MInsn, End, getInstOrdering())) {
+ if (validThroughout(LScopes, MInsn, End, getInstOrdering())) {
RegVar->initializeDbgValue(MInsn);
continue;
}
@@ -1808,8 +1787,7 @@ void DwarfDebug::collectEntityInfo(DwarfCompileUnit &TheCU,
// Build the location list for this variable.
SmallVector<DebugLocEntry, 8> Entries;
- bool isValidSingleLocation =
- buildLocationList(Entries, HistoryMapEntries, VeryLargeBlocks);
+ bool isValidSingleLocation = buildLocationList(Entries, HistoryMapEntries);
// Check whether buildLocationList managed to merge all locations to one
// that is valid throughout the variable's scope. If so, produce single
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index a97d3680412b..ba0bb8436703 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -598,10 +598,8 @@ class DwarfDebug : public DebugHandlerBase {
/// function that describe the same variable. If the resulting
/// list has only one entry that is valid for entire variable's
/// scope return true.
- bool buildLocationList(
- SmallVectorImpl<DebugLocEntry> &DebugLoc,
- const DbgValueHistoryMap::Entries &Entries,
- DenseSet<const MachineBasicBlock *> &VeryLargeBlocks);
+ bool buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
+ const DbgValueHistoryMap::Entries &Entries);
/// Collect variable information from the side table maintained by MF.
void collectVariableInfoFromMFTable(DwarfCompileUnit &TheCU,
diff --git a/llvm/test/DebugInfo/MIR/X86/singlelocation-cutoffs.mir b/llvm/test/DebugInfo/MIR/X86/singlelocation-cutoffs.mir
deleted file mode 100644
index 6ad64d9d74bb..000000000000
--- a/llvm/test/DebugInfo/MIR/X86/singlelocation-cutoffs.mir
+++ /dev/null
@@ -1,65 +0,0 @@
-# Test cutoffs for single-location variable analysis.
-# Disable validThroughout if the input size exceeds the specified limit
-
-# RUN: llc %s -o - -start-after=livedebugvalues -mtriple=x86_64-unknown-unknown \
-# RUN: --singlevarlocation-input-bb-limit=0 -filetype=obj\
-# RUN: | llvm-dwarfdump -v -\
-# RUN: | FileCheck %s -check-prefix=LIMITED
-
-# RUN: llc %s -o - -start-after=livedebugvalues -mtriple=x86_64-unknown-unknown \
-# RUN: --singlevarlocation-input-bb-limit=20 -filetype=obj | llvm-dwarfdump -v -\
-# RUN: | FileCheck %s -check-prefix=UNLIMITED
-
-# LIMITED: DW_AT_location [DW_FORM_sec_offset]
-
-# UNLIMITED: DW_AT_location [DW_FORM_exprloc]
-
---- |
- target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
-
- declare i32 @use(i32)
-
- define i32 @foo(i32 %x) !dbg !6 {
- entry:
- ret i32 1, !dbg !15
- }
-
- declare void @llvm.dbg.value(metadata, metadata, metadata)
-
- !llvm.dbg.cu = !{!0}
- !llvm.debugify = !{!3, !4}
- !llvm.module.flags = !{!5}
-
- !0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
- !1 = !DIFile(filename: "/tmp/t.ll", directory: "/")
- !2 = !{}
- !3 = !{i32 4}
- !4 = !{i32 2}
- !5 = !{i32 2, !"Debug Info Version", i32 3}
- !6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
- !7 = !DISubroutineType(types: !2)
- !8 = !{!9, !11}
- !9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
- !10 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
- !11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 3, type: !10)
- !12 = !DILocation(line: 1, column: 1, scope: !6)
- !13 = !DILocation(line: 2, column: 1, scope: !6)
- !14 = !DILocation(line: 3, column: 1, scope: !6)
- !15 = !DILocation(line: 4, column: 1, scope: !6)
-
-...
----
-name: foo
-liveins:
- - { reg: '$edi', virtual-reg: '' }
-stack:
- - { id: 0, name: '', type: spill-slot, offset: -12, size: 4, alignment: 4,
- stack-id: default, callee-saved-register: '', callee-saved-restored: true,
- debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
-body: |
- bb.0.entry:
- liveins: $edi
- DBG_VALUE renamable $edi, $noreg, !11, !DIExpression(), debug-location !14
- RETQ debug-location !14
-
-...
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