[llvm] 5f87415 - [LICM] Try to merge debug locations when sinking.
Davide Italiano via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 15 12:29:42 PDT 2020
Author: Davide Italiano
Date: 2020-04-15T12:29:34-07:00
New Revision: 5f87415efc1e57587272944a5f9b6745e4474660
URL: https://github.com/llvm/llvm-project/commit/5f87415efc1e57587272944a5f9b6745e4474660
DIFF: https://github.com/llvm/llvm-project/commit/5f87415efc1e57587272944a5f9b6745e4474660.diff
LOG: [LICM] Try to merge debug locations when sinking.
The current strategy LICM uses when sinking for debuginfo is
that of picking the debug location of one of the uses.
This causes stepping to be wrong sometimes, see, e.g. PR45523.
This patch introduces a generalization of getMergedLocation(),
that operates on a vector of locations instead of two, and try
to merge all them together, and use the new API in LICM.
<rdar://problem/61750950>
Added:
llvm/test/Transforms/LICM/sink-debuginfo-preserve.ll
Modified:
llvm/include/llvm/IR/DebugInfoMetadata.h
llvm/lib/IR/DebugInfoMetadata.cpp
llvm/lib/Transforms/Scalar/LICM.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/IR/DebugInfoMetadata.h b/llvm/include/llvm/IR/DebugInfoMetadata.h
index 6056337fdff1..3eaed3270602 100644
--- a/llvm/include/llvm/IR/DebugInfoMetadata.h
+++ b/llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -1546,6 +1546,13 @@ class DILocation : public MDNode {
static const DILocation *getMergedLocation(const DILocation *LocA,
const DILocation *LocB);
+ /// Try to combine the vector of locations passed as input in a single one.
+ /// This function applies getMergedLocation() repeatedly left-to-right.
+ ///
+ /// \p Locs: The locations to be merged.
+ static
+ const DILocation *getMergedLocations(ArrayRef<const DILocation *> Locs);
+
/// Returns the base discriminator for a given encoded discriminator \p D.
static unsigned getBaseDiscriminatorFromDiscriminator(unsigned D) {
return getUnsignedFromPrefixEncoding(D);
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 740c4bfbbe03..cb4fab0088fb 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -75,6 +75,21 @@ DILocation *DILocation::getImpl(LLVMContext &Context, unsigned Line,
Storage, Context.pImpl->DILocations);
}
+const
+DILocation *DILocation::getMergedLocations(ArrayRef<const DILocation *> Locs) {
+ if (Locs.empty())
+ return nullptr;
+ if (Locs.size() == 1)
+ return Locs[0];
+ auto *Merged = Locs[0];
+ for (auto I = std::next(Locs.begin()), E = Locs.end(); I != E; ++I) {
+ Merged = getMergedLocation(Merged, *I);
+ if (Merged == nullptr)
+ break;
+ }
+ return Merged;
+}
+
const DILocation *DILocation::getMergedLocation(const DILocation *LocA,
const DILocation *LocB) {
if (!LocA || !LocB)
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index c21c1a9078a9..eac7a3c7b6b3 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -2065,11 +2065,11 @@ bool llvm::promoteLoopAccessesToScalars(
});
++NumPromoted;
- // Grab a debug location for the inserted loads/stores; given that the
- // inserted loads/stores have little relation to the original loads/stores,
- // this code just arbitrarily picks a location from one, since any debug
- // location is better than none.
- DebugLoc DL = LoopUses[0]->getDebugLoc();
+ // Look at all the loop uses, and try to merge their locations.
+ std::vector<const DILocation *> LoopUsesLocs;
+ for (auto U : LoopUses)
+ LoopUsesLocs.push_back(U->getDebugLoc().get());
+ auto DL = DebugLoc(DILocation::getMergedLocations(LoopUsesLocs));
// We use the SSAUpdater interface to insert phi nodes as required.
SmallVector<PHINode *, 16> NewPHIs;
diff --git a/llvm/test/Transforms/LICM/sink-debuginfo-preserve.ll b/llvm/test/Transforms/LICM/sink-debuginfo-preserve.ll
new file mode 100644
index 000000000000..9bb7edccf243
--- /dev/null
+++ b/llvm/test/Transforms/LICM/sink-debuginfo-preserve.ll
@@ -0,0 +1,147 @@
+; RUN: opt -S -licm < %s | FileCheck %s
+
+; LICM is trying to merge the two `store` in block %14 and %17, but given their
+; locations disagree, it sets a line zero location instead instead of picking a
+; random one (the DILocation picked the nearest enclosing scope of the two stores).
+
+; Original C testcase.
+; volatile int a;
+; extern int g;
+; int g;
+; void f1() {
+; while (a) {
+; g = 0;
+; if (a)
+; g = 0;
+; }
+; }
+
+; CHECK: %.lcssa = phi i32
+; CHECK-NEXT: store i32 %.lcssa, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @g_390, i64 0, i64 1), align 4, !dbg [[storeLocation:![0-9]+]]
+; CHECK: [[storeLocation]] = !DILocation(line: 0
+
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.15.0"
+
+ at b = global i32 0, align 4, !dbg !0
+ at c = global i32 0, align 4, !dbg !10
+ at g_390 = local_unnamed_addr global [2 x i32] zeroinitializer, align 4, !dbg !12
+ at a = local_unnamed_addr global i32 0, align 4, !dbg !6
+
+define i32 @main() local_unnamed_addr !dbg !22 {
+ %1 = load volatile i32, i32* @b, align 4, !dbg !37, !tbaa !40
+ %2 = icmp sgt i32 %1, -9, !dbg !44
+ br i1 %2, label %3, label %5, !dbg !45
+
+3: ; preds = %0
+ br label %9, !dbg !45
+
+4: ; preds = %9
+ br label %5, !dbg !45
+
+5: ; preds = %4, %0
+ %6 = load volatile i32, i32* @c, align 4, !dbg !46, !tbaa !40
+ %7 = icmp slt i32 %6, 6, !dbg !47
+ br i1 %7, label %8, label %24, !dbg !48
+
+8: ; preds = %5
+ br label %14, !dbg !48
+
+9: ; preds = %3, %9
+ %10 = load volatile i32, i32* @b, align 4, !dbg !49, !tbaa !40
+ %11 = add nsw i32 %10, -1, !dbg !49
+ store volatile i32 %11, i32* @b, align 4, !dbg !49, !tbaa !40
+ %12 = load volatile i32, i32* @b, align 4, !dbg !37, !tbaa !40
+ %13 = icmp sgt i32 %12, -9, !dbg !44
+ br i1 %13, label %9, label %4, !dbg !45, !llvm.loop !50
+
+14: ; preds = %8, %18
+ store i32 0, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @g_390, i64 0, i64 1), align 4, !dbg !53, !tbaa !40
+ %15 = load volatile i32, i32* @b, align 4, !dbg !54, !tbaa !40
+ %16 = icmp eq i32 %15, 0, !dbg !54
+ br i1 %16, label %17, label %18, !dbg !55
+
+17: ; preds = %14
+ store i32 0, i32* getelementptr inbounds ([2 x i32], [2 x i32]* @g_390, i64 0, i64 1), align 4, !dbg !56, !tbaa !40
+ br label %18
+
+18: ; preds = %14, %17
+ %19 = load volatile i32, i32* @c, align 4, !dbg !57, !tbaa !40
+ %20 = add nsw i32 %19, 1, !dbg !57
+ store volatile i32 %20, i32* @c, align 4, !dbg !57, !tbaa !40
+ %21 = load volatile i32, i32* @c, align 4, !dbg !46, !tbaa !40
+ %22 = icmp slt i32 %21, 6, !dbg !47
+ br i1 %22, label %14, label %23, !dbg !48, !llvm.loop !58
+
+23: ; preds = %18
+ br label %24, !dbg !48
+
+24: ; preds = %23, %5
+ ret i32 0, !dbg !60
+}
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!17, !18, !19, !20}
+!llvm.ident = !{!21}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "b", scope: !2, file: !3, line: 1, type: !8, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project d3588d0814c4cbc7fca677b4d9634f6e1428a331)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: None, sysroot: "/")
+!3 = !DIFile(filename: "a.c", directory: "/Users/davide/work/build/bin")
+!4 = !{}
+!5 = !{!6, !0, !10, !12}
+!6 = !DIGlobalVariableExpression(var: !7, expr: !DIExpression())
+!7 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !8, isLocal: false, isDefinition: true)
+!8 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !9)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DIGlobalVariableExpression(var: !11, expr: !DIExpression())
+!11 = distinct !DIGlobalVariable(name: "c", scope: !2, file: !3, line: 1, type: !8, isLocal: false, isDefinition: true)
+!12 = !DIGlobalVariableExpression(var: !13, expr: !DIExpression())
+!13 = distinct !DIGlobalVariable(name: "g_390", scope: !2, file: !3, line: 2, type: !14, isLocal: false, isDefinition: true)
+!14 = !DICompositeType(tag: DW_TAG_array_type, baseType: !9, size: 64, elements: !15)
+!15 = !{!16}
+!16 = !DISubrange(count: 2)
+!17 = !{i32 7, !"Dwarf Version", i32 4}
+!18 = !{i32 2, !"Debug Info Version", i32 3}
+!19 = !{i32 1, !"wchar_size", i32 4}
+!20 = !{i32 7, !"PIC Level", i32 2}
+!21 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project d3588d0814c4cbc7fca677b4d9634f6e1428a331)"}
+!22 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 3, type: !23, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !25)
+!23 = !DISubroutineType(types: !24)
+!24 = !{!9}
+!25 = !{!26}
+!26 = !DILocalVariable(name: "l_1546", scope: !27, file: !3, line: 11, type: !32)
+!27 = distinct !DILexicalBlock(scope: !28, file: !3, line: 10, column: 10)
+!28 = distinct !DILexicalBlock(scope: !29, file: !3, line: 8, column: 9)
+!29 = distinct !DILexicalBlock(scope: !30, file: !3, line: 6, column: 23)
+!30 = distinct !DILexicalBlock(scope: !31, file: !3, line: 6, column: 3)
+!31 = distinct !DILexicalBlock(scope: !22, file: !3, line: 6, column: 3)
+!32 = !DICompositeType(tag: DW_TAG_array_type, baseType: !33, size: 288, elements: !34)
+!33 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!34 = !{!35, !36, !35}
+!35 = !DISubrange(count: 3)
+!36 = !DISubrange(count: 4)
+!37 = !DILocation(line: 4, column: 10, scope: !38)
+!38 = distinct !DILexicalBlock(scope: !39, file: !3, line: 4, column: 3)
+!39 = distinct !DILexicalBlock(scope: !22, file: !3, line: 4, column: 3)
+!40 = !{!41, !41, i64 0}
+!41 = !{!"int", !42, i64 0}
+!42 = !{!"omnipotent char", !43, i64 0}
+!43 = !{!"Simple C/C++ TBAA"}
+!44 = !DILocation(line: 4, column: 12, scope: !38)
+!45 = !DILocation(line: 4, column: 3, scope: !39)
+!46 = !DILocation(line: 6, column: 10, scope: !30)
+!47 = !DILocation(line: 6, column: 12, scope: !30)
+!48 = !DILocation(line: 6, column: 3, scope: !31)
+!49 = !DILocation(line: 4, column: 19, scope: !38)
+!50 = distinct !{!50, !45, !51, !52}
+!51 = !DILocation(line: 5, column: 5, scope: !39)
+!52 = !{!"llvm.loop.unroll.disable"}
+!53 = !DILocation(line: 7, column: 14, scope: !29)
+!54 = !DILocation(line: 8, column: 9, scope: !28)
+!55 = !DILocation(line: 8, column: 9, scope: !29)
+!56 = !DILocation(line: 12, column: 16, scope: !27)
+!57 = !DILocation(line: 6, column: 19, scope: !30)
+!58 = distinct !{!58, !48, !59, !52}
+!59 = !DILocation(line: 14, column: 3, scope: !31)
+!60 = !DILocation(line: 15, column: 1, scope: !22)
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