[llvm] [DebugInfo][SelectionDAG] Add debug info salvaging for TRUNC nodes (PR #66922)
Stephen Tozer via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 20 08:48:36 PDT 2023
https://github.com/SLTozer created https://github.com/llvm/llvm-project/pull/66922
This patch adds support for salvaging TRUNC nodes during SelectionDAG, fixing LLVM issue #63076:
https://github.com/llvm/llvm-project/issues/63076
>From 8c286ff53dc3393b07e73aa01aeddb9dfbb172fc Mon Sep 17 00:00:00 2001
From: Ben Mudd <Ben.Mudd at sony.com>
Date: Wed, 20 Sep 2023 16:21:32 +0100
Subject: [PATCH 1/2] [DebugInfo][SelectionDAG] Add debug info salvaging for
TRUNC nodes
This patch adds support for salvaging TRUNC nodes during SelectionDAG,
fixing LLVM issue #63076:
https://github.com/llvm/llvm-project/issues/63076
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 10 +++-
.../lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 36 ++++++++++++-
.../CodeGen/X86/selection-dag-salvagetrunc.ll | 52 +++++++++++++++++++
3 files changed, 95 insertions(+), 3 deletions(-)
create mode 100644 llvm/test/CodeGen/X86/selection-dag-salvagetrunc.ll
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 484a6231b7f65fe..48e5468245733e6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -15,6 +15,7 @@
//
//===----------------------------------------------------------------------===//
+#include "SDNodeDbgValue.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
@@ -50,6 +51,7 @@
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Metadata.h"
@@ -13444,8 +13446,12 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
N0.getScalarValueSizeInBits(),
std::min(Op.getScalarValueSizeInBits(),
VT.getScalarSizeInBits()));
- if (TruncatedBits.isSubsetOf(Known.Zero))
- return DAG.getZExtOrTrunc(Op, DL, VT);
+ if (TruncatedBits.isSubsetOf(Known.Zero)) {
+ SDValue ZExtOrTrunc = DAG.getZExtOrTrunc(Op, DL, VT);
+ DAG.salvageDebugInfo(*N0.getNode());
+
+ return ZExtOrTrunc;
+ }
}
// fold (zext (truncate x)) -> (and x, mask)
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 7fcd1f4f898911a..71402a02c8995d6 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -10761,7 +10761,7 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
switch (N.getOpcode()) {
default:
break;
- case ISD::ADD:
+ case ISD::ADD: {
SDValue N0 = N.getOperand(0);
SDValue N1 = N.getOperand(1);
if (!isa<ConstantSDNode>(N0) && isa<ConstantSDNode>(N1)) {
@@ -10802,6 +10802,40 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
N0.getNode()->dumprFull(this);
dbgs() << " into " << *DIExpr << '\n');
}
+ break;
+ }
+ case ISD::TRUNCATE: {
+ SDValue N0 = N.getOperand(0);
+ TypeSize FromSize = N0.getValueSizeInBits();
+ TypeSize ToSize = N.getValueSizeInBits(0);
+
+ DIExpression *DbgExpression = DV->getExpression();
+ auto ExtOps = DIExpression::getExtOps(FromSize, ToSize, false);
+ auto NewLocOps = DV->copyLocationOps();
+ bool Changed = false;
+ for (size_t i = 0; i < NewLocOps.size(); ++i) {
+ if (NewLocOps[i].getKind() != SDDbgOperand::SDNODE ||
+ NewLocOps[i].getSDNode() != &N)
+ continue;
+
+ NewLocOps[i] = SDDbgOperand::fromNode(N0.getNode(), N0.getResNo());
+ DbgExpression = DIExpression::appendOpsToArg(DbgExpression, ExtOps, i);
+ Changed = true;
+ }
+ assert(Changed && "Salvage target doesn't use N");
+
+ SDDbgValue *Clone =
+ getDbgValueList(DV->getVariable(), DbgExpression, NewLocOps,
+ DV->getAdditionalDependencies(), DV->isIndirect(),
+ DV->getDebugLoc(), DV->getOrder(), DV->isVariadic());
+
+ ClonedDVs.push_back(Clone);
+ DV->setIsInvalidated();
+ DV->setIsEmitted();
+ LLVM_DEBUG(dbgs() << "SALVAGE: Rewriting"; N0.getNode()->dumprFull(this);
+ dbgs() << " into " << *DbgExpression << '\n');
+ break;
+ }
}
}
diff --git a/llvm/test/CodeGen/X86/selection-dag-salvagetrunc.ll b/llvm/test/CodeGen/X86/selection-dag-salvagetrunc.ll
new file mode 100644
index 000000000000000..95d63577d0242c9
--- /dev/null
+++ b/llvm/test/CodeGen/X86/selection-dag-salvagetrunc.ll
@@ -0,0 +1,52 @@
+; RUN: llc --stop-after=finalize-isel < %s | FileCheck %s
+;
+; Verify that we can correctly salvage truncate expressions during SelectionDAG.
+; Fixes LLVM issue #63076.
+
+; CHECK: body
+; CHECK: DBG_INSTR_REF !{{[0-9]+}}, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_convert, 8, DW_ATE_unsigned, DW_OP_LLVM_convert, 1, DW_ATE_unsigned)
+
+source_filename = "repro.cpp"
+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-linux-gnu"
+
+define dso_local noundef i32 @_Z3funv() !dbg !10 {
+entry:
+ %call = tail call noundef zeroext i1 @_Z3getv(), !dbg !17
+ call void @llvm.dbg.value(metadata i1 %call, metadata !15, metadata !DIExpression()), !dbg !18
+ %conv = zext i1 %call to i32, !dbg !19
+ ret i32 %conv, !dbg !20
+}
+
+declare !dbg !21 noundef zeroext i1 @_Z3getv()
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 18.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "repro.cpp", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!9 = !{!"clang version 18.0.0"}
+!10 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 2, type: !11, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !14)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!13}
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !{!15}
+!15 = !DILocalVariable(name: "b", scope: !10, file: !1, line: 4, type: !16)
+!16 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!17 = !DILocation(line: 4, column: 11, scope: !10)
+!18 = !DILocation(line: 0, scope: !10)
+!19 = !DILocation(line: 5, column: 9, scope: !10)
+!20 = !DILocation(line: 5, column: 2, scope: !10)
+!21 = !DISubprogram(name: "get", linkageName: "_Z3getv", scope: !1, file: !1, line: 1, type: !22, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+!22 = !DISubroutineType(types: !23)
+!23 = !{!16}
>From 022a38b3b0c9e085488d6295546873f099109339 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <Stephen.Tozer at Sony.com>
Date: Wed, 20 Sep 2023 16:46:18 +0100
Subject: [PATCH 2/2] Remove unused includes
---
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 2 --
1 file changed, 2 deletions(-)
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 48e5468245733e6..d4c6abde70c7098 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -15,7 +15,6 @@
//
//===----------------------------------------------------------------------===//
-#include "SDNodeDbgValue.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/ArrayRef.h"
@@ -51,7 +50,6 @@
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/DataLayout.h"
-#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Metadata.h"
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