[llvm] [SelectionDAG] Salvage debug info for non-constant ADDs (PR #68981)
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Fri Oct 13 04:59:35 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-debuginfo
Author: David (dstenb)
<details>
<summary>Changes</summary>
Teach SelectionDAG::salvageDebugInfo() to salvage debug information for
ADD nodes where the RHS is non-constant.
Co-authored-by: Mikael Holmen <mikael.holmen@<!-- -->ericsson.com>
- [DebugInfo] Precommit testcase for pointer addition with unknown offset
- [SelectionDAG] Salvage debug info for non-constant ADDs
---
Full diff: https://github.com/llvm/llvm-project/pull/68981.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (+31-7)
- (added) llvm/test/DebugInfo/Sparc/pointer-add-unknown-offset-debug-info.mir (+60)
``````````diff
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e831316efff52ba..200123a376d8e98 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -27,6 +27,7 @@
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
+#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/ISDOpcodes.h"
@@ -10781,8 +10782,11 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
case ISD::ADD: {
SDValue N0 = N.getOperand(0);
SDValue N1 = N.getOperand(1);
- if (!isa<ConstantSDNode>(N0) && isa<ConstantSDNode>(N1)) {
- uint64_t Offset = N.getConstantOperandVal(1);
+ if (!isa<ConstantSDNode>(N0)) {
+ bool RHSConstant = isa<ConstantSDNode>(N1);
+ uint64_t Offset;
+ if (RHSConstant)
+ Offset = N.getConstantOperandVal(1);
// Rewrite an ADD constant node into a DIExpression. Since we are
// performing arithmetic to compute the variable's *value* in the
@@ -10791,7 +10795,8 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
auto *DIExpr = DV->getExpression();
auto NewLocOps = DV->copyLocationOps();
bool Changed = false;
- for (size_t i = 0; i < NewLocOps.size(); ++i) {
+ size_t OrigLocOpsSize = NewLocOps.size();
+ for (size_t i = 0; i < OrigLocOpsSize; ++i) {
// We're not given a ResNo to compare against because the whole
// node is going away. We know that any ISD::ADD only has one
// result, so we can assume any node match is using the result.
@@ -10799,19 +10804,38 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) {
NewLocOps[i].getSDNode() != &N)
continue;
NewLocOps[i] = SDDbgOperand::fromNode(N0.getNode(), N0.getResNo());
- SmallVector<uint64_t, 3> ExprOps;
- DIExpression::appendOffset(ExprOps, Offset);
- DIExpr = DIExpression::appendOpsToArg(DIExpr, ExprOps, i, true);
+ if (RHSConstant) {
+ SmallVector<uint64_t, 3> ExprOps;
+ DIExpression::appendOffset(ExprOps, Offset);
+ DIExpr = DIExpression::appendOpsToArg(DIExpr, ExprOps, i, true);
+ } else {
+ // Convert to a variadic expression (if not already).
+ // convertToVariadicExpression() returns a const pointer, so we use
+ // a temporary const variable here.
+ const auto *TmpDIExpr =
+ DIExpression::convertToVariadicExpression(DIExpr);
+ SmallVector<uint64_t, 3> ExprOps;
+ ExprOps.push_back(dwarf::DW_OP_LLVM_arg);
+ ExprOps.push_back(NewLocOps.size());
+ ExprOps.push_back(dwarf::DW_OP_plus);
+ SDDbgOperand RHS =
+ SDDbgOperand::fromNode(N1.getNode(), N1.getResNo());
+ NewLocOps.push_back(RHS);
+ DIExpr = DIExpression::appendOpsToArg(TmpDIExpr, ExprOps, i, true);
+ }
Changed = true;
}
(void)Changed;
assert(Changed && "Salvage target doesn't use N");
+ bool IsVariadic =
+ DV->isVariadic() || OrigLocOpsSize != NewLocOps.size();
+
auto AdditionalDependencies = DV->getAdditionalDependencies();
SDDbgValue *Clone = getDbgValueList(DV->getVariable(), DIExpr,
NewLocOps, AdditionalDependencies,
DV->isIndirect(), DV->getDebugLoc(),
- DV->getOrder(), DV->isVariadic());
+ DV->getOrder(), IsVariadic);
ClonedDVs.push_back(Clone);
DV->setIsInvalidated();
DV->setIsEmitted();
diff --git a/llvm/test/DebugInfo/Sparc/pointer-add-unknown-offset-debug-info.mir b/llvm/test/DebugInfo/Sparc/pointer-add-unknown-offset-debug-info.mir
new file mode 100644
index 000000000000000..a9eabf895f0e6ad
--- /dev/null
+++ b/llvm/test/DebugInfo/Sparc/pointer-add-unknown-offset-debug-info.mir
@@ -0,0 +1,60 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3
+# RUN: llc -mtriple=sparcv9 %s -start-before=sparc-isel -o - -stop-after=sparc-isel | FileCheck %s
+--- |
+ target datalayout = "E-m:e-i64:64-n32:64-S128"
+ target triple = "sparcv9"
+
+ define void @pointer_add_unknown_offset(ptr %base, i32 %offset) !dbg !7 {
+ entry:
+ %idx.ext = sext i32 %offset to i64
+ %add.ptr = getelementptr inbounds i32, ptr %base, i64 %idx.ext
+ call void @llvm.dbg.value(metadata ptr %add.ptr, metadata !13, metadata !DIExpression()), !dbg !16
+ call void @llvm.dbg.value(metadata ptr %add.ptr, metadata !14, metadata !DIExpression(DW_OP_plus_uconst, 3, DW_OP_stack_value)), !dbg !16
+ call void @llvm.dbg.value(metadata !DIArgList(ptr %add.ptr, ptr %add.ptr), metadata !15, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus)), !dbg !16
+ store i32 42, ptr %add.ptr, align 4
+ ret void
+ }
+
+ declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!2, !3, !4, !5}
+ !llvm.ident = !{!6}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "test.c", directory: "/tmp", checksumkind: CSK_MD5, checksum: "4321633e52cefeee6e307c697a82574f")
+ !2 = !{i32 7, !"Dwarf Version", i32 5}
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !4 = !{i32 1, !"wchar_size", i32 4}
+ !5 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+ !6 = !{!"clang"}
+ !7 = distinct !DISubprogram(name: "pointer_add_unknown_offset", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+ !8 = !DISubroutineType(types: !9)
+ !9 = !{null, !10, !11}
+ !10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)
+ !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !12 = !{!13, !14, !15}
+ !13 = !DILocalVariable(name: "p", scope: !7, file: !1, line: 2, type: !10)
+ !14 = !DILocalVariable(name: "q", scope: !7, file: !1, line: 2, type: !10)
+ !15 = !DILocalVariable(name: "r", scope: !7, file: !1, line: 2, type: !10)
+ !16 = !DILocation(line: 0, scope: !7)
+...
+---
+name: pointer_add_unknown_offset
+alignment: 4
+tracksRegLiveness: true
+body: |
+ ; CHECK-LABEL: name: pointer_add_unknown_offset
+ ; CHECK: bb.0.entry:
+ ; CHECK-NEXT: liveins: $i0, $i1
+ ; CHECK-NEXT: {{ $}}
+ ; CHECK-NEXT: [[COPY:%[0-9]+]]:i64regs = COPY $i1
+ ; CHECK-NEXT: [[COPY1:%[0-9]+]]:i64regs = COPY $i0
+ ; CHECK-NEXT: [[SRAri:%[0-9]+]]:i64regs = SRAri [[COPY]], 0
+ ; CHECK-NEXT: [[SLLXri:%[0-9]+]]:i64regs = SLLXri killed [[SRAri]], 2
+ ; CHECK-NEXT: DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value), [[COPY1]], [[SLLXri]], debug-location !16
+ ; CHECK-NEXT: DBG_VALUE_LIST !14, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_plus_uconst, 3, DW_OP_stack_value), [[COPY1]], [[SLLXri]], debug-location !16
+ ; CHECK-NEXT: DBG_VALUE_LIST !15, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 2, DW_OP_plus, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 3, DW_OP_plus, DW_OP_plus, DW_OP_stack_value), [[COPY1]], [[COPY1]], [[SLLXri]], [[SLLXri]], debug-location !16
+ ; CHECK-NEXT: [[ORri:%[0-9]+]]:intregs = ORri $g0, 42
+ ; CHECK-NEXT: STrr [[COPY1]], killed [[SLLXri]], killed [[ORri]] :: (store (s32) into %ir.add.ptr)
+ ; CHECK-NEXT: RETL 8
``````````
</details>
https://github.com/llvm/llvm-project/pull/68981
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