[llvm] r348896 - [Debuginfo] Prevent CodeGenPrepare from dropping debuginfo references.
Wolfgang Pieb via llvm-commits
llvm-commits at lists.llvm.org
Tue Dec 11 13:13:54 PST 2018
Author: wolfgangp
Date: Tue Dec 11 13:13:53 2018
New Revision: 348896
URL: http://llvm.org/viewvc/llvm-project?rev=348896&view=rev
Log:
[Debuginfo] Prevent CodeGenPrepare from dropping debuginfo references.
This fixes PR39845. CodeGenPrepare employs a transactional model when
performing optimizations, i.e. it changes the IR to attempt an optimization
and rolls back the change when it finds the change inadequate. It is during
the rollback that references to locals were dropped from debug value
intrinsics. This patch reinstates debuginfo references during rollbacks.
Reviewers: aprantl, vsk
Differential Revision: https://reviews.llvm.org/D55396
Added:
llvm/trunk/test/DebugInfo/Generic/codegenprep-value.ll
Modified:
llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
Modified: llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp?rev=348896&r1=348895&r2=348896&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp (original)
+++ llvm/trunk/lib/CodeGen/CodeGenPrepare.cpp Tue Dec 11 13:13:53 2018
@@ -2362,6 +2362,8 @@ class TypePromotionTransaction {
/// Keep track of the original uses (pair Instruction, Index).
SmallVector<InstructionAndIdx, 4> OriginalUses;
+ /// Keep track of the debug users.
+ SmallVector<DbgValueInst *, 1> DbgValues;
using use_iterator = SmallVectorImpl<InstructionAndIdx>::iterator;
@@ -2375,6 +2377,10 @@ class TypePromotionTransaction {
Instruction *UserI = cast<Instruction>(U.getUser());
OriginalUses.push_back(InstructionAndIdx(UserI, U.getOperandNo()));
}
+ // Record the debug uses separately. They are not in the instruction's
+ // use list, but they are replaced by RAUW.
+ findDbgValues(DbgValues, Inst);
+
// Now, we can replace the uses.
Inst->replaceAllUsesWith(New);
}
@@ -2387,6 +2393,15 @@ class TypePromotionTransaction {
UseIt != EndIt; ++UseIt) {
UseIt->Inst->setOperand(UseIt->Idx, Inst);
}
+ // RAUW has replaced all original uses with references to the new value,
+ // including the debug uses. Since we are undoing the replacements,
+ // the original debug uses must also be reinstated to maintain the
+ // correctness and utility of debug value instructions.
+ for (auto *DVI: DbgValues) {
+ LLVMContext &Ctx = Inst->getType()->getContext();
+ auto *MV = MetadataAsValue::get(Ctx, ValueAsMetadata::get(Inst));
+ DVI->setOperand(0, MV);
+ }
}
};
Added: llvm/trunk/test/DebugInfo/Generic/codegenprep-value.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/Generic/codegenprep-value.ll?rev=348896&view=auto
==============================================================================
--- llvm/trunk/test/DebugInfo/Generic/codegenprep-value.ll (added)
+++ llvm/trunk/test/DebugInfo/Generic/codegenprep-value.ll Tue Dec 11 13:13:53 2018
@@ -0,0 +1,75 @@
+; RUN: opt -codegenprepare -S %s | FileCheck %s
+;
+; Generated from the following source with:
+; clang -O2 -g -S -emit-llvm -mllvm -stop-after=indirectbr-expand test.cpp
+;
+; extern void use(int);
+; extern int foo(long long);
+;
+; void test(int p)
+; {
+; int i = p + 4;
+; (void)foo(i); // sign extension of i
+; if (p)
+; return;
+; use(i); // use of original i
+; }
+;
+; PR39845: Check that CodeGenPrepare does not drop the reference to a local when it is
+; sign-extended and used later.
+;
+; CHECK: define{{.*}}test
+; CHECK: call{{.*}}dbg.value(metadata i32 %p
+; CHECK: call{{.*}}dbg.value(metadata i32 %add
+;
+define dso_local void @_Z4testi(i32 %p) local_unnamed_addr !dbg !7 {
+entry:
+ call void @llvm.dbg.value(metadata i32 %p, metadata !12, metadata !DIExpression()), !dbg !14
+ %add = add nsw i32 %p, 4, !dbg !15
+ call void @llvm.dbg.value(metadata i32 %add, metadata !13, metadata !DIExpression()), !dbg !16
+ %conv = sext i32 %add to i64, !dbg !17
+ %call = tail call i32 @_Z3foox(i64 %conv), !dbg !18
+ %tobool = icmp eq i32 %p, 0, !dbg !19
+ br i1 %tobool, label %if.end, label %cleanup, !dbg !21
+
+if.end:
+ tail call void @_Z3usei(i32 %add), !dbg !22
+ br label %cleanup, !dbg !23
+
+cleanup:
+ ret void, !dbg !23
+}
+
+declare dso_local i32 @_Z3foox(i64) local_unnamed_addr
+declare dso_local void @_Z3usei(i32) local_unnamed_addr
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 348209)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/home/test/src")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 8.0.0 (trunk 348209)"}
+!7 = distinct !DISubprogram(name: "test", linkageName: "_Z4testi", scope: !1, file: !1, line: 4, type: !8, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !{!12, !13}
+!12 = !DILocalVariable(name: "p", arg: 1, scope: !7, file: !1, line: 4, type: !10)
+!13 = !DILocalVariable(name: "i", scope: !7, file: !1, line: 6, type: !10)
+!14 = !DILocation(line: 4, column: 15, scope: !7)
+!15 = !DILocation(line: 6, column: 13, scope: !7)
+!16 = !DILocation(line: 6, column: 7, scope: !7)
+!17 = !DILocation(line: 7, column: 13, scope: !7)
+!18 = !DILocation(line: 7, column: 9, scope: !7)
+!19 = !DILocation(line: 8, column: 7, scope: !20)
+!20 = distinct !DILexicalBlock(scope: !7, file: !1, line: 8, column: 7)
+!21 = !DILocation(line: 8, column: 7, scope: !7)
+!22 = !DILocation(line: 10, column: 3, scope: !7)
+!23 = !DILocation(line: 11, column: 1, scope: !7)
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