[llvm] r322083 - [EarlyCSE] Salvage debug info during DCE

[Petar Jovanovic via llvm-commits]

Author: petarj
Date: Tue Jan  9 07:08:37 2018
New Revision: 322083

URL: http://llvm.org/viewvc/llvm-project?rev=322083&view=rev
Log:
[EarlyCSE] Salvage debug info during DCE

EarlyCSE did not try to salvage debug info during erasing of instructions.
This change fixes it.

Patch by Djordje Todorovic.

Differential Revision: https://reviews.llvm.org/D41496

Added:
    llvm/trunk/test/Transforms/EarlyCSE/debuginfo-dce.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp?rev=322083&r1=322082&r2=322083&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/EarlyCSE.cpp Tue Jan  9 07:08:37 2018
@@ -717,6 +717,7 @@ bool EarlyCSE::processNode(DomTreeNode *
     // Dead instructions should just be removed.
     if (isInstructionTriviallyDead(Inst, &TLI)) {
       DEBUG(dbgs() << "EarlyCSE DCE: " << *Inst << '\n');
+      salvageDebugInfo(*Inst);
       removeMSSA(Inst);
       Inst->eraseFromParent();
       Changed = true;

Added: llvm/trunk/test/Transforms/EarlyCSE/debuginfo-dce.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/EarlyCSE/debuginfo-dce.ll?rev=322083&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/EarlyCSE/debuginfo-dce.ll (added)
+++ llvm/trunk/test/Transforms/EarlyCSE/debuginfo-dce.ll Tue Jan  9 07:08:37 2018
@@ -0,0 +1,64 @@
+; RUN: opt -early-cse -S %s -o - | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Function Attrs: nounwind uwtable
+define i32 @foo() !dbg !6 {
+entry:
+  %0 = call i64 @llvm.ctpop.i64(i64 0), !dbg !14
+  %1 = inttoptr i64 %0 to i32*, !dbg !14
+  call void @llvm.dbg.value(metadata i32* %1, i64 0, metadata !11, metadata !13), !dbg !14
+; CHECK: call void @llvm.dbg.value(metadata i64 0, metadata !11, metadata !DIExpression()), !dbg !13
+  %call = call i32* (...) @baa(), !dbg !15
+  %2 = ptrtoint i32* %call to i64, !dbg !16
+  %3 = inttoptr i64 %2 to i32*, !dbg !16
+  call void @llvm.dbg.value(metadata i32* %3, i64 0, metadata !11, metadata !13), !dbg !14
+  %tobool = icmp ne i32* %3, null, !dbg !17
+  br i1 %tobool, label %if.end, label %if.then, !dbg !19
+
+if.then:                                          ; preds = %entry
+  br label %cleanup, !dbg !20
+
+if.end:                                           ; preds = %entry
+  %4 = ptrtoint i32* %3 to i32, !dbg !21
+  br label %cleanup, !dbg !22
+
+cleanup:                                          ; preds = %if.end, %if.then
+  %retval.0 = phi i32 [ %4, %if.end ], [ 0, %if.then ]
+  ret i32 %retval.0, !dbg !22
+}
+
+declare i32* @baa(...)
+
+; Function Attrs: nounwind readnone
+declare i64 @llvm.ctpop.i64(i64)
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 6.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "test.c", directory: "/dir")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 6.0.0"}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !7, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0, variables: !10)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9}
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{!11}
+!11 = !DILocalVariable(name: "ptr", scope: !6, file: !1, line: 4, type: !12)
+!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 64)
+!13 = !DIExpression()
+!14 = !DILocation(line: 4, column: 8, scope: !6)
+!15 = !DILocation(line: 5, column: 9, scope: !6)
+!16 = !DILocation(line: 5, column: 7, scope: !6)
+!17 = !DILocation(line: 7, column: 7, scope: !18)
+!18 = distinct !DILexicalBlock(scope: !6, file: !1, line: 7, column: 6)
+!19 = !DILocation(line: 7, column: 6, scope: !6)
+!20 = !DILocation(line: 8, column: 5, scope: !18)
+!21 = !DILocation(line: 10, column: 10, scope: !6)
+!22 = !DILocation(line: 11, column: 1, scope: !6)