[PATCH] D100371: [debug-info] SCCP should preserve the debug location for an one-to-one instruction replacement

[Yuanbo Li via Phabricator via llvm-commits]

yuanboli233 updated this revision to Diff 337233.
yuanboli233 added a comment.

Thanks for the suggestion, @Orlando.

One way to check whether the debug location is preserved or not is to keep one of the llvm.dbg.value call which has the same debug location with the replaced instruction. So I keep one of the llvm.dbg.value call in the updated test case.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100371/new/

https://reviews.llvm.org/D100371

Files:
  llvm/lib/Transforms/Scalar/SCCP.cpp
  llvm/test/Transforms/SCCP/sccp_preserve_debugloc.ll


Index: llvm/test/Transforms/SCCP/sccp_preserve_debugloc.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SCCP/sccp_preserve_debugloc.ll
@@ -0,0 +1,73 @@
+; RUN: opt -sccp -S < %s | FileCheck %s
+; COM: Check whether the debug location is preserved.
+; CHECK: %{{[a-zA-Z0-9_]*}} = zext i32 %tmp9 to i64, !dbg ![[DBGLOC:[0-9]+]]
+; CHECK-NEXT: call void @llvm.dbg.value(metadata i64 %{{[0-9]+}}, metadata !{{[0-9]+}}, metadata !DIExpression()), !dbg ![[DBGLOC]]
+source_filename = "abc.ll"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foo(i64* %arg) !dbg !6 {
+bb:
+  %tmp = zext i8 undef to i32, !dbg !20
+  %tmp1 = getelementptr inbounds i64, i64* %arg, i32 0, !dbg !21
+  %tmp2 = load i64, i64* %tmp1, align 8, !dbg !22
+  switch i32 %tmp, label %bb20 [
+    i32 1, label %bb3
+    i32 2, label %bb4
+    i32 4, label %bb19
+  ], !dbg !23
+
+bb3:                                              ; preds = %bb
+  unreachable, !dbg !24
+
+bb4:                                              ; preds = %bb
+  %tmp5 = add i64 %tmp2, 3, !dbg !25
+  %tmp6 = and i64 %tmp5, 3, !dbg !26
+  %tmp7 = sub i64 3, %tmp6, !dbg !27
+  %tmp8 = shl i64 %tmp7, 1, !dbg !28
+  %tmp9 = trunc i64 %tmp8 to i32, !dbg !29
+  %tmp10 = sext i32 %tmp9 to i64, !dbg !30
+  call void @llvm.dbg.value(metadata i64 %tmp10, metadata !19, metadata !DIExpression()), !dbg !30
+  unreachable, !dbg !31
+
+bb19:                                             ; preds = %bb
+  unreachable, !dbg !32
+
+bb20:                                             ; preds = %bb
+  ret void, !dbg !33
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #0
+
+attributes #0 = { nofree nosync nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!3, !4}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "abc_simp.ll", directory: "/")
+!2 = !{}
+!3 = !{i32 14}
+!4 = !{i32 9}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!19}
+!10 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!12 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!19 = !DILocalVariable(name: "9", scope: !6, file: !1, line: 11, type: !12)
+!20 = !DILocation(line: 1, column: 1, scope: !6)
+!21 = !DILocation(line: 2, column: 1, scope: !6)
+!22 = !DILocation(line: 3, column: 1, scope: !6)
+!23 = !DILocation(line: 4, column: 1, scope: !6)
+!24 = !DILocation(line: 5, column: 1, scope: !6)
+!25 = !DILocation(line: 6, column: 1, scope: !6)
+!26 = !DILocation(line: 7, column: 1, scope: !6)
+!27 = !DILocation(line: 8, column: 1, scope: !6)
+!28 = !DILocation(line: 9, column: 1, scope: !6)
+!29 = !DILocation(line: 10, column: 1, scope: !6)
+!30 = !DILocation(line: 11, column: 1, scope: !6)
+!31 = !DILocation(line: 12, column: 1, scope: !6)
+!32 = !DILocation(line: 13, column: 1, scope: !6)
+!33 = !DILocation(line: 14, column: 1, scope: !6)
Index: llvm/lib/Transforms/Scalar/SCCP.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/SCCP.cpp
+++ llvm/lib/Transforms/Scalar/SCCP.cpp
@@ -1693,6 +1693,7 @@
         continue;
       if (IV.getConstantRange().isAllNonNegative()) {
         auto *ZExt = new ZExtInst(ExtOp, Inst.getType(), "", &Inst);
+        ZExt->setDebugLoc(Inst.getDebugLoc());
         InsertedValues.insert(ZExt);
         Inst.replaceAllUsesWith(ZExt);
         Solver.removeLatticeValueFor(&Inst);


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