[llvm] 1f11d1b - [DebugInfo] Fix jump threading failing to update cloned dbg.values

Stephen Tozer via llvm-commits llvm-commits at lists.llvm.org
Mon Jan 9 03:43:03 PST 2023


Author: Ben Mudd
Date: 2023-01-09T11:42:33Z
New Revision: 1f11d1bd1261f8126b1d04faa9231cab87633e66

URL: https://github.com/llvm/llvm-project/commit/1f11d1bd1261f8126b1d04faa9231cab87633e66
DIFF: https://github.com/llvm/llvm-project/commit/1f11d1bd1261f8126b1d04faa9231cab87633e66.diff

LOG: [DebugInfo] Fix jump threading failing to update cloned dbg.values

This is a patch to fix duplicated dbg.values in the JumpThreading pass not
pointing towards their local value, and instead towards the variable in the
original block.
JumpThreadingPass::cloneInstructions is the changed function to target metadata
as well as normal cloned values.

Reviewed By: jmorse, StephenTozer

Differential Revision: https://reviews.llvm.org/D140006

Added: 
    llvm/test/Transforms/JumpThreading/thread-debug-info.ll

Modified: 
    llvm/lib/Transforms/Scalar/JumpThreading.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index f1d622a52e8c..19ed7e555dc5 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -2083,6 +2083,30 @@ JumpThreadingPass::cloneInstructions(BasicBlock::iterator BI,
   // block, evaluate them to account for entry from PredBB.
   DenseMap<Instruction *, Value *> ValueMapping;
 
+  // Retargets llvm.dbg.value to any renamed variables.
+  auto RetargetDbgValueIfPossible = [&](Instruction *NewInst) -> bool {
+    auto DbgInstruction = dyn_cast<DbgValueInst>(NewInst);
+    if (!DbgInstruction)
+      return false;
+
+    SmallSet<std::pair<Value *, Value *>, 16> OperandsToRemap;
+    for (auto DbgOperand : DbgInstruction->location_ops()) {
+      auto DbgOperandInstruction = dyn_cast<Instruction>(DbgOperand);
+      if (!DbgOperandInstruction)
+        continue;
+
+      auto I = ValueMapping.find(DbgOperandInstruction);
+      if (I != ValueMapping.end()) {
+        OperandsToRemap.insert(
+            std::pair<Value *, Value *>(DbgOperand, I->second));
+      }
+    }
+
+    for (auto &[OldOp, MappedOp] : OperandsToRemap)
+      DbgInstruction->replaceVariableLocationOp(OldOp, MappedOp);
+    return true;
+  };
+
   // Clone the phi nodes of the source basic block into NewBB.  The resulting
   // phi nodes are trivial since NewBB only has one predecessor, but SSAUpdater
   // might need to rewrite the operand of the cloned phi.
@@ -2111,6 +2135,9 @@ JumpThreadingPass::cloneInstructions(BasicBlock::iterator BI,
     ValueMapping[&*BI] = New;
     adaptNoAliasScopes(New, ClonedScopes, Context);
 
+    if (RetargetDbgValueIfPossible(New))
+      continue;
+
     // Remap operands to patch up intra-block references.
     for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
       if (Instruction *Inst = dyn_cast<Instruction>(New->getOperand(i))) {

diff  --git a/llvm/test/Transforms/JumpThreading/thread-debug-info.ll b/llvm/test/Transforms/JumpThreading/thread-debug-info.ll
new file mode 100644
index 000000000000..b85a8fb71950
--- /dev/null
+++ b/llvm/test/Transforms/JumpThreading/thread-debug-info.ll
@@ -0,0 +1,98 @@
+; RUN: opt -S -passes=jump-threading < %s | FileCheck %s
+
+ at a = global i32 0, align 4
+; Test that the llvm.dbg.value calls in a threaded block are correctly updated to
+; target the locals in their threaded block, and not the unthreaded one.
+define void @test2(i32 %cond1, i32 %cond2) {
+; CHECK: [[globalptr:@.*]] = global i32 0, align 4
+; CHECK: bb.cond2:
+; CHECK: call void @llvm.dbg.value(metadata ptr null, metadata ![[DBG1ptr:[0-9]+]], metadata !DIExpression()), !dbg ![[DBG2ptr:[0-9]+]]
+; CHECK-NEXT: [[TOBOOL1:%.*]] = icmp eq i32 %cond2, 0, !dbg ![[DBGLOCtobool1:[0-9]+]]
+; CHECK-NEXT: call void @llvm.dbg.value(metadata !DIArgList(ptr null, i1 [[TOBOOL1]], i1 [[TOBOOL1]]), metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 2, DW_OP_plus)), !dbg !{{[0-9]+}}
+; CHECK: bb.cond2.thread:
+; CHECK-NEXT: call void @llvm.dbg.value(metadata ptr [[globalptr]], metadata ![[DBG1ptr]], metadata !DIExpression()), !dbg ![[DBG2ptr]]
+; CHECK-NEXT: [[TOBOOL12:%.*]] = icmp eq i32 %cond2, 0, !dbg ![[DBGLOCtobool1]]
+; CHECK-NEXT: call void @llvm.dbg.value(metadata !DIArgList(ptr [[globalptr]], i1 [[TOBOOL12]], i1 [[TOBOOL12]]), metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 2, DW_OP_plus)), !dbg !{{[0-9]+}}
+entry:
+  %tobool = icmp eq i32 %cond1, 0, !dbg !15
+  call void @llvm.dbg.value(metadata i1 %tobool, metadata !9, metadata !DIExpression()), !dbg !15
+  br i1 %tobool, label %bb.cond2, label %bb.f1, !dbg !16
+
+bb.f1:                                            ; preds = %entry
+  call void @f1(), !dbg !17
+  br label %bb.cond2, !dbg !18
+
+bb.cond2:                                         ; preds = %bb.f1, %entry
+  %ptr = phi ptr [ null, %bb.f1 ], [ @a, %entry ], !dbg !19
+  call void @llvm.dbg.value(metadata ptr %ptr, metadata !11, metadata !DIExpression()), !dbg !19
+  %tobool1 = icmp eq i32 %cond2, 0, !dbg !20
+  call void @llvm.dbg.value(metadata !DIArgList(ptr %ptr, i1 %tobool1, i1 %tobool1), metadata !13, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 2, DW_OP_plus)), !dbg !20
+  br i1 %tobool1, label %bb.file, label %bb.f2, !dbg !21
+
+bb.f2:                                            ; preds = %bb.cond2
+  call void @f2(), !dbg !22
+  br label %exit, !dbg !23
+
+bb.file:                                          ; preds = %bb.cond2
+  %cmp = icmp eq ptr %ptr, null, !dbg !24
+  call void @llvm.dbg.value(metadata i1 %cmp, metadata !14, metadata !DIExpression()), !dbg !24
+  br i1 %cmp, label %bb.f4, label %bb.f3, !dbg !25
+
+bb.f3:                                            ; preds = %bb.file
+  br label %exit, !dbg !26
+
+bb.f4:                                            ; preds = %bb.file
+  call void @f4(), !dbg !27
+  br label %exit, !dbg !28
+
+exit:                                             ; preds = %bb.f4, %bb.f3, %bb.f2
+  ret void, !dbg !29
+}
+
+declare void @f1()
+
+declare void @f2()
+
+declare void @f3()
+
+declare void @f4()
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+declare void @llvm.dbg.value(metadata, metadata, metadata) #0
+
+attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!2, !3}
+!llvm.module.flags = !{!4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "/home/ben/Documents/llvm-project/llvm/test/Transforms/JumpThreading/thread-debug-info.ll", directory: "/")
+!2 = !{i32 15}
+!3 = !{i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "test2", linkageName: "test2", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !{!9, !11, !13, !14}
+!9 = !DILocalVariable(name: "1", scope: !5, file: !1, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !5, file: !1, line: 5, type: !12)
+!12 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!13 = !DILocalVariable(name: "3", scope: !5, file: !1, line: 6, type: !10)
+!14 = !DILocalVariable(name: "4", scope: !5, file: !1, line: 10, type: !10)
+!15 = !DILocation(line: 1, column: 1, scope: !5)
+!16 = !DILocation(line: 2, column: 1, scope: !5)
+!17 = !DILocation(line: 3, column: 1, scope: !5)
+!18 = !DILocation(line: 4, column: 1, scope: !5)
+!19 = !DILocation(line: 5, column: 1, scope: !5)
+!20 = !DILocation(line: 6, column: 1, scope: !5)
+!21 = !DILocation(line: 7, column: 1, scope: !5)
+!22 = !DILocation(line: 8, column: 1, scope: !5)
+!23 = !DILocation(line: 9, column: 1, scope: !5)
+!24 = !DILocation(line: 10, column: 1, scope: !5)
+!25 = !DILocation(line: 11, column: 1, scope: !5)
+!26 = !DILocation(line: 12, column: 1, scope: !5)
+!27 = !DILocation(line: 13, column: 1, scope: !5)
+!28 = !DILocation(line: 14, column: 1, scope: !5)
+!29 = !DILocation(line: 15, column: 1, scope: !5)
\ No newline at end of file


        


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