[llvm] f49ee00 - [DebugInfo][ConstraintElimination] Fix debug value loss in replacing comparisons with the speculated constants (#136839)
via llvm-commits
llvm-commits at lists.llvm.org
Mon May 5 06:09:01 PDT 2025
Author: Shan Huang
Date: 2025-05-05T21:08:58+08:00
New Revision: f49ee00ec47f596269639987f5ea8755a358ca16
URL: https://github.com/llvm/llvm-project/commit/f49ee00ec47f596269639987f5ea8755a358ca16
DIFF: https://github.com/llvm/llvm-project/commit/f49ee00ec47f596269639987f5ea8755a358ca16.diff
LOG: [DebugInfo][ConstraintElimination] Fix debug value loss in replacing comparisons with the speculated constants (#136839)
Fix #135736
Added:
llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant-2.ll
llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant.ll
Modified:
llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 152c44a962ee8..f2d6e268743eb 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -24,6 +24,7 @@
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
@@ -1457,8 +1458,29 @@ static bool checkAndReplaceCondition(
return ShouldReplace;
});
NumCondsRemoved++;
+
+ // Update the debug value records that satisfy the same condition used
+ // in replaceUsesWithIf.
+ SmallVector<DbgVariableIntrinsic *> DbgUsers;
+ SmallVector<DbgVariableRecord *> DVRUsers;
+ findDbgUsers(DbgUsers, Cmp, &DVRUsers);
+
+ for (auto *DVR : DVRUsers) {
+ auto *DTN = DT.getNode(DVR->getParent());
+ if (!DTN || DTN->getDFSNumIn() < NumIn || DTN->getDFSNumOut() > NumOut)
+ continue;
+
+ auto *MarkedI = DVR->getInstruction();
+ if (MarkedI->getParent() == ContextInst->getParent() &&
+ MarkedI->comesBefore(ContextInst))
+ continue;
+
+ DVR->replaceVariableLocationOp(Cmp, ConstantC);
+ }
+
if (Cmp->use_empty())
ToRemove.push_back(Cmp);
+
return Changed;
};
diff --git a/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant-2.ll b/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant-2.ll
new file mode 100644
index 0000000000000..5c70c8ee4cb78
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant-2.ll
@@ -0,0 +1,83 @@
+; RUN: opt < %s -passes=constraint-elimination -S | FileCheck %s
+
+; Check that checkAndReplaceCondition() salvages the debug value information after replacing
+; the conditions (`%c.1` and `%t.2` in this test) with the speculated constants (GitHub Issue
+; #135736).
+; In particular, the debug value record uses should not be replaced if they come before the
+; context instrtuction (e.g., `%t.2` in this example).
+
+declare void @llvm.assume(i1 noundef) #0
+
+declare void @may_unwind()
+
+declare void @use(i1)
+
+define i1 @assume_single_bb_conditions_after_assume(i8 %a, i8 %b, i1 %c) !dbg !5 {
+; CHECK-LABEL: define i1 @assume_single_bb_conditions_after_assume(
+; CHECK: [[CMP_1:%.*]] = icmp ule i8 [[ADD_1:%.*]], [[B:%.*]], !dbg [[DBG12:![0-9]+]]
+; CHECK-NEXT: [[C_1:%.*]] = icmp ule i8 [[ADD_1]], [[B]], !dbg [[DBG13:![0-9]+]]
+; CHECK-NEXT: #dbg_value(i1 [[C_1]], [[META9:![0-9]+]], !DIExpression(), [[META14:![0-9]+]])
+; CHECK-NEXT: call void @use(i1 [[C_1]]), !dbg [[DBG15:![0-9]+]]
+; CHECK-NEXT: #dbg_value(i1 [[C_1]], [[META9]], !DIExpression(), [[META14]])
+; CHECK-NEXT: call void @may_unwind(), !dbg [[DBG16:![0-9]+]]
+; CHECK-NEXT: #dbg_value(i1 [[C_1]], [[META9]], !DIExpression(), [[META14]])
+; CHECK-NEXT: call void @llvm.assume(i1 [[CMP_1]]), !dbg [[DBG17:![0-9]+]]
+; CHECK-NEXT: #dbg_value(i1 [[C_1]], [[META9]], !DIExpression(), [[META14]])
+; CHECK-NEXT: #dbg_value(i1 true, [[META9]], !DIExpression(), [[META14]])
+; CHECK-NEXT: [[RES_1:%.*]] = xor i1 true, true, !dbg [[DBG18:![0-9]+]]
+;
+ %add.1 = add nuw nsw i8 %a, 1, !dbg !11
+ %cmp.1 = icmp ule i8 %add.1, %b, !dbg !12
+ %c.1 = icmp ule i8 %add.1, %b, !dbg !13
+ #dbg_value(i1 %c.1, !9, !DIExpression(), !14)
+ call void @use(i1 %c.1), !dbg !15
+ #dbg_value(i1 %c.1, !9, !DIExpression(), !14)
+ call void @may_unwind(), !dbg !16
+ #dbg_value(i1 %c.1, !9, !DIExpression(), !14)
+ call void @llvm.assume(i1 %cmp.1), !dbg !17
+ #dbg_value(i1 %c.1, !9, !DIExpression(), !14)
+ %t.2 = icmp ule i8 %a, %b, !dbg !14
+ #dbg_value(i1 %c.1, !9, !DIExpression(), !14)
+ %res.1 = xor i1 %c.1, %t.2, !dbg !18
+ %add.2 = add nuw nsw i8 %a, 2, !dbg !19
+ %c.2 = icmp ule i8 %add.2, %b, !dbg !20
+ %res.2 = xor i1 %res.1, %c.2, !dbg !21
+ ret i1 %res.2, !dbg !22
+}
+
+attributes #0 = { nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: write) }
+
+!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: "/app/example.ll", directory: "/")
+!2 = !{i32 12}
+!3 = !{i32 8}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "assume_single_bb_conditions_after_assume", linkageName: "assume_single_bb_conditions_after_assume", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !{!9}
+!9 = !DILocalVariable(name: "4", scope: !5, file: !1, line: 7, type: !10)
+!10 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!11 = !DILocation(line: 1, column: 1, scope: !5)
+!12 = !DILocation(line: 2, column: 1, scope: !5)
+!13 = !DILocation(line: 3, column: 1, scope: !5)
+!14 = !DILocation(line: 7, column: 1, scope: !5)
+!15 = !DILocation(line: 4, column: 1, scope: !5)
+!16 = !DILocation(line: 5, column: 1, scope: !5)
+!17 = !DILocation(line: 6, column: 1, scope: !5)
+!18 = !DILocation(line: 8, column: 1, scope: !5)
+!19 = !DILocation(line: 9, column: 1, scope: !5)
+!20 = !DILocation(line: 10, column: 1, scope: !5)
+!21 = !DILocation(line: 11, column: 1, scope: !5)
+!22 = !DILocation(line: 12, column: 1, scope: !5)
+
+; CHECK: [[META9]] = !DILocalVariable(name: "4",
+; CHECK: [[DBG12]] = !DILocation(line: 2, column: 1,
+; CHECK: [[DBG13]] = !DILocation(line: 3, column: 1,
+; CHECK: [[META14]] = !DILocation(line: 7, column: 1,
+; CHECK: [[DBG18]] = !DILocation(line: 8, column: 1,
+;.
diff --git a/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant.ll b/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant.ll
new file mode 100644
index 0000000000000..5caa14b3b52b8
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/salvage-dbg-values-replaced-by-constant.ll
@@ -0,0 +1,64 @@
+; RUN: opt < %s -passes=constraint-elimination -S | FileCheck %s
+
+; Check that checkAndReplaceCondition() salvages the debug value information after replacing
+; the conditions (`%t.1` in this test) with the speculated constants (GitHub Issue #135736).
+; In particular, debug uses are replaced if the debug record is dominated by the condition fact.
+
+define i1 @test_and_ule(i4 %x, i4 %y, i4 %z) !dbg !5 {
+; CHECK-LABEL: define i1 @test_and_ule(
+; CHECK-SAME: i4 [[X:%.*]], i4 [[Y:%.*]], i4 [[Z:%.*]])
+; CHECK: [[T_1:%.*]] = icmp ule i4 [[X]], [[Z]], !dbg [[DBG13:![0-9]+]]
+;
+entry:
+ %c.1 = icmp ule i4 %x, %y, !dbg !11
+ %c.2 = icmp ule i4 %y, %z, !dbg !12
+ %t.1 = icmp ule i4 %x, %z, !dbg !13
+ %and = and i1 %c.1, %c.2, !dbg !14
+ br i1 %and, label %then, label %exit, !dbg !15
+
+; CHECK: [[THEN:.*]]:
+; CHECK-NEXT: #dbg_value(i1 true, [[META9:![0-9]+]], !DIExpression(), [[DBG13]])
+; CHECK-NEXT: [[R_1:%.*]] = xor i1 true, true, !dbg [[DBG16:![0-9]+]]
+then: ; preds = %entry
+ #dbg_value(i1 %t.1, !9, !DIExpression(), !13)
+ %r.1 = xor i1 %t.1, %t.1, !dbg !16
+ br label %exit
+
+; CHECK: [[EXIT:.*]]:
+; CHECK-NEXT: #dbg_value(i1 [[T_1]], [[META17:![0-9]+]], !DIExpression(), [[DBG13]])
+; CHECK-NEXT: ret i1 [[T_1]], !dbg [[DBG18:![0-9]+]]
+exit: ; preds = %bb1, %entry
+ #dbg_value(i1 %t.1, !17, !DIExpression(), !13)
+ ret i1 %t.1, !dbg !18
+}
+
+!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: "temp.ll", directory: "/")
+!2 = !{i32 20}
+!3 = !{i32 17}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "test_and_ule", linkageName: "test_and_ule", scope: null, file: !1, line: 1, type: !6, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!6 = !DISubroutineType(types: !7)
+!7 = !{}
+!8 = !{!9}
+!9 = !DILocalVariable(name: "4", scope: !5, file: !1, line: 5, type: !10)
+!10 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!11 = !DILocation(line: 1, column: 1, scope: !5)
+!12 = !DILocation(line: 2, column: 1, scope: !5)
+!13 = !DILocation(line: 5, column: 1, scope: !5)
+!14 = !DILocation(line: 3, column: 1, scope: !5)
+!15 = !DILocation(line: 4, column: 1, scope: !5)
+!16 = !DILocation(line: 7, column: 1, scope: !5)
+!17 = !DILocalVariable(name: "6", scope: !5, file: !1, line: 7, type: !10)
+!18 = !DILocation(line: 20, column: 1, scope: !5)
+
+; CHECK: [[META9]] = !DILocalVariable(name: "4",
+; CHECK: [[DBG13]] = !DILocation(line: 5, column: 1,
+; CHECK: [[DBG16]] = !DILocation(line: 7, column: 1,
+; CHECK: [[META17]] = !DILocalVariable(name: "6",
+; CHECK: [[DBG18]] = !DILocation(line: 20, column: 1,
+;.
More information about the llvm-commits
mailing list