[llvm] cc7803e - [LSR][DebugInfo] Don't unnecessarily drop DebugLocs

[Jeremy Morse via llvm-commits]

Author: Yuanbo Li
Date: 2021-04-26T13:14:42+01:00
New Revision: cc7803ee3f767412223c234586834976d257a521

URL: https://github.com/llvm/llvm-project/commit/cc7803ee3f767412223c234586834976d257a521
DIFF: https://github.com/llvm/llvm-project/commit/cc7803ee3f767412223c234586834976d257a521.diff

LOG: [LSR][DebugInfo] Don't unnecessarily drop DebugLocs

When transforming a loop terminating condition into a "max" comparison,
the DebugLoc from the old condition should be set on the newly created
comparison. They are the same operation, just optimized. Fixes PR48067.

Differential Revision: https://reviews.llvm.org/D98218

Added: 
    llvm/test/Transforms/LoopStrengthReduce/optimizemax_debugloc.ll

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

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index ad37ed8c8d2d..2fe733ef6c3a 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -2347,6 +2347,7 @@ ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {
     new ICmpInst(Cond, Pred, Cond->getOperand(0), NewRHS, "scmp");
 
   // Delete the max calculation instructions.
+  NewCond->setDebugLoc(Cond->getDebugLoc());
   Cond->replaceAllUsesWith(NewCond);
   CondUse->setUser(NewCond);
   Instruction *Cmp = cast<Instruction>(Sel->getOperand(0));

diff  --git a/llvm/test/Transforms/LoopStrengthReduce/optimizemax_debugloc.ll b/llvm/test/Transforms/LoopStrengthReduce/optimizemax_debugloc.ll
new file mode 100644
index 000000000000..d2d5550c3d68
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/optimizemax_debugloc.ll
@@ -0,0 +1,62 @@
+; RUN: opt < %s -loop-reduce -S 2>&1 | FileCheck %s
+;; This test case checks that whether the new icmp instruction preserves
+;; the debug location of the original instruction for %exitcond
+; CHECK: icmp uge i32 %indvar.next, %n, !dbg ![[DBGLOC:[0-9]+]]
+; CHECK: ![[DBGLOC]] = !DILocation(line: 6, column: 1, scope
+
+; ModuleID = 'simplified-dbg.bc'
+source_filename = "abc.ll"
+target datalayout = "n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+define void @foobar(i32 %n) !dbg !6 {
+bb.nph:
+  %cond = icmp eq i32 %n, 0, !dbg !16
+  call void @llvm.dbg.value(metadata i1 %cond, metadata !9, metadata !DIExpression()), !dbg !16
+  %umax = select i1 %cond, i32 1, i32 %n, !dbg !17
+  call void @llvm.dbg.value(metadata i32 %umax, metadata !11, metadata !DIExpression()), !dbg !17
+  br label %bb, !dbg !18
+
+bb:                                               ; preds = %bb, %bb.nph
+  %i.03 = phi i32 [ 0, %bb.nph ], [ %indvar.next, %bb ], !dbg !19
+  call void @llvm.dbg.value(metadata i32 %i.03, metadata !13, metadata !DIExpression()), !dbg !19
+  %indvar.next = add nuw nsw i32 %i.03, 1, !dbg !20
+  call void @llvm.dbg.value(metadata i32 %indvar.next, metadata !14, metadata !DIExpression()), !dbg !20
+  %exitcond = icmp eq i32 %indvar.next, %umax, !dbg !21
+  call void @llvm.dbg.value(metadata i1 %exitcond, metadata !15, metadata !DIExpression()), !dbg !21
+  br i1 %exitcond, label %return, label %bb, !dbg !22
+
+return:                                           ; preds = %bb
+  ret void, !dbg !23
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!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: "simplified.ll", directory: "/")
+!2 = !{}
+!3 = !{i32 8}
+!4 = !{i32 5}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foobar", linkageName: "foobar", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!9, !11, !13, !14, !15}
+!9 = !DILocalVariable(name: "1", scope: !6, file: !1, line: 1, type: !10)
+!10 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 2, type: !12)
+!12 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!13 = !DILocalVariable(name: "3", scope: !6, file: !1, line: 4, type: !12)
+!14 = !DILocalVariable(name: "4", scope: !6, file: !1, line: 5, type: !12)
+!15 = !DILocalVariable(name: "5", scope: !6, file: !1, line: 6, type: !10)
+!16 = !DILocation(line: 1, column: 1, scope: !6)
+!17 = !DILocation(line: 2, column: 1, scope: !6)
+!18 = !DILocation(line: 3, column: 1, scope: !6)
+!19 = !DILocation(line: 4, column: 1, scope: !6)
+!20 = !DILocation(line: 5, column: 1, scope: !6)
+!21 = !DILocation(line: 6, column: 1, scope: !6)
+!22 = !DILocation(line: 7, column: 1, scope: !6)
+!23 = !DILocation(line: 8, column: 1, scope: !6)