[llvm] 2cde0e2 - Revert "[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)"

Jorge Gorbe Moya via llvm-commits llvm-commits at lists.llvm.org
Fri May 3 13:06:14 PDT 2024


Author: Jorge Gorbe Moya
Date: 2024-05-03T13:05:08-07:00
New Revision: 2cde0e2f9779bf755ee9fd97e497bc948296c0c7

URL: https://github.com/llvm/llvm-project/commit/2cde0e2f9779bf755ee9fd97e497bc948296c0c7
DIFF: https://github.com/llvm/llvm-project/commit/2cde0e2f9779bf755ee9fd97e497bc948296c0c7.diff

LOG: Revert "[BasicBlockUtils] Remove redundant llvm.dbg instructions after blocks to reduce compile time (#89069)"

This reverts commit 2e3e0868748635b779ba89a772eae3664bd822e4. It caused
quadratic slowdown at compilation time in some cases. See the comments
in the original PR: https://github.com/llvm/llvm-project/pull/89069

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
    llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
    llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll

Removed: 
    llvm/test/Transforms/LoopUnroll/unroll-remove-redundant-dbg.ll


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
index 51fc28ef90ef6b..b9ed077b660dd1 100644
--- a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
+++ b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -333,10 +333,6 @@ bool llvm::MergeBlockIntoPredecessor(BasicBlock *BB, DomTreeUpdater *DTU,
   // Finally, erase the old block and update dominator info.
   DeleteDeadBlock(BB, DTU);
 
-  // Remove redundant "llvm.dbg" instrunctions after blocks have been merged.
-  if (PredBB->getParent()->getSubprogram())
-    RemoveRedundantDbgInstrs(PredBB);
-
   return true;
 }
 

diff  --git a/llvm/test/Transforms/LoopUnroll/unroll-remove-redundant-dbg.ll b/llvm/test/Transforms/LoopUnroll/unroll-remove-redundant-dbg.ll
deleted file mode 100644
index 66cd4d45444360..00000000000000
--- a/llvm/test/Transforms/LoopUnroll/unroll-remove-redundant-dbg.ll
+++ /dev/null
@@ -1,45 +0,0 @@
-; RUN: opt < %s -S -passes=loop-unroll | FileCheck %s
-
-define i64 @d(i1 %tobool.not, i32 %add, i64 %conv23) !dbg !14{
-entry:
-  br label %for.body
-
-for.body:                                         ; preds = %for.body, %entry
-  ; There should be only one "llvm.dbg.vale" after loop unrolling
-  ; CHECK: call void @llvm.dbg.value
-  ; CHECK-NOT: call void @llvm.dbg.value
-
-  %k.045 = phi i64 [ 0, %entry ], [ %k.046, %for.body ]
-  tail call void @llvm.dbg.value(metadata i32 0, metadata !13, metadata !DIExpression()), !dbg !17
-  %k.046 = add nuw nsw i64 %k.045, 1
-  %exitcond = icmp ne i64 %k.046, 5
-  br i1 %exitcond, label %for.body, label %for.end22
-
-for.end22:                                        ; preds = %for.body
-  ret i64 %k.046
-}
-
-; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
-declare void @llvm.dbg.value(metadata, metadata, metadata)
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!12}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C89, file: !1, producer: "clang version 19.0.0git (https://github.com/llvm/llvm-project.git ec062f5b33ed22c61742e3c1486f6cba915801e0)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
-!1 = !DIFile(filename: "unroll-remove-redundant-dbg.c", directory: "", checksumkind: CSK_MD5, checksum: "aa30a1d8c04deb9b0f3885c258d2b674")
-!2 = !{!3, !8, !10}
-!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
-!4 = distinct !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true)
-!5 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint32_t", file: !6, line: 198, baseType: !7)
-!6 = !DIFile(filename: "/usr/include/stdint.h", directory: "", checksumkind: CSK_MD5, checksum: "da031bcff2d0c1d65aa92e7e68a44ef3")
-!7 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
-!8 = !DIGlobalVariableExpression(var: !9, expr: !DIExpression())
-!9 = distinct !DIGlobalVariable(name: "c", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true)
-!10 = !DIGlobalVariableExpression(var: !11, expr: !DIExpression())
-!11 = distinct !DIGlobalVariable(name: "b", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true)
-!12 = !{i32 2, !"Debug Info Version", i32 3}
-!13 = !DILocalVariable(name: "f", scope: !14, file: !1, line: 4, type: !5)
-!14 = distinct !DISubprogram(name: "d", scope: !1, file: !1, line: 3, type: !15, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !16)
-!15 = !DISubroutineType(types: !16)
-!16 = !{}
-!17 = !DILocation(line: 0, scope: !14)

diff  --git a/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll b/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
index 5af73e789f11ce..e00d1daf71de58 100644
--- a/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
+++ b/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue-inlined.ll
@@ -9,6 +9,7 @@ init:
 
 ; CHECK:  %vala = load i64, ptr %ptr
 ; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD:![0-9]*]]
+; CHECK-NEXT:  call void @llvm.dbg.value(metadata i64 %vala, metadata [[MD]]
 ; CHECK-NEXT:  %valbmasked = and i64 %vala, 1
 
 a:                                              ; preds = %init

diff  --git a/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll b/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll
index c5d723c4e3dd61..af7da45ec089cc 100644
--- a/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll
+++ b/llvm/test/Transforms/SimplifyCFG/hoist-dbgvalue.ll
@@ -47,6 +47,7 @@ define i1 @hoist_with_debug2(i32 %x) !dbg !22 {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TOBOOL_NOT:%.*]] = icmp ugt i32 [[X:%.*]], 2
 ; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 [[X]], metadata [[META21:![0-9]+]], metadata !DIExpression()), !dbg [[DBG23:![0-9]+]]
+; CHECK-NEXT:    call void @llvm.dbg.value(metadata i32 [[X]], metadata [[META21]], metadata !DIExpression()), !dbg [[DBG23]]
 ; CHECK-NEXT:    [[DOT:%.*]] = select i1 [[TOBOOL_NOT]], i1 false, i1 true
 ; CHECK-NEXT:    ret i1 [[DOT]]
 ;


        


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