Revert "[DebugInfo][Dexter] Unreachable line stepped onto after SimplifyCFG."

This reverts commit r344120.

It was causing buildbot failures.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344135 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/Utils/Local.h

@@ -446,15 +446,6 @@ void copyRangeMetadata(const DataLayout &DL, const LoadInst &OldLI, MDNode *N,
 /// Remove the debug intrinsic instructions for the given instruction.
 void dropDebugUsers(Instruction &I);
 
-/// Hoist all of the instructions in the \p IfBlock to the dominant block
-/// \p DomBlock, by moving its instructions to the insertion point \p InsertPt.
-///
-/// The moved instructions receive the insertion point debug location values
-/// (DILocations) and their debug intrinsic instructions (dbg.values) are
-/// removed.
-void hoistAllInstructionsInto(BasicBlock *DomBlock,Instruction *InsertPt,
-                              BasicBlock *IfBlock);
-
 //===----------------------------------------------------------------------===//
 //  Intrinsic pattern matching
 //

lib/Transforms/Utils/Local.cpp

@@ -2529,34 +2529,6 @@ void llvm::dropDebugUsers(Instruction &I) {
     DII->eraseFromParent();
 }
 
-void llvm::hoistAllInstructionsInto(BasicBlock *DomBlock,Instruction *InsertPt,
-                                    BasicBlock *IfBlock) {
-  // Since we are moving the instructions out of its basic block, we do not
-  // retain their original debug locations (DILocations) and debug intrinsic
-  // instructions (dbg.values).
-  //
-  // Doing so would degrade the debugging experience and adversely affect the
-  // accuracy of profiling information.
-  //
-  // Currently, when hoisting the instructions, we take the following actions:
-  // - Remove their dbg.values.
-  // - Set their debug locations to the values from the insertion point.
-  //
-  // See PR38762 for more details.
-  //
-  // TODO: Extend llvm.dbg.value to take more than one SSA Value (PR39141) to
-  // encode predicated DIExpressions that yield different results on different
-  // code paths.
-  for (auto &I : *IfBlock) {
-    I.dropUnknownNonDebugMetadata();
-    dropDebugUsers(I);
-    I.setDebugLoc(InsertPt->getDebugLoc());
-  }
-  DomBlock->getInstList().splice(InsertPt->getIterator(),
-                                 IfBlock->getInstList(), IfBlock->begin(),
-                                 IfBlock->getTerminator()->getIterator());
-}
-
 namespace {
 
 /// A potential constituent of a bitreverse or bswap expression. See

lib/Transforms/Utils/SimplifyCFG.cpp

@@ -2375,10 +2375,24 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
 
   // Move all 'aggressive' instructions, which are defined in the
   // conditional parts of the if's up to the dominating block.
-  if (IfBlock1)
-    hoistAllInstructionsInto(DomBlock, InsertPt, IfBlock1);
-  if (IfBlock2)
-    hoistAllInstructionsInto(DomBlock, InsertPt, IfBlock2);
+  if (IfBlock1) {
+    for (auto &I : *IfBlock1) {
+      I.dropUnknownNonDebugMetadata();
+      dropDebugUsers(I);
+    }
+    DomBlock->getInstList().splice(InsertPt->getIterator(),
+                                   IfBlock1->getInstList(), IfBlock1->begin(),
+                                   IfBlock1->getTerminator()->getIterator());
+  }
+  if (IfBlock2) {
+    for (auto &I : *IfBlock2) {
+      I.dropUnknownNonDebugMetadata();
+      dropDebugUsers(I);
+    }
+    DomBlock->getInstList().splice(InsertPt->getIterator(),
+                                   IfBlock2->getInstList(), IfBlock2->begin(),
+                                   IfBlock2->getTerminator()->getIterator());
+  }
 
   while (PHINode *PN = dyn_cast<PHINode>(BB->begin())) {
     // Change the PHI node into a select instruction.

test/CodeGen/X86/pr38762.ll

@@ -1,101 +0,0 @@
-; RUN: opt < %s -S -simplifycfg | FileCheck %s
-
-; Note: This patch is a complement to pr38763.
-;
-; When SimplifyCFG changes the PHI node into a select instruction, the debug
-; information becomes ambiguous. It causes the debugger to display unreached
-; lines and invalid variable values.
-;
-; When in the debugger, on the line "if (read1 > 3)", and we step from the
-; 'if' condition, onto the addition, then back to the 'if' again, which is
-; misleading because that addition doesn't really "happen" (it's speculated).
-
-; IR generated with:
-; clang -S -g -gno-column-info -O2 -emit-llvm pr38762.cpp -o pr38762.ll -mllvm -opt-bisect-limit=10
-
-; // pr38762.cpp
-; int main() {
-;   volatile int foo = 0;
-;   int read1 = foo;
-;   int brains = foo;
-; 
-;   if (read1 > 3) {
-;     brains *= 2;
-;     brains += 1;
-;   }
-; 
-;   return brains;
-; }
-
-; Change the debug locations associated with the PHI nodes being promoted, to
-; the debug locations from the insertion point in the dominant block.
-
-; CHECK-LABEL: entry
-; CHECK:  %cmp = icmp sgt i32 %foo.0., 3, !dbg !14
-; CHECK:  %mul = shl nsw i32 %foo.0.5, 1, !dbg !16
-; CHECK-NOT:  call void @llvm.dbg.value(metadata i32 %mul, metadata !15, metadata !DIExpression()), !dbg !25
-; CHECK:  %add = or i32 %mul, 1, !dbg !16
-; CHECK-NOT:  call void @llvm.dbg.value(metadata i32 %add, metadata !15, metadata !DIExpression()), !dbg !25
-; CHECK:  %brains.0 = select i1 %cmp, i32 %add, i32 %foo.0.5, !dbg !16
-
-; ModuleID = 'pr38762.cpp'
-source_filename = "pr38762.cpp"
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-linux-gnu"
-
-; Function Attrs: norecurse nounwind uwtable
-define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
-entry:
-  %foo = alloca i32, align 4
-  %foo.0..sroa_cast = bitcast i32* %foo to i8*
-  store volatile i32 0, i32* %foo, align 4
-  %foo.0. = load volatile i32, i32* %foo, align 4
-  %foo.0.5 = load volatile i32, i32* %foo, align 4
-  call void @llvm.dbg.value(metadata i32 %foo.0.5, metadata !15, metadata !DIExpression()), !dbg !25
-  %cmp = icmp sgt i32 %foo.0., 3, !dbg !26
-  br i1 %cmp, label %if.then, label %if.end, !dbg !28
-
-if.then:                                          ; preds = %entry
-  %mul = shl nsw i32 %foo.0.5, 1, !dbg !29
-  call void @llvm.dbg.value(metadata i32 %mul, metadata !15, metadata !DIExpression()), !dbg !25
-  %add = or i32 %mul, 1, !dbg !31
-  call void @llvm.dbg.value(metadata i32 %add, metadata !15, metadata !DIExpression()), !dbg !25
-  br label %if.end, !dbg !32
-
-if.end:                                           ; preds = %if.then, %entry
-  %brains.0 = phi i32 [ %add, %if.then ], [ %foo.0.5, %entry ], !dbg !33
-  call void @llvm.dbg.value(metadata i32 %brains.0, metadata !15, metadata !DIExpression()), !dbg !25
-  ret i32 %brains.0, !dbg !35
-}
-
-declare void @llvm.dbg.value(metadata, metadata, metadata) #2
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4, !5}
-!llvm.ident = !{!6}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 343753)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
-!1 = !DIFile(filename: "pr38762.cpp", directory: ".")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{i32 1, !"wchar_size", i32 4}
-!6 = !{!"clang version 8.0.0 (trunk 343753)"}
-!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
-!8 = !DISubroutineType(types: !9)
-!9 = !{!10}
-!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!11 = !{!15}
-!13 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !10)
-!15 = !DILocalVariable(name: "brains", scope: !7, file: !1, line: 4, type: !10)
-!25 = !DILocation(line: 4, scope: !7)
-!26 = !DILocation(line: 6, scope: !27)
-!27 = distinct !DILexicalBlock(scope: !7, file: !1, line: 6)
-!28 = !DILocation(line: 6, scope: !7)
-!29 = !DILocation(line: 7, scope: !30)
-!30 = distinct !DILexicalBlock(scope: !27, file: !1, line: 6)
-!31 = !DILocation(line: 8, scope: !30)
-!32 = !DILocation(line: 9, scope: !30)
-!33 = !DILocation(line: 0, scope: !7)
-!34 = !DILocation(line: 12, scope: !7)
-!35 = !DILocation(line: 11, scope: !7)

test/CodeGen/X86/pr38763.ll

@@ -30,13 +30,13 @@
 ; branches, as they becomes ambiguous.
 
 ; CHECK-LABEL: entry
-; CHECK:  %cmp = icmp eq i32 %foo.0., 4, !dbg !14
-; CHECK:  %add = add nsw i32 %foo.0.4, 2, !dbg !16
+; CHECK:  %cmp = icmp eq i32 %foo.0., 4
+; CHECK:  %add = add nsw i32 %foo.0.4, 2, !dbg !18
 ; CHECK-NOT: @llvm.dbg.value(metadata i32 %add
-; CHECK:  %sub = add nsw i32 %foo.0.4, -2, !dbg !16
+; CHECK:  %sub = add nsw i32 %foo.0.4, -2, !dbg !21
 ; CHECK-NOT: @llvm.dbg.value(metadata i32 %sub
 ; CHECK:  %result.0 = select i1 %cmp, i32 %add, i32 %sub
-; CHECK:  call void @llvm.dbg.value(metadata i32 %result.0, metadata !12, metadata !DIExpression()), !dbg !13
+; CHECK:  call void @llvm.dbg.value(metadata i32 %result.0, metadata !12, metadata !DIExpression()), !dbg !17
 
 ; ModuleID = 'pr38763.cpp'
 source_filename = "pr38763.cpp"
@@ -48,12 +48,12 @@ define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
 entry:
   %foo = alloca i32, align 4
   %foo.0..sroa_cast = bitcast i32* %foo to i8*
-  store volatile i32 4, i32* %foo, align 4
+  store volatile i32 4, i32* %foo, align 4, !tbaa !19
   %foo.0. = load volatile i32, i32* %foo, align 4
   %foo.0.4 = load volatile i32, i32* %foo, align 4
   call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !27
-  %cmp = icmp eq i32 %foo.0., 4, !dbg !28
-  br i1 %cmp, label %if.then, label %if.else, !dbg !30
+  %cmp = icmp eq i32 %foo.0., 4
+  br i1 %cmp, label %if.then, label %if.else
 
 if.then:                                          ; preds = %entry
   %add = add nsw i32 %foo.0.4, 2, !dbg !31
@@ -91,10 +91,12 @@ declare void @llvm.dbg.value(metadata, metadata, metadata) #2
 !10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
 !11 = !{!16}
 !16 = !DILocalVariable(name: "result", scope: !7, file: !1, line: 6, type: !10)
+!19 = !{!20, !20, i64 0}
+!20 = !{!"int", !21, i64 0}
+!21 = !{!"omnipotent char", !22, i64 0}
+!22 = !{!"Simple C++ TBAA"}
 !27 = !DILocation(line: 6, column: 7, scope: !7)
-!28 = !DILocation(line: 7, column: 12, scope: !29)
 !29 = distinct !DILexicalBlock(scope: !7, file: !1, line: 7, column: 7)
-!30 = !DILocation(line: 7, column: 7, scope: !7)
 !31 = !DILocation(line: 8, column: 20, scope: !32)
 !32 = distinct !DILexicalBlock(scope: !29, file: !1, line: 7, column: 18)
 !34 = !DILocation(line: 10, column: 20, scope: !35)