Cherry-pick r293372.

lib/Transforms/Utils/SimplifyCFG.cpp

@@ -1280,7 +1280,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
     if (!isa<CallInst>(I1))
       I1->setDebugLoc(
           DILocation::getMergedLocation(I1->getDebugLoc(), I2->getDebugLoc()));
- 
+
     I2->eraseFromParent();
     Changed = true;
 
@@ -1546,7 +1546,7 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
         }))
       return false;
   }
-  
+
   // We don't need to do any more checking here; canSinkLastInstruction should
   // have done it all for us.
   SmallVector<Value*, 4> NewOperands;
@@ -1653,7 +1653,7 @@ namespace {
     bool isValid() const {
       return !Fail;
     }
-    
+
     void operator -- () {
       if (Fail)
         return;
@@ -1737,7 +1737,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
   }
   if (UnconditionalPreds.size() < 2)
     return false;
-  
+
   bool Changed = false;
   // We take a two-step approach to tail sinking. First we scan from the end of
   // each block upwards in lockstep. If the n'th instruction from the end of each
@@ -1767,7 +1767,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
     unsigned NumPHIInsts = NumPHIdValues / UnconditionalPreds.size();
     if ((NumPHIdValues % UnconditionalPreds.size()) != 0)
         NumPHIInsts++;
-    
+
     return NumPHIInsts <= 1;
   };
 
@@ -1790,7 +1790,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
     }
     if (!Profitable)
       return false;
-    
+
     DEBUG(dbgs() << "SINK: Splitting edge\n");
     // We have a conditional edge and we're going to sink some instructions.
     // Insert a new block postdominating all blocks we're going to sink from.
@@ -1800,7 +1800,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
       return false;
     Changed = true;
   }
-  
+
   // Now that we've analyzed all potential sinking candidates, perform the
   // actual sink. We iteratively sink the last non-terminator of the source
   // blocks into their common successor unless doing so would require too
@@ -1826,7 +1826,7 @@ static bool SinkThenElseCodeToEnd(BranchInst *BI1) {
       DEBUG(dbgs() << "SINK: stopping here, too many PHIs would be created!\n");
       break;
     }
-    
+
     if (!sinkLastInstruction(UnconditionalPreds))
       return Changed;
     NumSinkCommons++;
@@ -2078,6 +2078,9 @@ static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
     Value *S = Builder.CreateSelect(
         BrCond, TrueV, FalseV, TrueV->getName() + "." + FalseV->getName(), BI);
     SpeculatedStore->setOperand(0, S);
+    SpeculatedStore->setDebugLoc(
+        DILocation::getMergedLocation(
+          BI->getDebugLoc(), SpeculatedStore->getDebugLoc()));
   }
 
   // Metadata can be dependent on the condition we are hoisting above.

test/Transforms/SimplifyCFG/remove-debug-2.ll

@@ -0,0 +1,68 @@
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
+
+; Check if the debug info for hoisted store for "ret = 0" is removed
+;
+; int foo(int x) {
+;   int ret = 1;
+;   if (x)
+;     ret = 0;
+;   return ret;
+; }
+;
+; CHECK: store i32 1,{{.+}}!dbg ![[DLOC1:[0-9]+]]
+; CHECK: icmp ne {{.+}}!dbg ![[DLOC2:[0-9]+]]
+; CHECK: [[VREG:%[^ ]+]] = select
+; CHECK: store i32 [[VREG]]
+; CHECK-NOT: !dbg
+; CHECK-SAME: {{$}}
+; CHECK: ret {{.+}}!dbg ![[DLOC3:[0-9]+]]
+; CHECK: ![[DLOC1]] = !DILocation(line: 2
+; CHECK: ![[DLOC2]] = !DILocation(line: 3
+; CHECK: ![[DLOC3]] = !DILocation(line: 5
+
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: noinline nounwind uwtable
+define i32 @foo(i32) !dbg !6 {
+  %2 = alloca i32, align 4
+  %3 = alloca i32, align 4
+  store i32 %0, i32* %2, align 4
+  store i32 1, i32* %3, align 4, !dbg !14
+  %4 = load i32, i32* %2, align 4, !dbg !15
+  %5 = icmp ne i32 %4, 0, !dbg !15
+  br i1 %5, label %6, label %7, !dbg !17
+
+; <label>:6:                                      ; preds = %1
+  store i32 0, i32* %3, align 4, !dbg !18
+  br label %7, !dbg !19
+
+; <label>:7:                                      ; preds = %6, %1
+  %8 = load i32, i32* %3, align 4, !dbg !20
+  ret i32 %8, !dbg !21
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
+!1 = !DIFile(filename: "foo.c", directory: "b/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !9}
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DILocalVariable(name: "x", arg: 1, scope: !6, file: !1, line: 1, type: !9)
+!11 = !DIExpression()
+!12 = !DILocation(line: 1, column: 13, scope: !6)
+!13 = !DILocalVariable(name: "ret", scope: !6, file: !1, line: 2, type: !9)
+!14 = !DILocation(line: 2, column: 7, scope: !6)
+!15 = !DILocation(line: 3, column: 7, scope: !16)
+!16 = distinct !DILexicalBlock(scope: !6, file: !1, line: 3, column: 7)
+!17 = !DILocation(line: 3, column: 7, scope: !6)
+!18 = !DILocation(line: 4, column: 9, scope: !16)
+!19 = !DILocation(line: 4, column: 5, scope: !16)
+!20 = !DILocation(line: 5, column: 10, scope: !6)
+!21 = !DILocation(line: 5, column: 3, scope: !6)