Don't add a fragment expression when GlobalSRA splits up a single-member struct

Fixes PR34390.

https://bugs.llvm.org/show_bug.cgi?id=34390

llvm-svn: 312196

2 files changed, 65 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 68d745f7ed3..ee8fdaebbda 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -420,15 +420,17 @@ static bool GlobalUsersSafeToSRA(GlobalValue *GV) {
 /// Copy over the debug info for a variable to its SRA replacements.
 static void transferSRADebugInfo(GlobalVariable *GV, GlobalVariable *NGV,
                                  uint64_t FragmentOffsetInBits,
-                                 uint64_t FragmentSizeInBits) {
+                                 uint64_t FragmentSizeInBits,
+                                 unsigned NumElements) {
   SmallVector<DIGlobalVariableExpression *, 1> GVs;
   GV->getDebugInfo(GVs);
   for (auto *GVE : GVs) {
     DIVariable *Var = GVE->getVariable();
     DIExpression *Expr = GVE->getExpression();
-    auto *NExpr = DIExpression::createFragmentExpression(
-        Expr, FragmentOffsetInBits, FragmentSizeInBits);
-    auto *NGVE = DIGlobalVariableExpression::get(GVE->getContext(), Var, NExpr);
+    if (NumElements > 1)
+      Expr = DIExpression::createFragmentExpression(Expr, FragmentOffsetInBits,
+                                                    FragmentSizeInBits);
+    auto *NGVE = DIGlobalVariableExpression::get(GVE->getContext(), Var, Expr);
     NGV->addDebugInfo(NGVE);
   }
 }
@@ -458,9 +460,10 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
 
   if (StructType *STy = dyn_cast<StructType>(Ty)) {
     uint64_t FragmentOffset = 0;
-    NewGlobals.reserve(STy->getNumElements());
+    unsigned NumElements = STy->getNumElements();
+    NewGlobals.reserve(NumElements);
     const StructLayout &Layout = *DL.getStructLayout(STy);
-    for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
+    for (unsigned i = 0, e = NumElements; i != e; ++i) {
       Constant *In = Init->getAggregateElement(i);
       assert(In && "Couldn't get element of initializer?");
       GlobalVariable *NGV = new GlobalVariable(STy->getElementType(i), false,
@@ -484,7 +487,7 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
       // Copy over the debug info for the variable.
       FragmentOffset = alignTo(FragmentOffset, NewAlign);
       uint64_t Size = DL.getTypeSizeInBits(NGV->getValueType());
-      transferSRADebugInfo(GV, NGV, FragmentOffset, Size);
+      transferSRADebugInfo(GV, NGV, FragmentOffset, Size, NumElements);
       FragmentOffset += Size;
     }
   } else if (SequentialType *STy = dyn_cast<SequentialType>(Ty)) {
@@ -516,8 +519,8 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
       unsigned NewAlign = (unsigned)MinAlign(StartAlignment, EltSize*i);
       if (NewAlign > EltAlign)
         NGV->setAlignment(NewAlign);
-
-      transferSRADebugInfo(GV, NGV, FragmentSizeInBits * i, FragmentSizeInBits);
+      transferSRADebugInfo(GV, NGV, FragmentSizeInBits * i, FragmentSizeInBits,
+                           NumElements);
     }
   }
 
diff --git a/llvm/test/DebugInfo/Generic/global-sra-single-member.ll b/llvm/test/DebugInfo/Generic/global-sra-single-member.ll
new file mode 100644
index 00000000000..1e3fef3a5d9
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/global-sra-single-member.ll
@@ -0,0 +1,53 @@
+; RUN: opt -S -globalopt < %s | FileCheck %s
+; struct {
+;   int f0;
+; } static a;
+; int main() {
+;   a.f0++;
+;   return 0;
+; }
+
+source_filename = "pr34390.c"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.12.0"
+
+%struct.anon = type { i32 }
+
+; CHECK: @a.0 = internal unnamed_addr global i32 0, align 4, !dbg ![[GVE:.*]]
+@a = internal global %struct.anon zeroinitializer, align 4, !dbg !0
+
+define i32 @main() #0 !dbg !15 {
+entry:
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  %0 = load i32, i32* getelementptr inbounds (%struct.anon, %struct.anon* @a, i32 0, i32 0), align 4, !dbg !18
+  %inc = add nsw i32 %0, 1, !dbg !18
+  store i32 %inc, i32* getelementptr inbounds (%struct.anon, %struct.anon* @a, i32 0, i32 0), align 4, !dbg !18
+  ret i32 0, !dbg !19
+}
+
+attributes #0 = { noinline nounwind optnone ssp uwtable }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!10, !11, !12, !13}
+
+; CHECK: ![[GVE]] = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 3, type: !6, isLocal: true, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 6.0.0 (trunk 312175) (llvm/trunk 312146)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
+!3 = !DIFile(filename: "test.c", directory: "/")
+!4 = !{}
+!5 = !{!0}
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !3, line: 1, size: 32, elements: !7)
+!7 = !{!8}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "f0", scope: !6, file: !3, line: 2, baseType: !9, size: 32)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{i32 2, !"Dwarf Version", i32 4}
+!11 = !{i32 2, !"Debug Info Version", i32 3}
+!12 = !{i32 1, !"wchar_size", i32 4}
+!13 = !{i32 7, !"PIC Level", i32 2}
+!15 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 4, type: !16, isLocal: false, isDefinition: true, scopeLine: 4, isOptimized: false, unit: !2, variables: !4)
+!16 = !DISubroutineType(types: !17)
+!17 = !{!9}
+!18 = !DILocation(line: 5, column: 7, scope: !15)
+!19 = !DILocation(line: 6, column: 3, scope: !15)