6 files changed, 156 insertions, 2 deletions
diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
index 2592d43819d..6650afcca7f 100644
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -93,6 +93,10 @@ namespace llvm {
       return cast<MetadataAsValue>(getArgOperand(2))->getMetadata();
     }
 
+    /// Get the size (in bits) of the variable, or fragment of the variable that
+    /// is described.
+    Optional<uint64_t> getFragmentSizeInBits() const;
+
     /// \name Casting methods
     /// @{
     static bool classof(const IntrinsicInst *I) {
diff --git a/llvm/lib/IR/IntrinsicInst.cpp b/llvm/lib/IR/IntrinsicInst.cpp
index 67bd5b69bb0..9ffcae1f8f8 100644
--- a/llvm/lib/IR/IntrinsicInst.cpp
+++ b/llvm/lib/IR/IntrinsicInst.cpp
@@ -24,6 +24,7 @@
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
@@ -48,6 +49,12 @@ Value *DbgInfoIntrinsic::getVariableLocation(bool AllowNullOp) const {
   return nullptr;
 }
 
+Optional<uint64_t> DbgInfoIntrinsic::getFragmentSizeInBits() const {
+  if (auto Fragment = getExpression()->getFragmentInfo())
+    return Fragment->SizeInBits;
+  return getVariable()->getSizeInBits();
+}
+
 int llvm::Intrinsic::lookupLLVMIntrinsicByName(ArrayRef<const char *> NameTable,
                                                StringRef Name) {
   assert(Name.startswith("llvm."));
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 406b52607f0..3d976005cba 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1228,6 +1228,23 @@ static bool PhiHasDebugValue(DILocalVariable *DIVar,
   return false;
 }
 
+/// Check if the alloc size of \p ValTy is large enough to cover the variable
+/// (or fragment of the variable) described by \p DII.
+///
+/// This is primarily intended as a helper for the different
+/// ConvertDebugDeclareToDebugValue functions. The dbg.declare/dbg.addr that is
+/// converted describes an alloca'd variable, so we need to use the
+/// alloc size of the value when doing the comparison. E.g. an i1 value will be
+/// identified as covering an n-bit fragment, if the store size of i1 is at
+/// least n bits.
+static bool valueCoversEntireFragment(Type *ValTy, DbgInfoIntrinsic *DII) {
+  const DataLayout &DL = DII->getModule()->getDataLayout();
+  uint64_t ValueSize = DL.getTypeAllocSizeInBits(ValTy);
+  if (auto FragmentSize = DII->getFragmentSizeInBits())
+    return ValueSize >= *FragmentSize;
+  return false;
+}
+
 /// Inserts a llvm.dbg.value intrinsic before a store to an alloca'd value
 /// that has an associated llvm.dbg.declare or llvm.dbg.addr intrinsic.
 void llvm::ConvertDebugDeclareToDebugValue(DbgInfoIntrinsic *DII,
@@ -1238,6 +1255,21 @@ void llvm::ConvertDebugDeclareToDebugValue(DbgInfoIntrinsic *DII,
   auto *DIExpr = DII->getExpression();
   Value *DV = SI->getOperand(0);
 
+  if (!valueCoversEntireFragment(SI->getValueOperand()->getType(), DII)) {
+    // FIXME: If storing to a part of the variable described by the dbg.declare,
+    // then we want to insert a dbg.value for the corresponding fragment.
+    LLVM_DEBUG(dbgs() << "Failed to convert dbg.declare to dbg.value: "
+                      << *DII << '\n');
+    // For now, when there is a store to parts of the variable (but we do not
+    // know which part) we insert an dbg.value instrinsic to indicate that we
+    // know nothing about the variable's content.
+    DV = UndefValue::get(DV->getType());
+    if (!LdStHasDebugValue(DIVar, DIExpr, SI))
+      Builder.insertDbgValueIntrinsic(DV, DIVar, DIExpr, DII->getDebugLoc(),
+                                      SI);
+    return;
+  }
+
   // If an argument is zero extended then use argument directly. The ZExt
   // may be zapped by an optimization pass in future.
   Argument *ExtendedArg = nullptr;
@@ -1281,6 +1313,9 @@ void llvm::ConvertDebugDeclareToDebugValue(DbgInfoIntrinsic *DII,
   if (LdStHasDebugValue(DIVar, DIExpr, LI))
     return;
 
+  assert(valueCoversEntireFragment(LI->getType(), DII) &&
+         "Load is not loading the full variable fragment.");
+
   // We are now tracking the loaded value instead of the address. In the
   // future if multi-location support is added to the IR, it might be
   // preferable to keep tracking both the loaded value and the original
@@ -1301,6 +1336,9 @@ void llvm::ConvertDebugDeclareToDebugValue(DbgInfoIntrinsic *DII,
   if (PhiHasDebugValue(DIVar, DIExpr, APN))
     return;
 
+  assert(valueCoversEntireFragment(APN->getType(), DII) &&
+         "PHI node is not describing the full variable.");
+
   BasicBlock *BB = APN->getParent();
   auto InsertionPt = BB->getFirstInsertionPt();
 
diff --git a/llvm/test/DebugInfo/X86/mem2reg_fp80.ll b/llvm/test/DebugInfo/X86/mem2reg_fp80.ll
new file mode 100644
index 00000000000..fa79c61b30e
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/mem2reg_fp80.ll
@@ -0,0 +1,57 @@
+; RUN: opt < %s -mem2reg -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local x86_fp80 @powixf2() !dbg !1 {
+entry:
+  %r = alloca x86_fp80, align 16
+  call void @llvm.dbg.declare(metadata x86_fp80* %r, metadata !14, metadata !DIExpression()), !dbg !15
+  br i1 undef, label %if.then, label %if.end, !dbg !16
+
+if.then:                                          ; preds = %entry
+; CHECK-label: if.then:
+; CHECK: %mul = fmul x86_fp80
+; CHECK: call void @llvm.dbg.value(metadata x86_fp80 %mul, metadata {{.*}}, metadata !DIExpression())
+  %mul = fmul x86_fp80 undef, undef, !dbg !18
+  store x86_fp80 %mul, x86_fp80* %r, align 16, !dbg !18
+  br label %if.end, !dbg !20
+
+if.end:                                           ; preds = %if.then, %entry
+; CHECK-label: if.end:
+; CHECK: %r.0 = phi x86_fp80
+; CHECK: call void @llvm.dbg.value(metadata x86_fp80 %r.0, metadata {{.*}}, metadata !DIExpression())
+  %out = load x86_fp80, x86_fp80* %r, align 16, !dbg !21
+  ret x86_fp80 %out, !dbg !22
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
+
+attributes #0 = { nounwind readnone speculatable }
+
+!llvm.dbg.cu = !{}
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+!1 = distinct !DISubprogram(name: "__powixf2", scope: !2, file: !2, line: 22, type: !3, isLocal: false, isDefinition: true, scopeLine: 23, flags: DIFlagPrototyped, isOptimized: true, unit: !11, retainedNodes: !13)
+!2 = !DIFile(filename: "powixf2.c", directory: "")
+!3 = !DISubroutineType(types: !4)
+!4 = !{!5, !5, !6}
+!5 = !DIBasicType(name: "long double", size: 128, encoding: DW_ATE_float)
+!6 = !DIDerivedType(tag: DW_TAG_typedef, name: "si_int", file: !7, line: 28, baseType: !8)
+!7 = !DIFile(filename: "int_types.h", directory: "")
+!8 = !DIDerivedType(tag: DW_TAG_typedef, name: "int32_t", file: !9, line: 39, baseType: !10)
+!9 = !DIFile(filename: "/usr/include/stdint.h", directory: "")
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, producer: "clang version 7.0.0 () ()", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !12)
+!12 = !{}
+!13 = !{!14}
+!14 = !DILocalVariable(name: "r", scope: !1, file: !2, line: 25, type: !5)
+!15 = !DILocation(line: 25, column: 17, scope: !1)
+!16 = !DILocation(line: 28, column: 13, scope: !17)
+!17 = distinct !DILexicalBlock(scope: !1, file: !2, line: 27, column: 5)
+!18 = !DILocation(line: 29, column: 15, scope: !19)
+!19 = distinct !DILexicalBlock(scope: !17, file: !2, line: 28, column: 13)
+!20 = !DILocation(line: 29, column: 13, scope: !19)
+!21 = !DILocation(line: 35, column: 22, scope: !1)
+!22 = !DILocation(line: 35, column: 5, scope: !1)
diff --git a/llvm/test/Transforms/InstCombine/debuginfo.ll b/llvm/test/Transforms/InstCombine/debuginfo.ll
index 4340c254165..05466590a01 100644
--- a/llvm/test/Transforms/InstCombine/debuginfo.ll
+++ b/llvm/test/Transforms/InstCombine/debuginfo.ll
@@ -71,9 +71,11 @@ entry:
 ; NOLOWER-NOT: alloca
 ; NOLOWER-NOT: store
 ; NOLOWER-NOT: call void @llvm.dbg.declare
-; NOLOWER: call void @llvm.dbg.value(metadata i64 %o.coerce0, {{.*}})
+; Here we want to find:  call void @llvm.dbg.value(metadata i64 %o.coerce0, metadata [[VARIABLE_O]], metadata !DIExpression(DW_OP_LLVM_fragment, 0, 64))
+; NOLOWER: call void @llvm.dbg.value(metadata i64 undef, {{.*}})
 ; NOLOWER-NOT: store
-; NOLOWER: call void @llvm.dbg.value(metadata i64 %o.coerce1, {{.*}})
+; Here we want to find:  call void @llvm.dbg.value(metadata i64 %o.coerce1, metadata [[VARIABLE_O]], metadata !DIExpression(DW_OP_LLVM_fragment, 64, 64))
+; NOLOWER: call void @llvm.dbg.value(metadata i64 undef, {{.*}})
 ; NOLOWER-NOT: store
 ; NOLOWER: call void @tworegs_callee(i64 %o.coerce0, i64 %o.coerce1)
 
diff --git a/llvm/test/Transforms/Mem2Reg/debug-alloca-phi-2.ll b/llvm/test/Transforms/Mem2Reg/debug-alloca-phi-2.ll
new file mode 100644
index 00000000000..82144cb228e
--- /dev/null
+++ b/llvm/test/Transforms/Mem2Reg/debug-alloca-phi-2.ll
@@ -0,0 +1,46 @@
+; RUN: opt < %s -mem2reg -S | FileCheck %s
+source_filename = "bugpoint-output.bc"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.12.0"
+
+define void @scan() #0 !dbg !12 {
+entry:
+  %entry1 = alloca i1, align 8
+  call void @llvm.dbg.declare(metadata i1* %entry1, metadata !18, metadata !19), !dbg !20
+  store i1 0, i1* %entry1, align 8, !dbg !20
+  br label %for.cond, !dbg !20
+
+for.cond:
+; CHECK: %[[PHI:.*]] = phi i1 [ false, %entry ], [ %0, %for.cond ]
+  %entryN = load i1, i1* %entry1, align 8, !dbg !20
+; CHECK: call void @llvm.dbg.value(metadata i1 %[[PHI]],
+; CHECK-SAME:                      metadata !DIExpression())
+  %0 = add i1 %entryN, 1
+; CHECK: %0 = add i1 %[[PHI]], true
+; CHECK: call void @llvm.dbg.value(metadata i1 %0,
+; CHECK-SAME:                      metadata !DIExpression())
+  store i1 %0, i1* %entry1, align 8, !dbg !20
+  br label %for.cond, !dbg !20
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { nounwind ssp uwtable }
+attributes #1 = { nounwind readnone }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!10, !11}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "adrian", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug)
+!1 = !DIFile(filename: "<stdin>", directory: "/")
+!2 = !{}
+!4 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{i32 1, !"PIC Level", i32 2}
+!12 = distinct !DISubprogram(name: "scan", scope: !1, file: !1, line: 4, type: !13, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !15)
+!13 = !DISubroutineType(types: !14)
+!14 = !{null, !4, !4}
+!15 = !{!18}
+!18 = !DILocalVariable(name: "entry", scope: !12, file: !1, line: 6, type: !4)
+!19 = !DIExpression()
+!20 = !DILocation(line: 6, scope: !12)