Simplify array bound checks and clarify comments. One element array can have same non-zero number as lower bound as well as upper bound.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129170 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 9 insertions, 11 deletions

diff --git a/docs/SourceLevelDebugging.html b/docs/SourceLevelDebugging.html
index 10c78f6..440f409 100644
--- a/docs/SourceLevelDebugging.html
+++ b/docs/SourceLevelDebugging.html
@@ -708,7 +708,8 @@ DW_TAG_inheritance      = 28
    <a href="#format_composite_type">composite type</a>.  The low value defines
    the lower bounds typically zero for C/C++.  The high value is the upper
    bounds.  Values are 64 bit.  High - low + 1 is the size of the array.  If low
-   > high the array will be unbounded.</p>
+   > high the array bounds are not included in generated debugging information.
+</p>
 
 </div>
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index b9bf37b..440099f 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1242,19 +1242,16 @@ void DwarfDebug::constructSubrangeDIE(DIE &Buffer, DISubrange SR, DIE *IndexTy){
   int64_t L = SR.getLo();
   int64_t H = SR.getHi();
 
-  // The L value defines the lower bounds typically zero for C/C++.  The H
-  // value is the upper bounds.  Values are 64 bit.  H - L + 1 is the size
-  // of the array. If L > H the array will be unbounded. If the L is 
-  // non zero and same is H then also the array will be unbounded. If L is
-  // zero and H is zero then the array has one element and in such case do
-  // not emit lower bound.
-
-  if (L > H || (L == H && L != 0)) {
-    // This is an unbounded subrange.
+  // The L value defines the lower bounds which is typically zero for C/C++. The
+  // H value is the upper bounds.  Values are 64 bit.  H - L + 1 is the size
+  // of the array. If L > H then do not emit DW_AT_lower_bound and 
+  // DW_AT_upper_bound attributes. If L is zero and H is also zero then the
+  // array has one element and in such case do not emit lower bound.
+
+  if (L > H) {
     Buffer.addChild(DW_Subrange);
     return;
   }
-
   if (L)
     addSInt(DW_Subrange, dwarf::DW_AT_lower_bound, 0, L);
   addSInt(DW_Subrange, dwarf::DW_AT_upper_bound, 0, H);