[llvm-branch-commits] [llvm-branch] r260121 - Merging r259696:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Mon Feb  8 12:31:49 2016
New Revision: 260121

URL: http://llvm.org/viewvc/llvm-project?rev=260121&view=rev
Log:
Merging r259696:
------------------------------------------------------------------------
r259696 | kfischer | 2016-02-03 13:13:33 -0800 (Wed, 03 Feb 2016) | 12 lines

[DWARFDebug] Fix another case of overlapping ranges

Summary:
In r257979, I added code to ensure that we wouldn't merge DebugLocEntries if
the pieces they describe overlap. Unfortunately, I failed to cover the case,
where there may have multiple active Expressions in the entry, in which case we
need to make sure that no two values overlap before we can perform the merge.

This fixed PR26148.

Reviewers: aprantl
Differential Revision: http://reviews.llvm.org/D16742
------------------------------------------------------------------------

Added:
    llvm/branches/release_38/test/DebugInfo/X86/PR26148.ll
      - copied unchanged from r259696, llvm/trunk/test/DebugInfo/X86/PR26148.ll
Modified:
    llvm/branches/release_38/   (props changed)
    llvm/branches/release_38/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

Propchange: llvm/branches/release_38/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Mon Feb  8 12:31:49 2016
@@ -1,3 +1,3 @@
 /llvm/branches/Apple/Pertwee:110850,110961
 /llvm/branches/type-system-rewrite:133420-134817
-/llvm/trunk:155241,257645,257648,257730,257775,257791,257875,257886,257902,257905,257925,257929-257930,257940,257942,257977,257979,257997,258168,258184,258207,258221,258273,258325,258406,258416,258428,258436,258471,258690,258729,258891,258971,259177-259178,259228,259236,259342,259346,259375,259381,259645,259649,259695,259740,259798,259835,259840,259886,259888
+/llvm/trunk:155241,257645,257648,257730,257775,257791,257875,257886,257902,257905,257925,257929-257930,257940,257942,257977,257979,257997,258168,258184,258207,258221,258273,258325,258406,258416,258428,258436,258471,258690,258729,258891,258971,259177-259178,259228,259236,259342,259346,259375,259381,259645,259649,259695-259696,259740,259798,259835,259840,259886,259888

Modified: llvm/branches/release_38/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_38/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=260121&r1=260120&r2=260121&view=diff
==============================================================================
--- llvm/branches/release_38/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
+++ llvm/branches/release_38/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Mon Feb  8 12:31:49 2016
@@ -793,16 +793,27 @@ static DebugLocEntry::Value getDebugLocV
   llvm_unreachable("Unexpected 4-operand DBG_VALUE instruction!");
 }
 
-/// Determine whether two variable pieces overlap.
-static bool piecesOverlap(const DIExpression *P1, const DIExpression *P2) {
-  if (!P1->isBitPiece() || !P2->isBitPiece())
-    return true;
+// Determine the relative position of the pieces described by P1 and P2.
+// Returns  -1 if P1 is entirely before P2, 0 if P1 and P2 overlap,
+// 1 if P1 is entirely after P2.
+static int pieceCmp(const DIExpression *P1, const DIExpression *P2) {
   unsigned l1 = P1->getBitPieceOffset();
   unsigned l2 = P2->getBitPieceOffset();
   unsigned r1 = l1 + P1->getBitPieceSize();
   unsigned r2 = l2 + P2->getBitPieceSize();
-  // True where [l1,r1[ and [r1,r2[ overlap.
-  return (l1 < r2) && (l2 < r1);
+  if (r1 <= l2)
+    return -1;
+  else if (r2 <= l1)
+    return 1;
+  else
+    return 0;
+}
+
+/// Determine whether two variable pieces overlap.
+static bool piecesOverlap(const DIExpression *P1, const DIExpression *P2) {
+  if (!P1->isBitPiece() || !P2->isBitPiece())
+    return true;
+  return pieceCmp(P1, P2) == 0;
 }
 
 /// \brief If this and Next are describing different pieces of the same
@@ -811,14 +822,32 @@ static bool piecesOverlap(const DIExpres
 /// Return true if the merge was successful.
 bool DebugLocEntry::MergeValues(const DebugLocEntry &Next) {
   if (Begin == Next.Begin) {
-    auto *Expr = cast_or_null<DIExpression>(Values[0].Expression);
-    auto *NextExpr = cast_or_null<DIExpression>(Next.Values[0].Expression);
-    if (Expr->isBitPiece() && NextExpr->isBitPiece() &&
-        !piecesOverlap(Expr, NextExpr)) {
-      addValues(Next.Values);
-      End = Next.End;
-      return true;
+    auto *FirstExpr = cast<DIExpression>(Values[0].Expression);
+    auto *FirstNextExpr = cast<DIExpression>(Next.Values[0].Expression);
+    if (!FirstExpr->isBitPiece() || !FirstNextExpr->isBitPiece())
+      return false;
+
+    // We can only merge entries if none of the pieces overlap any others.
+    // In doing so, we can take advantage of the fact that both lists are
+    // sorted.
+    for (unsigned i = 0, j = 0; i < Values.size(); ++i) {
+      for (; j < Next.Values.size(); ++j) {
+        int res = pieceCmp(cast<DIExpression>(Values[i].Expression),
+                           cast<DIExpression>(Next.Values[j].Expression));
+        if (res == 0) // The two expressions overlap, we can't merge.
+          return false;
+        // Values[i] is entirely before Next.Values[j],
+        // so go back to the next entry of Values.
+        else if (res == -1)
+          break;
+        // Next.Values[j] is entirely before Values[i], so go on to the
+        // next entry of Next.Values.
+      }
     }
+
+    addValues(Next.Values);
+    End = Next.End;
+    return true;
   }
   return false;
 }