[llvm-branch-commits] [llvm-branch] r245457 - Merging r244448:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Wed Aug 19 11:43:16 2015
New Revision: 245457

URL: http://llvm.org/viewvc/llvm-project?rev=245457&view=rev
Log:
Merging r244448:
------------------------------------------------------------------------
r244448 | fcormack | 2015-08-10 07:48:47 -0700 (Mon, 10 Aug 2015) | 12 lines

Prevent the scalarizer from caching incorrect entries

The scalarizer can cache incorrect entries when walking up a chain of
insertelement instructions. This occurs when it encounters more than one
instruction that it is not actively searching for, as it unconditionally caches
every element it finds. The fix is to only cache the first element that it
isn't searching for so we don't overwrite correct entries.

Reviewers: hfinkel

Differential Revision: http://reviews.llvm.org/D11559

------------------------------------------------------------------------

Added:
    llvm/branches/release_37/test/Transforms/Scalarizer/cache-bug.ll
      - copied unchanged from r244448, llvm/trunk/test/Transforms/Scalarizer/cache-bug.ll
Modified:
    llvm/branches/release_37/   (props changed)
    llvm/branches/release_37/lib/Transforms/Scalar/Scalarizer.cpp

Propchange: llvm/branches/release_37/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Wed Aug 19 11:43:16 2015
@@ -1,3 +1,3 @@
 /llvm/branches/Apple/Pertwee:110850,110961
 /llvm/branches/type-system-rewrite:133420-134817
-/llvm/trunk:155241,242236,242239,242281,242288,242296,242331,242341,242410,242412,242433-242434,242442,242543,242673,242680,242706,242721-242722,242733-242735,242742,242869,242919,242993,243001,243057,243116,243263,243294,243361,243469,243485,243500,243519,243531,243589,243609,243636,243638-243640,243745,243891,243898,243927,243932,243934,243984,243986,243999,244058,244123,244232,244332,244418,244554,244644,244659,244676,244789,244889,245064,245105,245119,245256,245355
+/llvm/trunk:155241,242236,242239,242281,242288,242296,242331,242341,242410,242412,242433-242434,242442,242543,242673,242680,242706,242721-242722,242733-242735,242742,242869,242919,242993,243001,243057,243116,243263,243294,243361,243469,243485,243500,243519,243531,243589,243609,243636,243638-243640,243745,243891,243898,243927,243932,243934,243984,243986,243999,244058,244123,244232,244332,244418,244448,244554,244644,244659,244676,244789,244889,245064,245105,245119,245256,245355

Modified: llvm/branches/release_37/lib/Transforms/Scalar/Scalarizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_37/lib/Transforms/Scalar/Scalarizer.cpp?rev=245457&r1=245456&r2=245457&view=diff
==============================================================================
--- llvm/branches/release_37/lib/Transforms/Scalar/Scalarizer.cpp (original)
+++ llvm/branches/release_37/lib/Transforms/Scalar/Scalarizer.cpp Wed Aug 19 11:43:16 2015
@@ -227,10 +227,16 @@ Value *Scatterer::operator[](unsigned I)
       if (!Idx)
         break;
       unsigned J = Idx->getZExtValue();
-      CV[J] = Insert->getOperand(1);
       V = Insert->getOperand(0);
-      if (I == J)
+      if (I == J) {
+        CV[J] = Insert->getOperand(1);
         return CV[J];
+      } else if (!CV[J]) {
+        // Only cache the first entry we find for each index we're not actively
+        // searching for. This prevents us from going too far up the chain and
+        // caching incorrect entries.
+        CV[J] = Insert->getOperand(1);
+      }
     }
     CV[I] = Builder.CreateExtractElement(V, Builder.getInt32(I),
                                          V->getName() + ".i" + Twine(I));