[llvm-branch-commits] [llvm-branch] r370182 - Merging r369886:

[Hans Wennborg via llvm-branch-commits]

Author: hans
Date: Wed Aug 28 02:55:07 2019
New Revision: 370182

URL: http://llvm.org/viewvc/llvm-project?rev=370182&view=rev
Log:
Merging r369886:
------------------------------------------------------------------------
r369886 | bjope | 2019-08-26 11:29:53 +0200 (Mon, 26 Aug 2019) | 23 lines

[LoopUnroll] Handle certain PHIs in full unrolling properly

Summary:
When reconstructing the CFG of the loop after unrolling,
LoopUnroll could in some cases remove the phi operands of
loop-carried values instead of preserving them, resulting
in undef phi values after loop unrolling.

When doing this reconstruction, avoid removing incoming
phi values for phis in the successor blocks if the successor
is the block we are jumping to anyway.

Patch-by: ebevhan

Reviewers: fhahn, efriedma

Reviewed By: fhahn

Subscribers: bjope, lebedev.ri, zzheng, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66334
------------------------------------------------------------------------

Added:
    llvm/branches/release_90/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
      - copied unchanged from r369886, llvm/trunk/test/Transforms/LoopUnroll/unroll-header-exiting-with-phis.ll
Modified:
    llvm/branches/release_90/   (props changed)
    llvm/branches/release_90/lib/Transforms/Utils/LoopUnroll.cpp

Propchange: llvm/branches/release_90/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Wed Aug 28 02:55:07 2019
@@ -1,3 +1,3 @@
 /llvm/branches/Apple/Pertwee:110850,110961
 /llvm/branches/type-system-rewrite:133420-134817
-/llvm/trunk:155241,366431,366447,366481,366487,366527,366570,366660,366868,366925,367019,367030,367062,367084,367124,367215,367292,367304,367306,367314,367340-367341,367394,367396,367398,367403,367412,367417,367429,367580,367662,367750,367753,367846-367847,367898,367941,368004,368230,368300,368315,368324,368477-368478,368517-368519,368554,368572,368873,369011,369026,369084,369095,369097,369168,369199,369426,369443,370036,370176
+/llvm/trunk:155241,366431,366447,366481,366487,366527,366570,366660,366868,366925,367019,367030,367062,367084,367124,367215,367292,367304,367306,367314,367340-367341,367394,367396,367398,367403,367412,367417,367429,367580,367662,367750,367753,367846-367847,367898,367941,368004,368230,368300,368315,368324,368477-368478,368517-368519,368554,368572,368873,369011,369026,369084,369095,369097,369168,369199,369426,369443,369886,370036,370176

Modified: llvm/branches/release_90/lib/Transforms/Utils/LoopUnroll.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_90/lib/Transforms/Utils/LoopUnroll.cpp?rev=370182&r1=370181&r2=370182&view=diff
==============================================================================
--- llvm/branches/release_90/lib/Transforms/Utils/LoopUnroll.cpp (original)
+++ llvm/branches/release_90/lib/Transforms/Utils/LoopUnroll.cpp Wed Aug 28 02:55:07 2019
@@ -711,7 +711,7 @@ LoopUnrollResult llvm::UnrollLoop(Loop *
 
   auto setDest = [LoopExit, ContinueOnTrue](BasicBlock *Src, BasicBlock *Dest,
                                             ArrayRef<BasicBlock *> NextBlocks,
-                                            BasicBlock *CurrentHeader,
+                                            BasicBlock *BlockInLoop,
                                             bool NeedConditional) {
     auto *Term = cast<BranchInst>(Src->getTerminator());
     if (NeedConditional) {
@@ -723,7 +723,9 @@ LoopUnrollResult llvm::UnrollLoop(Loop *
       if (Dest != LoopExit) {
         BasicBlock *BB = Src;
         for (BasicBlock *Succ : successors(BB)) {
-          if (Succ == CurrentHeader)
+          // Preserve the incoming value from BB if we are jumping to the block
+          // in the current loop.
+          if (Succ == BlockInLoop)
             continue;
           for (PHINode &Phi : Succ->phis())
             Phi.removeIncomingValue(BB, false);
@@ -794,7 +796,7 @@ LoopUnrollResult llvm::UnrollLoop(Loop *
         // unconditional branch for some iterations.
         NeedConditional = false;
 
-      setDest(Headers[i], Dest, Headers, Headers[i], NeedConditional);
+      setDest(Headers[i], Dest, Headers, HeaderSucc[i], NeedConditional);
     }
 
     // Set up latches to branch to the new header in the unrolled iterations or