From: Stanislav Mekhanoshin <Stanislav.Mekhanoshin@amd.com>
Date: Sat, 11 Mar 2017 00:14:52 +0000 (+0000)
Subject: Fix subreg value numbers in handleMoveUp
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f99709a2dff295b1d82be44bc69f9ca0d14bdd76;p=llvm

Fix subreg value numbers in handleMoveUp

The problem can occur in presence of subregs. If we are swapping two
instructions defining different subregs of the same register we will
get a new liveout from a block. We need to preserve value number for
block's liveout for successor block's livein to match.

Differential Revision: https://reviews.llvm.org/D30558

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297534 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 2720609ab75..3f5b8e19d1f 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1232,10 +1232,12 @@ private:
           LiveRange::iterator NewIdxIn = NewIdxOut;
           assert(NewIdxIn == LR.find(NewIdx.getBaseIndex()));
           const SlotIndex SplitPos = NewIdxDef;
+          OldIdxVNI = OldIdxIn->valno;
 
           // Merge the OldIdxIn and OldIdxOut segments into OldIdxOut.
+          OldIdxOut->valno->def = OldIdxIn->start;
           *OldIdxOut = LiveRange::Segment(OldIdxIn->start, OldIdxOut->end,
-                                          OldIdxIn->valno);
+                                          OldIdxOut->valno);
           // OldIdxIn and OldIdxVNI are now undef and can be overridden.
           // We Slide [NewIdxIn, OldIdxIn) down one position.
           //    |- X0/NewIdxIn -| ... |- Xn-1 -||- Xn/OldIdxIn -||- OldIdxOut -|
diff --git a/unittests/MI/LiveIntervalTest.cpp b/unittests/MI/LiveIntervalTest.cpp
index 2fd2baecc79..026fb42d345 100644
--- a/unittests/MI/LiveIntervalTest.cpp
+++ b/unittests/MI/LiveIntervalTest.cpp
@@ -382,6 +382,24 @@ TEST(LiveIntervalTest, SubRegMoveDown) {
   });
 }
 
+TEST(LiveIntervalTest, SubRegMoveUp) {
+  // handleMoveUp had a bug not updating valno of segment incoming to bb.2
+  // after swapping subreg definitions.
+  liveIntervalTest(R"MIR(
+    successors: %bb.1, %bb.2
+    undef %0.sub0 = IMPLICIT_DEF
+    %0.sub1 = IMPLICIT_DEF
+    S_CBRANCH_VCCNZ %bb.2, implicit undef %vcc
+    S_BRANCH %bb.1
+  bb.1:
+    S_NOP 0, implicit %0.sub1
+  bb.2:
+    S_NOP 0, implicit %0.sub1
+)MIR", [](MachineFunction &MF, LiveIntervals &LIS) {
+    testHandleMove(MF, LIS, 1, 0);
+  });
+}
+
 int main(int argc, char **argv) {
   ::testing::InitGoogleTest(&argc, argv);
   initLLVM();