Fix a crash when building 177.mesa for armv6.

When splitting a live range immediately before an LDR_POST instruction
that redefines the address register, make sure to use the correct value
number in leaveIntvBefore.

We need the value number entering the instruction.

<rdar://problem/9793765>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135413 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 33 insertions, 1 deletions

diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 761cab7ce8..5ba6faca16 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -730,7 +730,7 @@ SlotIndex SplitEditor::leaveIntvBefore(SlotIndex Idx) {
   DEBUG(dbgs() << "    leaveIntvBefore " << Idx);
 
   // The interval must be live into the instruction at Idx.
-  Idx = Idx.getBoundaryIndex();
+  Idx = Idx.getBaseIndex();
   VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
   if (!ParentVNI) {
     DEBUG(dbgs() << ": not live\n");
diff --git a/test/CodeGen/ARM/crash-greedy-v6.ll b/test/CodeGen/ARM/crash-greedy-v6.ll
new file mode 100644
index 0000000000..fd42254767
--- /dev/null
+++ b/test/CodeGen/ARM/crash-greedy-v6.ll
@@ -0,0 +1,32 @@
+; RUN: llc -disable-fp-elim -relocation-model=pic < %s
+target triple = "armv6-apple-ios"
+
+; Reduced from 177.mesa. This test causes a live range split before an LDR_POST instruction.
+; That requires leaveIntvBefore to be very accurate about the redefined value number.
+define internal void @sample_nearest_3d(i8* nocapture %tObj, i32 %n, float* nocapture %s, float* nocapture %t, float* nocapture %u, float* nocapture %lambda, i8* nocapture %red, i8* nocapture %green, i8* nocapture %blue, i8* nocapture %alpha) nounwind ssp {
+entry:
+  br i1 undef, label %for.end, label %for.body.lr.ph
+
+for.body.lr.ph:                                   ; preds = %entry
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %for.body.lr.ph
+  %i.031 = phi i32 [ 0, %for.body.lr.ph ], [ %0, %for.body ]
+  %arrayidx11 = getelementptr float* %t, i32 %i.031
+  %arrayidx15 = getelementptr float* %u, i32 %i.031
+  %arrayidx19 = getelementptr i8* %red, i32 %i.031
+  %arrayidx22 = getelementptr i8* %green, i32 %i.031
+  %arrayidx25 = getelementptr i8* %blue, i32 %i.031
+  %arrayidx28 = getelementptr i8* %alpha, i32 %i.031
+  %tmp12 = load float* %arrayidx11, align 4
+  tail call fastcc void @sample_3d_nearest(i8* %tObj, i8* undef, float undef, float %tmp12, float undef, i8* %arrayidx19, i8* %arrayidx22, i8* %arrayidx25, i8* %arrayidx28)
+  %0 = add i32 %i.031, 1
+  %exitcond = icmp eq i32 %0, %n
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body, %entry
+  ret void
+}
+
+declare fastcc void @sample_3d_nearest(i8* nocapture, i8* nocapture, float, float, float, i8* nocapture, i8* nocapture, i8* nocapture, i8* nocapture) nounwind ssp
+