Do not try to optimize a copy that has already been marked for deletion.

llvm-svn: 102027

Author: Evan Cheng

llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp

@@ -804,7 +804,8 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
           CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
         // If the use is a copy and it won't be coalesced away, and its source
         // is defined by a trivial computation, try to rematerialize it instead.
-        if (ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,
+        if (!JoinedCopies.count(UseMI) &&
+            ReMaterializeTrivialDef(li_->getInterval(SrcReg), CopyDstReg,
                                     CopyDstSubIdx, UseMI))
           continue;
       }

llvm/test/CodeGen/X86/2010-04-21-CoalescerBug.ll

@@ -0,0 +1,15 @@
+; RUN: llc < %s -mtriple=x86_64-apple-darwin
+; rdar://7886733
+
+%struct.CMTime = type <{ i64, i32, i32, i64 }>
+%struct.CMTimeMapping = type { %struct.CMTimeRange, %struct.CMTimeRange }
+%struct.CMTimeRange = type { %struct.CMTime, %struct.CMTime }
+
+define void @t(%struct.CMTimeMapping* noalias nocapture sret %agg.result) nounwind optsize ssp {
+entry:
+  %agg.result1 = bitcast %struct.CMTimeMapping* %agg.result to i8* ; <i8*> [#uses=1]
+  tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %agg.result1, i8* null, i64 96, i32 4, i1 false)
+  ret void
+}
+
+declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind