diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index 7847f8ec20e..58763718f9b 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -2371,9 +2371,19 @@ namespace { struct DepthMBBCompare { typedef std::pair DepthMBBPair; bool operator()(const DepthMBBPair &LHS, const DepthMBBPair &RHS) const { - if (LHS.first > RHS.first) return true; // Deeper loops first - return LHS.first == RHS.first && - LHS.second->getNumber() < RHS.second->getNumber(); + // Deeper loops first + if (LHS.first != RHS.first) + return LHS.first > RHS.first; + + // Prefer blocks that are more connected in the CFG. This takes care of + // the most difficult copies first while intervals are short. + unsigned cl = LHS.second->pred_size() + LHS.second->succ_size(); + unsigned cr = RHS.second->pred_size() + RHS.second->succ_size(); + if (cl != cr) + return cl > cr; + + // As a last resort, sort by block number. + return LHS.second->getNumber() < RHS.second->getNumber(); } }; } diff --git a/test/CodeGen/X86/2009-09-19-SchedCustomLoweringBug.ll b/test/CodeGen/X86/2009-09-19-SchedCustomLoweringBug.ll index f3cf1d5e701..d372da33676 100644 --- a/test/CodeGen/X86/2009-09-19-SchedCustomLoweringBug.ll +++ b/test/CodeGen/X86/2009-09-19-SchedCustomLoweringBug.ll @@ -10,6 +10,7 @@ entry: bb: ; preds = %bb1, %entry ; CHECK: addl $1 +; CHECK-NEXT: movl %e ; CHECK-NEXT: adcl $0 %i.0 = phi i64 [ 0, %entry ], [ %0, %bb1 ] ; [#uses=1] %0 = add nsw i64 %i.0, 1 ; [#uses=2]