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Diffstat (limited to 'lib/CodeGen/SimpleRegisterCoalescing.cpp')
| -rw-r--r-- | lib/CodeGen/SimpleRegisterCoalescing.cpp | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp index 7f36ef5bce..c5fe8c4986 100644 --- a/lib/CodeGen/SimpleRegisterCoalescing.cpp +++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp @@ -1731,7 +1731,20 @@ SimpleRegisterCoalescing::JoinIntervals(LiveInterval &LHS, LiveInterval &RHS, // If it's coalescing a virtual register to a physical register, estimate // its live interval length. This is the *cost* of scanning an entire live // interval. If the cost is low, we'll do an exhaustive check instead. + + // If this is something like this: + // BB1: + // v1024 = op + // ... + // BB2: + // ... + // RAX = v1024 + // + // That is, the live interval of v1024 crosses a bb. Then we can't rely on + // less conservative check. It's possible a sub-register is defined before + // v1024 (or live in) and live out of BB1. if (RHS.containsOneValue() && + li_->intervalIsInOneMBB(RHS) && li_->getApproximateInstructionCount(RHS) <= 10) { // Perform a more exhaustive check for some common cases. if (li_->conflictsWithPhysRegRef(RHS, LHS.reg, true, JoinedCopies)) |