diff options
| -rw-r--r-- | lib/Target/PowerPC/PPCISelLowering.cpp | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp index afb0c7e260..18404fcfef 100644 --- a/lib/Target/PowerPC/PPCISelLowering.cpp +++ b/lib/Target/PowerPC/PPCISelLowering.cpp @@ -2203,8 +2203,30 @@ SDOperand PPCTargetLowering::PerformDAGCombine(SDNode *N, break; } - // If there are non-zero uses of the flag value, use the VCMPo node! - if (VCMPoNode && !VCMPoNode->hasNUsesOfValue(0, 1)) + // If there is no VCMPo node, or if the flag value has a single use, don't + // transform this. + if (!VCMPoNode || VCMPoNode->hasNUsesOfValue(0, 1)) + break; + + // Look at the (necessarily single) use of the flag value. If it has a + // chain, this transformation is more complex. Note that multiple things + // could use the value result, which we should ignore. + SDNode *FlagUser = 0; + for (SDNode::use_iterator UI = VCMPoNode->use_begin(); + FlagUser == 0; ++UI) { + assert(UI != VCMPoNode->use_end() && "Didn't find user!"); + SDNode *User = *UI; + for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) { + if (User->getOperand(i) == SDOperand(VCMPoNode, 1)) { + FlagUser = User; + break; + } + } + } + + // If the user is a MFCR instruction, we know this is safe. Otherwise we + // give up for right now. + if (FlagUser->getOpcode() == PPCISD::MFCR) return SDOperand(VCMPoNode, 0); } break; |