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author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-09-22 21:39:34 +0000 |
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committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-09-22 21:39:34 +0000 |
commit | 08f5cdf5b33b8202edddb24abee6af2a0b3ae49c (patch) | |
tree | 7f10f65f263a2d916cb4e5032ebb0048c4b5bb7a /lib/CodeGen/SelectionDAG/InstrEmitter.cpp | |
parent | 91fb536a345dc268e5b73dbddb9bee4cba87b28f (diff) | |
download | external_llvm-08f5cdf5b33b8202edddb24abee6af2a0b3ae49c.zip external_llvm-08f5cdf5b33b8202edddb24abee6af2a0b3ae49c.tar.gz external_llvm-08f5cdf5b33b8202edddb24abee6af2a0b3ae49c.tar.bz2 |
Constrain register classes instead of emitting copies.
Sometimes register class constraints are trivial, like GR32->GR32_NOSP,
or GPR->rGPR. Teach InstrEmitter to simply constrain the virtual
register instead of emitting a copy in these cases.
Normally, these copies are handled by the coalescer. This saves some
coalescer work.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140340 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG/InstrEmitter.cpp')
-rw-r--r-- | lib/CodeGen/SelectionDAG/InstrEmitter.cpp | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp index 000a7df..b0239e1 100644 --- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp +++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp @@ -280,15 +280,17 @@ InstrEmitter::AddRegisterOperand(MachineInstr *MI, SDValue Op, MCID.OpInfo[IIOpNum].isOptionalDef(); // If the instruction requires a register in a different class, create - // a new virtual register and copy the value into it. + // a new virtual register and copy the value into it, but first attempt to + // shrink VReg's register class within reason. For example, if VReg == GR32 + // and II requires a GR32_NOSP, just constrain VReg to GR32_NOSP. + const unsigned MinRCSize = 4; if (II) { - const TargetRegisterClass *SrcRC = MRI->getRegClass(VReg); const TargetRegisterClass *DstRC = 0; if (IIOpNum < II->getNumOperands()) DstRC = TII->getRegClass(*II, IIOpNum, TRI); assert((DstRC || (MCID.isVariadic() && IIOpNum >= MCID.getNumOperands())) && "Don't have operand info for this instruction!"); - if (DstRC && !SrcRC->hasSuperClassEq(DstRC)) { + if (DstRC && !MRI->constrainRegClass(VReg, DstRC, MinRCSize)) { unsigned NewVReg = MRI->createVirtualRegister(DstRC); BuildMI(*MBB, InsertPos, Op.getNode()->getDebugLoc(), TII->get(TargetOpcode::COPY), NewVReg).addReg(VReg); |