[llvm-commits] [llvm] r80105 - /llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp

[Dan Gohman]

Author: djg
Date: Wed Aug 26 11:06:11 2009
New Revision: 80105

URL: http://llvm.org/viewvc/llvm-project?rev=80105&view=rev
Log:
Add comments detailing a known bug, so that people writing other
backends don't use it as an example.

Modified:
    llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp

Modified: llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp?rev=80105&r1=80104&r2=80105&view=diff

==============================================================================
--- llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/PIC16/PIC16ISelLowering.cpp Wed Aug 26 11:06:11 2009
@@ -533,6 +533,10 @@
     SDValue SrcLo, SrcHi;
     GetExpandedParts(Src, DAG, SrcLo, SrcHi);
     SDValue ChainLo = Chain, ChainHi = Chain;
+    // FIXME: This makes unsafe assumptions. The Chain may be a TokenFactor
+    // created for an unrelated purpose, in which case it may not have
+    // exactly two operands. Also, even if it does have two operands, they
+    // may not be the low and high parts of an aligned load that was split.
     if (Chain.getOpcode() == ISD::TokenFactor) {
       ChainLo = Chain.getOperand(0);
       ChainHi = Chain.getOperand(1);
@@ -560,16 +564,19 @@
     GetExpandedParts(SrcHi, DAG, SrcHi1, SrcHi2);
 
     SDValue ChainLo = Chain, ChainHi = Chain;
+    // FIXME: This makes unsafe assumptions; see the FIXME above.
     if (Chain.getOpcode() == ISD::TokenFactor) {  
       ChainLo = Chain.getOperand(0);
       ChainHi = Chain.getOperand(1);
     }
     SDValue ChainLo1 = ChainLo, ChainLo2 = ChainLo, ChainHi1 = ChainHi,
             ChainHi2 = ChainHi;
+    // FIXME: This makes unsafe assumptions; see the FIXME above.
     if (ChainLo.getOpcode() == ISD::TokenFactor) {
       ChainLo1 = ChainLo.getOperand(0);
       ChainLo2 = ChainLo.getOperand(1);
     }
+    // FIXME: This makes unsafe assumptions; see the FIXME above.
     if (ChainHi.getOpcode() == ISD::TokenFactor) {
       ChainHi1 = ChainHi.getOperand(0);
       ChainHi2 = ChainHi.getOperand(1);
@@ -601,6 +608,7 @@
     SDValue SrcLo, SrcHi;
     GetExpandedParts(Src, DAG, SrcLo, SrcHi);
     SDValue ChainLo = Chain, ChainHi = Chain;
+    // FIXME: This makes unsafe assumptions; see the FIXME above.
     if (Chain.getOpcode() == ISD::TokenFactor) {
       ChainLo = Chain.getOperand(0);
       ChainHi = Chain.getOperand(1);