ScheduleDAG.cpp patch: error message more meaningful.

[llvmbot]

Bugzilla Link	1184
Resolution	FIXED
Resolved on	Feb 22, 2010 12:41
Version	trunk
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

Small patch to make tracking down (self-inflicted) bugs easier when the
scheduler barfs. The assert() wasn't really helpful at all. At least this patch
tells you which instruction and operand to go look at.

(Note: In the end, yes, it was my fault, but this patch actually helped.)

Index: lib/CodeGen/SelectionDAG/ScheduleDAG.cpp

--- lib/CodeGen/SelectionDAG/ScheduleDAG.cpp (revision 522)
+++ lib/CodeGen/SelectionDAG/ScheduleDAG.cpp (working copy)
@@ -301,9 +301,20 @@
if (II) {
const TargetRegisterClass *RC =
getInstrOperandRegClass(MRI, TII, II, IIOpNum);

•  const TargetRegisterClass *VRC = RegMap->getRegClass(VReg);
   assert(RC && "Don't have operand info for this instruction!");
  

•  assert(RegMap->getRegClass(VReg) == RC &&
  

•         "Register class of operand and regclass of use don't agree!");
  

•  if (VRC != RC) {
  

•   cerr << "Register class of operand and regclass of use don't agree!\n";
  

•   cerr << "Operand = " << IIOpNum << "\n";
  

•   cerr << "Op->Val = "; Op.Val->dump(0); cerr << "\n";
  

•   cerr << "MI = "; MI->print(cerr);
  

•   cerr << "VReg = " << VReg << "\n";
  

•   cerr << "VReg RegClass     size = " << VRC->getSize()
  

•        << ", align = " << VRC->getAlignment() << "\n";
  

•   cerr << "Expected RegClass size = " << RC->getSize()
  

•        << ", align = " << RC->getAlignment() << "\n";
  

•   abort();
  

•  }
  

  }
  } else if (ConstantSDNode *C =
  dyn_cast(Op)) {

[llvmbot]

Scott,

You have a "dump" in there so that entire block needs to be debug guarded.
Please wrap it in

#ifndef NDEBUG
...
#endif

including the VRC definition .. its only needed in debug builds.

[llvmbot]

Hmm .. actually, you're replacing the assert .. its fine :)

[llvmbot]

One would think the author of the build system would have this stuff straight.
Unfortunately, I need to recant. NDEBUG is set when assertions are turned off so
the code does need to be wrapped in:

#ifndef NDEBUG
...
#endif

Sorry for the confusion.

Better still, figure out how to handle the VRC != RC case :)

[llvmbot]

Resubmitted patch with Reid's suggestions.

[llvmbot]

Updated (with NDEBUG) patch
Addresses Reid's comments regarding non-debug builds (although, wouldn't you
want to know if this bug showed up). The compromise is to print info only if
NDEBUG isn't set.

[lattner]

I applied your patch. Please make sure not to use tabs though :)
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070212/044578.html

-Chris