[PATCH] D152754: [PowerPC] Correct missue of getOperandConstraint in PPCInstrInfo::commuteInstructionImpl

[Craig Topper via Phabricator via llvm-commits]

craig.topper created this revision.
craig.topper added a reviewer: nemanjai.
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getOperandConstraint does not return a bool, it returns an int. It
returns -1 if there is no TIED_TO.

Additionally, TIED_TO is only set on use operands not defs and it
points to the def that the use is tied to. So calling it on operand 0
is guaranteed to return -1.

As far as I can tell this code must have been copied from the
generic implementation prior to 6aa2744bed0b8.o

Unfortunately, this code is not executed in lit tests. I just happened
to notice it while looking for other uses of TIED_TO for something
I was working on.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D152754

Files:
  llvm/lib/Target/PowerPC/PPCInstrInfo.cpp


Index: llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1175,7 +1175,7 @@
   // destination register as well.
   if (Reg0 == Reg1) {
     // Must be two address instruction!
-    assert(MI.getDesc().getOperandConstraint(0, MCOI::TIED_TO) &&
+    assert(MI.getDesc().getOperandConstraint(1, MCOI::TIED_TO) == 0 &&
            "Expecting a two-address instruction!");
     assert(MI.getOperand(0).getSubReg() == SubReg1 && "Tied subreg mismatch");
     Reg2IsKill = false;


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