[WebAssembly] Add TargetInstrInfo::getCalleeOperand

DwarfDebug unconditionally assumes for all call instructions the 0th
operand is the callee operand, which seems to be true for other targets,
but not for WebAssembly. This adds `TargetInstrInfo::getCallOperand`
method whose default implementation returns `getOperand(0)` and makes
WebAssembly overrides it to use its own utility method to get the callee
operand.

This also fixes an existing bug in `WebAssembly::getCalleeOp`, which was
uncovered by this CL.

Reviewed By: dschuff, djtodoro

Differential Revision: https://reviews.llvm.org/D102978

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/WebAssembly/Utils/WebAssemblyUtilities.cpp b/llvm/lib/Target/WebAssembly/Utils/WebAssemblyUtilities.cpp
index b9344bb..824d336 100644
--- a/llvm/lib/Target/WebAssembly/Utils/WebAssemblyUtilities.cpp
+++ b/llvm/lib/Target/WebAssembly/Utils/WebAssemblyUtilities.cpp
@@ -91,7 +91,7 @@ const MachineOperand &WebAssembly::getCalleeOp(const MachineInstr &MI) {
   case WebAssembly::CALL_INDIRECT_S:
   case WebAssembly::RET_CALL_INDIRECT:
   case WebAssembly::RET_CALL_INDIRECT_S:
-    return MI.getOperand(MI.getNumOperands() - 1);
+    return MI.getOperand(MI.getNumExplicitOperands() - 1);
   default:
     llvm_unreachable("Not a call instruction");
   }