Revert "[GVNSink] Fix incorrect codegen with respect to GEPs #85333" (#90658)

Reverts #88440

Test failing on Windows:
https://lab.llvm.org/buildbot/#/builders/233/builds/9396
```
Input file: <stdin>
# | Check file: C:\buildbot\as-builder-8\llvm-nvptx-nvidia-win\llvm-project\llvm\test\Transforms\GVNSink\different-gep-types.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            .
# |            .
# |            .
# |           42:  br label %if.end6 
# |           43:  
# |           44: if.else5: ; preds = %if.else 
# |           45:  br label %if.end6 
# |           46:  
# |           47: if.end6: ; preds = %if.else5, %if.then3, %if.then 
# | next:67'0             X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
# | next:67'1                                                        with "IF_THEN" equal to "%if\\.then"
# | next:67'2                                                        with "IF_THEN3" equal to "%if\\.then3"
# | next:67'3                                                        with "IF_ELSE5" equal to "%if\\.else5"
# |           48:  %.sink1 = phi i32 [ -8, %if.then3 ], [ -4, %if.else5 ], [ 8, %if.then ] 
# | next:67'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# | next:67'4      ?                                                                        possible intended match
# |           49:  %0 = load ptr, ptr %__i, align 4 
# | next:67'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           50:  %incdec.ptr4 = getelementptr inbounds i8, ptr %0, i32 %.sink1 
# | next:67'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           51:  store ptr %incdec.ptr4, ptr %__i, align 4 
# | next:67'0     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# |           52:  ret void 
# | next:67'0     ~~~~~~~~~~
# |           53: } 
# | next:67'0     ~~
# | >>>>>>
# `-----------------------------
# error: command failed with exit status: 1
```

Author: hiraditya

llvm/lib/Transforms/Scalar/GVNSink.cpp

@@ -719,11 +719,12 @@ GVNSink::analyzeInstructionForSinking(LockstepReverseIterator &LRI,
   // try and continue making progress.
   Instruction *I0 = NewInsts[0];
 
-  auto isNotSameOperation = [&I0](Instruction *I) {
-    return !I0->isSameOperationAs(I);
+  // If all instructions that are going to participate don't have the same
+  // number of operands, we can't do any useful PHI analysis for all operands.
+  auto hasDifferentNumOperands = [&I0](Instruction *I) {
+    return I->getNumOperands() != I0->getNumOperands();
   };
-
-  if (any_of(NewInsts, isNotSameOperation))
+  if (any_of(NewInsts, hasDifferentNumOperands))
     return std::nullopt;
 
   for (unsigned OpNum = 0, E = I0->getNumOperands(); OpNum != E; ++OpNum) {