[llvm] [InstCombine] Make foldCmpLoadFromIndexedGlobal more resiliant to non-array geps. (PR #150639)

[Nikita Popov via llvm-commits]

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@@ -127,21 +133,27 @@ Instruction *InstCombinerImpl::foldCmpLoadFromIndexedGlobal(
     return nullptr;
 
   // There are many forms of this optimization we can handle, for now, just do
-  // the simple index into a single-dimensional array.
+  // the simple index into a single-dimensional array or elements of equal size.
   //
-  // Require: GEP GV, 0, i {{, constant indices}}
-  if (GEP->getNumOperands() < 3 || !isa<ConstantInt>(GEP->getOperand(1)) ||
-      !cast<ConstantInt>(GEP->getOperand(1))->isZero() ||
-      isa<Constant>(GEP->getOperand(2)))
+  // Require: GEP [n x i8] GV, 0, Idx {{, constant indices}}
+  //      Or: GEP i8 GV, Idx
+
+  SmallVector<unsigned, 4> LaterIndices;
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nikic wrote:

Why move the declaration of LaterIndices?

https://github.com/llvm/llvm-project/pull/150639