[llvm] Decompose gep of complex type struct to its element type (PR #107848)

[via llvm-commits]

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@@ -1555,6 +1555,17 @@ bool GetElementPtrInst::hasAllConstantIndices() const {
   return true;
 }
 
+/// hasAllZeroIndicesExceptLast - Return true if all of the indices of this GEP
+/// are zero except the last indice.
+bool GetElementPtrInst::hasAllZeroIndicesExceptLast() const {
+  for (unsigned i = 1, e = getNumOperands() - 1; i != e; ++i) {
+    ConstantInt *Val = dyn_cast<ConstantInt>(getOperand(i));
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vfdff wrote:

Do you mean something like the following one ? 
```
define <4 x ptr> @decompose_complex_vector1(ptr %array, <4 x ptr> %baseptrs) {
  %val = load <4 x i32>, ptr %array, align 4
  %sextVal = sext <4 x i32> %val to <4 x i64>
  %arrayidx = getelementptr inbounds [10000 x %"class.std::__1::complex"], <4 x ptr> %baseptrs, <4 x i64> zeroinitializer, <4 x i64> %sextVal
  ret <4 x ptr> %arrayidx
}
```


https://github.com/llvm/llvm-project/pull/107848