[llvm] [GlobalISel] Make sure to check for load barriers when merging G_EXTRACT_VECTOR_ELT into G_LOAD. (PR #82306)

[Owen Anderson via llvm-commits]

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@@ -1198,6 +1198,18 @@ bool CombinerHelper::matchCombineExtractedVectorLoad(MachineInstr &MI,
   if (!VecEltTy.isByteSized())
     return false;
 
+  // Check for load fold barriers between the extraction and the load.
+  if (MI.getParent() != LoadMI->getParent())
+    return false;
+  const unsigned MaxIter = 20;
+  unsigned Iter = 0;
+  for (auto II = LoadMI->getIterator(), IE = MI.getIterator(); II != IE; ++II) {
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resistor wrote:

I'm not aware of an option.

https://github.com/llvm/llvm-project/pull/82306