[PATCH] D26569: [InstCombine] Support load(gep(A, select(idx1, idx2)))) to select(load(gep(A, idx1)), load(gep(A, idx2))) transformation

[David Majnemer via llvm-commits]

majnemer added inline comments.


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Comment at: lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp:886
+    Value *LastOp = GEPI->getOperand(LastIdx);
+    if (SelectInst *SI = dyn_cast<SelectInst>(LastOp)) {
+      GetElementPtrInst *NewGEP1 = cast<GetElementPtrInst>(GEPI->clone());
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`auto *SI`


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Comment at: lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp:907-908
+      } else {
+        delete NewGEP1;
+        delete NewGEP2;
+      }
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Do not create IR if you don't think you will use it.


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Comment at: test/Transforms/InstCombine/load-gep-select.ll:1
+; RUN: opt -instcombine -gvn -S < %s | FileCheck %s
+; PR30950. Check instcombine supports the transformation of load(gep(A, select(I1, I2))) ==> select(load(gep(A, I1)), load(gep(A, I2))), so that global value numbering can remove the redundent loads.
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I'm not sure how I feel about two different passes showing up here.


Repository:
  rL LLVM

https://reviews.llvm.org/D26569