[PATCH] D19390: folding compares for distinct allocations

[David Majnemer via llvm-commits]

majnemer added inline comments.

================
Comment at: lib/Transforms/InstCombine/InstructionCombining.cpp:1905-1909
@@ -1902,2 +1904,7 @@
         unsigned OtherIndex = (ICI->getOperand(0) == PI) ? 1 : 0;
-        if (!isNeverEqualToUnescapedAlloc(ICI->getOperand(OtherIndex)))
+        // We avoid the case of allocation being compared to itself.
+        // Strip off pointer and zero GEPs
+        if (PI ==
+                ICI->getOperand(OtherIndex)
+                    ->stripPointerCastsNoFollowAliases() ||
+            !isNeverEqualToUnescapedAlloc(ICI->getOperand(OtherIndex), TLI))
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I don't think this will do the right thing if `%x = allocation` is compared with `gep(gep(%x, 1), -1)`.


http://reviews.llvm.org/D19390