[PATCH] D16337: [LibCallSimplifier] fold memset(malloc(x), 0, x) --> calloc(1, x)

[Sanjay Patel via llvm-commits]

spatel added a comment.

In http://reviews.llvm.org/D16337#331118, @mcrosier wrote:

> What happens if there's an intervening store to the malloc'ed memory?  (dumb I know.. but..)


Ah, good catch. I checked 'hasOneUse()' in an earlier draft of this to avoid that scenario, but then I noticed that the example in the bug report had that 'llvm.objectsize' and other uses between the malloc and memset, so I removed that condition. I need to find a way around that.


================
Comment at: lib/Transforms/Utils/SimplifyLibCalls.cpp:978
@@ +977,3 @@
+                             B, DL, TLI);
+  Malloc->replaceAllUsesWith(Calloc);
+  Malloc->eraseFromParent();
----------------
mcrosier wrote:
> Shouldn't you check that Calloc is non-null here?
Yes - that won't work if calloc doesn't exist for the target.


http://reviews.llvm.org/D16337