[PATCH] D155790: PreISelIntrinsicLowering: don't expand memcpys in minsize functions, even with no-builtins.

[Amara Emerson via Phabricator via llvm-commits]

aemerson added inline comments.


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Comment at: llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp:201
+    // so just avoid expanding here if the caller is a minsize function.
+    bool IsMinSize = Inst->getFunction()->hasMinSize();
 
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arsenm wrote:
> Lowering the intrinsic when the libcall isn't available is mandatory, you can't simply skip it.
> 
> For minsize, you could adjust the default size threshold. Also, we could inject into the module an implementation you expand into, so the expansion happens fewer times
no-builtins is attached to the Function with -fno-builtins right? However the semantics of -fno-builtins is not AFAICT that we need to expand all memcpy intrinsics. The semantics are that clang shouldn't try to recognize things like memcpy loops and turn them into intrinsics. Or that plain memcpy calls shouldn't be converted into intrinsics.


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  https://reviews.llvm.org/D155790/new/

https://reviews.llvm.org/D155790