[PATCH] Constant fold llvm.expect(c, ...) -> c

Chandler Carruth chandlerc at google.com
Mon Jan 26 10:24:20 PST 2015

On Sun, Jan 25, 2015 at 9:37 PM, Pete Cooper <peter_cooper at apple.com> wrote:

> Hi hfinkel,
> This teaches the constant folder that an llvm.expect intrinsic with a
> constant as the first operand will return that constant.
> This reduces the size of an LTO'd llc by over 1% due to branches which can
> be removed once the constant is propagated.

I really don't understand this.

The design llvm.expect was specifically for LowerExpect to remove *all* of
these intrinsics from the IR? Why isn't that working?
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