[PATCH] CodeGen target hook for emitting intrinsic or libcall for pow*

John McCall rjmccall at apple.com
Wed Jul 10 11:26:24 PDT 2013

On Jul 10, 2013, at 11:18 AM, Eli Bendersky <eliben at google.com> wrote:
> On Wed, Jul 10, 2013 at 3:03 AM, John McCall <rjmccall at apple.com> wrote:
> On Jun 27, 2013, at 3:57 PM, Eli Bendersky <eliben at google.com> wrote:
> > Without fmath-errno, Clang currently generates calls to @llvm.pow.* intrinsics when it sees pow*(). This may not be suitable for all targets (for example PNaCl), so the attached patch adds a target hook that CodeGen queries. The target can state its preference for having or not having the intrinsic generated. Non-PNaCl behavior remains unchanged; PNaCl-specific test added.
> Isn't a more straightforward and less invasive approach to just invoke the compiler with -fno-builtin=pow or something along those lines?
> We don't control the flags users supply to Clang though. 

Then handle it in the driver.

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