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authormycroft <mycroft@NetBSD.org>2003-10-29 21:25:03 +0000
committermycroft <mycroft@NetBSD.org>2003-10-29 21:25:03 +0000
commitb9c785bd44c820ea2b82f64ba0897c0451fc418c (patch)
tree8b7be2fd25f7483e60ee4d4c069b29afc88b72ed /sys/dev
parent5eb21a140e16ae31fd18056b7923f70bc3a257a3 (diff)
As seen on tech-toolchain:
So the problem is thus: * The {u,}mulsidi3 generate two parallel sets which modify the upper and lower halves of the target register. * life_analysis() does not track subregister modifications -- if you don't modify the whole register with a single set, it considers the register unused. The simple, if klugy, solution to this is to stick an explicit clobber in. It seems to work. While doing this, I noticed that constant folding was not happening for 32x32->64 multiplies. This is because the parallel set generated by {u,}mulsidi3 cannot be folded at all. To solve this, I first expand to a normal multiply, and then use a define_insn_and_split to convert it to the parallel set after CSE and constant folding. This patch has also been submitted to GCC bugzilla, but who knows if I'll get a reply to that.
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