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...tDivCheap() decision. > > In visitSDIV(), checking looks like this when the denominator is a power of 2. > > if (TLI.isIntDivCheap(N->getValueType(0), MinSize)) > return SDValue(); > > // Target-specific implementation of sdiv x, pow2. > if (SDValue Res = BuildSDIVPow2(N)) > return Res; > > How about this for isIntDivCheap? > 1) pass Function* to allow the target to decide for itself which > attributes matter, and If you want the attributes, I think you should pass the attributes and not the whole Function. I’m not sure why MinSize does not...

...AG.getConstant(lg2, DL, > getShiftAmountTy(ADD.getValueType()))); > > And there’s already a target-specific hook to add a custom implementation (e.g. on PowerPC): > > // Target-specific implementation of sdiv x, pow2. > if (SDValue Res = BuildSDIVPow2(N)) > return Res; Isn’t the problem the fact that the patch makes it harder for a target to get the generic code to reach its custom hook? Now the "cheap pow2 sdiv” is merged with the generic “cheap div” you can’t distinguish anymore. — Mehdi -------------- next part ------------...

Hello LLVM, A recent commit creates the isIntDivCheap() target query. http://reviews.llvm.org/D12082 The current approach has a couple shortcomings. First, when targets decide divide is cheap, the DAGCombiner ignores obvious power-of-2 optimizations. In the targets I know, shifts are cheaper than divides in both speed and size. The target cannot see the value in the isIntDivCheap() call, so

...V(), checking looks like this when the denominator is a power of 2. >>> >>> if (TLI.isIntDivCheap(N->getValueType(0), MinSize)) >>> return SDValue(); >>> >>> // Target-specific implementation of sdiv x, pow2. >>> if (SDValue Res = BuildSDIVPow2(N)) >>> return Res; >>> >>> How about this for isIntDivCheap? >>> 1) pass Function* to allow the target to decide for itself which >>> attributes matter, and >> >> If you want the attributes, I think you should pass the attributes and n...