Summary:
This patch adds udiv/sdiv/urem/srem/udivrem/sdivrem methods that can divide by a uint64_t. This makes division consistent with all the other arithmetic operations.
This modifies the interface of the divide helper method to work on raw arrays instead of APInts. This way we can pass the uint64_t in for the RHS without wrapping it in an APInt. This required moving all the Quotient and Remainder allocation handling up to the callers. For udiv/urem this was as simple as just creating the Quotient/Remainder with the right size when they were declared. For udivrem we have to rely on reallocate not changing the contents of the variable LHS or RHS is aliased with the Quotient or Remainder APInts. We also have to zero the upper bits of Remainder and Quotient that divide doesn't write to if lhsWords/rhsWords is smaller than the width.
I've update the toString method to use the new udivrem.
Reviewers: hans, dblaikie, RKSimon
Reviewed By: RKSimon
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33310
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This helped the compiler generate better code for the single word case. It was able to remember that the bit width was still a single word when it created the Remainder APInt and not create code for it possibly being multiword.
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At this point in the code rhsWords is guaranteed to be non-zero and less than or equal to lhsWords. So if lhsWords is 1, rhsWords must also be 1. urem alread had the check removed so this makes all 3 consistent.
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Summary:
This adds a resize method to APInt that manages deleting/allocating storage for an APInt and changes its bit width. Use this to simplify code in copy assignment and divide.
The assignment code in particular was overly complicated. Treating every possible case as a separate implementation. I'm also pretty sure the clearUnusedBits code at the end was unnecessary. Since we always copying whole words from the source APInt. All unused bits should be clear in the source.
Reviewers: hans, RKSimon
Reviewed By: RKSimon
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33073
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Turns out udivrem can write its output to the same location as one of its inputs so the extra temporary isn't needed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302772 91177308-0d34-0410-b5e6-96231b3b80d8
This lets toString take advantage of the degenerate case checks in udivrem and is just generally cleaner.
One minor downside of this is that the divisor APInt now needs to be the same size as Tmp which requires an additional allocation. But we were doing a poor job of reusing allocations before so the new code should still be an improvement.
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The description says it returns the number of words needed to represent the results. But the way it was coded it always returns (lhsWords + rhsWords) or (lhsWords + rhsWords - 1). But the result could be even smaller than that and it wouldn't tell you.
No one uses the result today so rather than try to fix it, just remove it.
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The value of 'i' is always the smaller of DstParts and SrcParts so we can just use that fact to write all the code in terms of SrcParts and DstParts.
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Currently multiply is implemented in operator*=. Operator* makes a copy and uses operator*= to modify the copy.
Operator*= itself allocates a temporary buffer to hold the multiply result as it computes it. Then copies it to the buffer in *this.
Operator*= attempts to bound the size of the result based on the number of active bits in its inputs. It also has a couple special cases to handle 0 inputs without any memory allocations or multiply operations. The best case is that it calculates a single word regardless of input bit width. The worst case is that it calculates the a 2x input width result and drop the upper bits.
Since operator* uses operator*= it incurs two allocations, one for a copy of *this and one for the temporary allocation. Neither of these allocations are kept after the method operation is done.
The main usage in the backend appears to be ConstantRange::multiply which uses operator* rather than operator*=.
This patch moves the multiply operation to operator* and implements operator*= using it. This avoids the copy in operator*. operator* now allocates a result buffer sized the same width as its inputs no matter what. This buffer will be used as the buffer for the returned APInt. Finally, we reuse tcMultiply to implement the multiply operation. This function is capable of not calculating additional upper words that will be discarded.
This change does lose the special optimizations for the inputs using less words than their size implies. But it also removed the getActiveBits calls from all multiplies. If we think those optimizations are important we could look at providing additional bounds to tcMultiply to limit the computations.
Differential Revision: https://reviews.llvm.org/D32830
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Currently several places assume the VAL member is always at least the same size as pVal. In particular for a memcpy in the move assignment operator. While this is a true assumption, it isn't good practice to assume this.
This patch gives the union a name so we can write the memcpy in terms of the union itself. This also adds a similar memcpy to the move constructor where we previously just copied using VAL directly.
This patch is mostly just a mechanical addition of the U in front of VAL and pVAL everywhere. But several constructors had to be modified since we can't directly initializer a field of named union from the initializer list.
Differential Revision: https://reviews.llvm.org/D30629
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This replaces a hand written copy loop with a call to memcpy for both zext and sext.
For sext, it replaces multiple if/else blocks propagating sign information forward. Now we just do a copy, a sign extension on the last copied word, a memset, and clearUnusedBits.
Differential Revision: https://reviews.llvm.org/D32417
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This patch adds an in place version of ashr to match lshr and shl which were recently added.
I've tried to make this similar to the lshr code with additions to handle the sign extension. I've also tried to do this with less if checks than the current ashr code by sign extending the original result to a word boundary before doing any of the shifting. This removes a lot of the complexity of determining where to fill in sign bits after the shifting.
Differential Revision: https://reviews.llvm.org/D32415
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Previously single word would always return 0 regardless of the original sign. Multi word would return all 0s or all 1s based on the original sign. Now single word takes into account the sign as well.
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The current code is trying to be clever with shifts to avoid needing to clear unused bits. But it looks like the compiler is unable to optimize out the unused bit handling in the APInt constructor. Given this its better to just use SignExtend64 and have more readable code.
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This reverts commit r301105, 4, 3 and 1, as a follow up of the previous
revert, which broke even more bots.
For reference:
Revert "[APInt] Use operator<<= where possible. NFC"
Revert "[APInt] Use operator<<= instead of shl where possible. NFC"
Revert "[APInt] Use ashInPlace where possible."
PR32754.
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For single word, shift by BitWidth was always returning 0, but for multiword it was based on original sign. Now single word matches multi word.
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The unused upper bits are guaranteed to be 0 so we don't need to worry about accidentally counting them.
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Currently sle and ule have to call slt/ult and eq to get the proper answer. This results in extra code for both calls and additional scans of multiword APInts.
This patch replaces slt/ult with a compareSigned/compare that can return -1, 0, or 1 so we can cover all the comparison functions with a single call.
While I was there I removed the activeBits calls and other checks at the start of the slow part of ult. Both of the activeBits calls potentially scan through each of the APInts separately. I can't imagine that's any better than just scanning them in parallel and doing the compares. Now we just share the code with tcCompare.
These changes seem to be good for about a 7-8k reduction on the size of the opt binary on my local x86-64 build.
Differential Revision: https://reviews.llvm.org/D32339
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This question comes up in many places in SimplifyDemandedBits. This makes it easy to ask without allocating additional temporary APInts.
The BitVector class provides a similar functionality through its (IMHO badly named) test(const BitVector&) method. Though its output polarity is reversed.
I've provided one example use case in this patch. I plan to do more as a follow up.
Differential Revision: https://reviews.llvm.org/D32258
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300851 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: This is a simple question we should be able to answer without creating a temporary to hold the AND result. We can also get an early out as soon as we find a word that intersects.
Reviewers: RKSimon, hans, spatel, davide
Reviewed By: hans, davide
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32253
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300812 91177308-0d34-0410-b5e6-96231b3b80d8
