From 7e3e7afca87f5bbd6ce416e483b26c36ea384ecf Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Sun, 7 May 2017 22:22:11 +0000 Subject: [ConstantRange][SimplifyCFG] Add a helper method to allow SimplifyCFG to determine if a ConstantRange has more than 8 elements without requiring an allocation if the ConstantRange is 64-bits wide. Previously SimplifyCFG used getSetSize which returns an APInt that is 1 bit wider than the ConstantRange's bit width. In the reasonably common case that the ConstantRange is 64-bits wide, this requires returning a 65-bit APInt. APInt's can only store 64-bits without a memory allocation so this is inefficient. The new method takes the 8 as an input and tells if the range contains more than that many elements without requiring any wider math. llvm-svn: 302385 --- llvm/lib/IR/ConstantRange.cpp | 11 +++++++++++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp | 2 +- 2 files changed, 12 insertions(+), 1 deletion(-) (limited to 'llvm/lib') diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp index cb703f6efc6..aeb1257754f 100644 --- a/llvm/lib/IR/ConstantRange.cpp +++ b/llvm/lib/IR/ConstantRange.cpp @@ -260,6 +260,17 @@ ConstantRange::isSizeStrictlySmallerThan(const ConstantRange &Other) const { return (Upper - Lower).ult(Other.Upper - Other.Lower); } +bool +ConstantRange::isSizeLargerThan(uint64_t MaxSize) const { + assert(MaxSize && "MaxSize can't be 0."); + // If this a full set, we need special handling to avoid needing an extra bit + // to represent the size. + if (isFullSet()) + return APInt::getMaxValue(getBitWidth()).ugt(MaxSize - 1); + + return (Upper - Lower).ugt(MaxSize); +} + APInt ConstantRange::getUnsignedMax() const { if (isFullSet() || isWrappedSet()) return APInt::getMaxValue(getBitWidth()); diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp index 7a3e8b9ae91..b44bc74d655 100644 --- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp +++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp @@ -596,7 +596,7 @@ private: Span = Span.inverse(); // If there are a ton of values, we don't want to make a ginormous switch. - if (Span.getSetSize().ugt(8) || Span.isEmptySet()) { + if (Span.isSizeLargerThan(8) || Span.isEmptySet()) { return false; } -- cgit v1.2.3