From c662d06e261d53829bc842324a0c13f09b8e8784 Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Wed, 1 Mar 2017 21:06:18 +0000 Subject: [PATCH] [APInt] Optimize APInt creation from uint64_t Summary: This patch moves the clearUnusedBits calls into the two different initialization paths for APInt from a uint64_t. This allows the compiler to better optimize the clearing of the unused bits for the single word case. And it puts the clearing for the multi word case into the initSlowCase function to save code. In the common case of initializing with 0 this allows the clearing to be completely optimized out for the single word case. On my local x86 build this is showing a ~45kb reduction in the size of the opt binary. Reviewers: RKSimon, hans, majnemer, davide, MatzeB Reviewed By: hans Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D30486 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296677 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/ADT/APInt.h | 7 ++++--- lib/Support/APInt.cpp | 1 + 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h index 2af3aabe188..2acb60f769d 100644 --- a/include/llvm/ADT/APInt.h +++ b/include/llvm/ADT/APInt.h @@ -240,11 +240,12 @@ public: APInt(unsigned numBits, uint64_t val, bool isSigned = false) : BitWidth(numBits), VAL(0) { assert(BitWidth && "bitwidth too small"); - if (isSingleWord()) + if (isSingleWord()) { VAL = val; - else + clearUnusedBits(); + } else { initSlowCase(val, isSigned); - clearUnusedBits(); + } } /// \brief Construct an APInt of numBits width, initialized as bigVal[]. diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp index 10124fabaec..836498e6c0e 100644 --- a/lib/Support/APInt.cpp +++ b/lib/Support/APInt.cpp @@ -81,6 +81,7 @@ void APInt::initSlowCase(uint64_t val, bool isSigned) { if (isSigned && int64_t(val) < 0) for (unsigned i = 1; i < getNumWords(); ++i) pVal[i] = -1ULL; + clearUnusedBits(); } void APInt::initSlowCase(const APInt& that) { -- 2.50.1