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author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2012-09-06 18:15:23 +0000 |
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committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2012-09-06 18:15:23 +0000 |
commit | 45c5c57179e8b4938042431f8e12c9bfad67b3c8 (patch) | |
tree | 028a8ab9a6720b6c1fe6c9b3a8b3eadbc531a428 /lib/CodeGen/LiveInterval.cpp | |
parent | e617ccb80da76821379bbff4a2fdcd09e8401e8b (diff) | |
download | llvm-45c5c57179e8b4938042431f8e12c9bfad67b3c8.tar.gz llvm-45c5c57179e8b4938042431f8e12c9bfad67b3c8.tar.bz2 llvm-45c5c57179e8b4938042431f8e12c9bfad67b3c8.tar.xz |
Allow overlaps between virtreg and physreg live ranges.
The RegisterCoalescer understands overlapping live ranges where one
register is defined as a copy of the other. With this change, register
allocators using LiveRegMatrix can do the same, at least for copies
between physical and virtual registers.
When a physreg is defined by a copy from a virtreg, allow those live
ranges to overlap:
%CL<def> = COPY %vreg11:sub_8bit; GR32_ABCD:%vreg11
%vreg13<def,tied1> = SAR32rCL %vreg13<tied0>, %CL<imp-use,kill>
We can assign %vreg11 to %ECX, overlapping the live range of %CL.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163336 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/LiveInterval.cpp')
-rw-r--r-- | lib/CodeGen/LiveInterval.cpp | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp index 0a795e644c..50e181cba8 100644 --- a/lib/CodeGen/LiveInterval.cpp +++ b/lib/CodeGen/LiveInterval.cpp @@ -27,6 +27,7 @@ #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetRegisterInfo.h" +#include "RegisterCoalescer.h" #include <algorithm> using namespace llvm; @@ -142,6 +143,48 @@ bool LiveInterval::overlapsFrom(const LiveInterval& other, return false; } +bool LiveInterval::overlaps(const LiveInterval &Other, + const CoalescerPair &CP, + const SlotIndexes &Indexes) const { + assert(!empty() && "empty interval"); + if (Other.empty()) + return false; + + // Use binary searches to find initial positions. + const_iterator I = find(Other.beginIndex()); + const_iterator IE = end(); + if (I == IE) + return false; + const_iterator J = Other.find(I->start); + const_iterator JE = Other.end(); + if (J == JE) + return false; + + for (;;) { + // J has just been advanced to satisfy: + assert(J->end >= I->start); + // Check for an overlap. + if (J->start < I->end) { + // I and J are overlapping. Find the later start. + SlotIndex Def = std::max(I->start, J->start); + // Allow the overlap if Def is a coalescable copy. + if (Def.isBlock() || + !CP.isCoalescable(Indexes.getInstructionFromIndex(Def))) + return true; + } + // Advance the iterator that ends first to check for more overlaps. + if (J->end > I->end) { + std::swap(I, J); + std::swap(IE, JE); + } + // Advance J until J->end >= I->start. + do + if (++J == JE) + return false; + while (J->end < I->start); + } +} + /// overlaps - Return true if the live interval overlaps a range specified /// by [Start, End). bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const { |