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author | Evan Cheng <evan.cheng@apple.com> | 2006-11-15 20:54:11 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2006-11-15 20:54:11 +0000 |
commit | 9a1956ae6ad2d4892afbc9f1b97d645d220b6d4a (patch) | |
tree | f39fa6288e22e51d348e228aa54b5cf0c30d163c /lib/CodeGen/LiveIntervalAnalysis.cpp | |
parent | a6c4c1eb90413986519c46f70222539dee39ffe9 (diff) | |
download | llvm-9a1956ae6ad2d4892afbc9f1b97d645d220b6d4a.tar.gz llvm-9a1956ae6ad2d4892afbc9f1b97d645d220b6d4a.tar.bz2 llvm-9a1956ae6ad2d4892afbc9f1b97d645d220b6d4a.tar.xz |
A register def can be partially dead when the whole register has use(s) but a subreg does not.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31760 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/LiveIntervalAnalysis.cpp')
-rw-r--r-- | lib/CodeGen/LiveIntervalAnalysis.cpp | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index 730ad23914..03f38602ae 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -575,7 +575,6 @@ void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB, // A physical register cannot be live across basic block, so its // lifetime must end somewhere in its defining basic block. DEBUG(std::cerr << "\t\tregister: "; printRegName(interval.reg)); - typedef LiveVariables::killed_iterator KillIter; unsigned baseIndex = MIIdx; unsigned start = getDefIndex(baseIndex); @@ -599,6 +598,14 @@ void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB, DEBUG(std::cerr << " killed"); end = getUseIndex(baseIndex) + 1; goto exit; + } else if (lv_->ModifiesRegister(mi, interval.reg)) { + // Another instruction redefines the register before it is ever read. + // Then the register is essentially dead at the instruction that defines + // it. Hence its interval is: + // [defSlot(def), defSlot(def)+1) + DEBUG(std::cerr << " dead"); + end = getDefIndex(start) + 1; + goto exit; } } |