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| author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-06-13 03:26:46 +0000 |
|---|---|---|
| committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-06-13 03:26:46 +0000 |
| commit | 5e5ed4457749995b46d46e9769e657fcc0818e2c (patch) | |
| tree | c97c95cd44a3fe2469a41fb69cf45e15125a20af /lib/CodeGen/RegAllocFast.cpp | |
| parent | 687397c01387534e98d2e8332d4b91536290d778 (diff) | |
| download | llvm-5e5ed4457749995b46d46e9769e657fcc0818e2c.tar.gz llvm-5e5ed4457749995b46d46e9769e657fcc0818e2c.tar.bz2 llvm-5e5ed4457749995b46d46e9769e657fcc0818e2c.tar.xz | |
Be less aggressive about hinting in RAFast.
In particular, don't spill dirty registers only to satisfy a hint. It is
not worth it.
The attached test case provides an example where the fast allocator
would spill a register when other registers are available.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132900 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/RegAllocFast.cpp')
| -rw-r--r-- | lib/CodeGen/RegAllocFast.cpp | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp index 97652036f9..65ebdf827d 100644 --- a/lib/CodeGen/RegAllocFast.cpp +++ b/lib/CodeGen/RegAllocFast.cpp @@ -487,14 +487,12 @@ void RAFast::allocVirtReg(MachineInstr *MI, LiveRegEntry &LRE, unsigned Hint) { // Take hint when possible. if (Hint) { - switch(calcSpillCost(Hint)) { - default: - definePhysReg(MI, Hint, regFree); - // Fall through. - case 0: + // Ignore the hint if we would have to spill a dirty register. + unsigned Cost = calcSpillCost(Hint); + if (Cost < spillDirty) { + if (Cost) + definePhysReg(MI, Hint, regFree); return assignVirtToPhysReg(LRE, Hint); - case spillImpossible: - break; } } |