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author | Dan Gohman <gohman@apple.com> | 2008-10-02 14:56:12 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2008-10-02 14:56:12 +0000 |
commit | 5bbee4b40a90f2825e229ed0f1d2b7b1ee7cd361 (patch) | |
tree | d1fa74fca8ef309b6c54fe6e1123738b64135285 /lib | |
parent | 5e249b4a14a1553039de338e5e50a1656605a7ea (diff) | |
download | external_llvm-5bbee4b40a90f2825e229ed0f1d2b7b1ee7cd361.zip external_llvm-5bbee4b40a90f2825e229ed0f1d2b7b1ee7cd361.tar.gz external_llvm-5bbee4b40a90f2825e229ed0f1d2b7b1ee7cd361.tar.bz2 |
Work around an interaction between fast-isel and regalloc=local. The
local register allocator's physreg liveness doesn't recognize subregs,
so it doesn't know that defs of %ecx that are immediately followed by
uses of %cl aren't dead. This comes up due to the way fast-isel emits
shift instructions.
This is a temporary workaround. Arguably, local regalloc should
handle subreg references correctly. On the other hand, perhaps
fast-isel should use INSERT_SUBREG instead of just assigning to the
most convenient super-register of %cl when lowering shifts.
This fixes MultiSource/Benchmarks/MallocBench/espresso,
MultiSource/Applications/hexxagon, and others, under -fast.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56947 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/Target/X86/X86FastISel.cpp | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp index 59500ad..3d57590 100644 --- a/lib/Target/X86/X86FastISel.cpp +++ b/lib/Target/X86/X86FastISel.cpp @@ -741,7 +741,11 @@ bool X86FastISel::X86SelectShift(Instruction *I) { if (Op1Reg == 0) return false; TII.copyRegToReg(*MBB, MBB->end(), CReg, Op1Reg, RC, RC); unsigned ResultReg = createResultReg(RC); - BuildMI(MBB, TII.get(OpReg), ResultReg).addReg(Op0Reg); + BuildMI(MBB, TII.get(OpReg), ResultReg).addReg(Op0Reg) + // FIXME: The "Local" register allocator's physreg liveness doesn't + // recognize subregs. Adding the superreg of CL that's actually defined + // prevents it from being re-allocated for this instruction. + .addReg(CReg, false, true); UpdateValueMap(I, ResultReg); return true; } |