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author | Evan Cheng <evan.cheng@apple.com> | 2008-12-19 20:58:01 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2008-12-19 20:58:01 +0000 |
commit | 5379f412bc6ac6171f3bd73930197bfce88c2faa (patch) | |
tree | 255acf30b79f9f0173c042e7a9f638df376871b8 /include | |
parent | de8c611c089d4c6327721367f3ed23b496692478 (diff) | |
download | external_llvm-5379f412bc6ac6171f3bd73930197bfce88c2faa.zip external_llvm-5379f412bc6ac6171f3bd73930197bfce88c2faa.tar.gz external_llvm-5379f412bc6ac6171f3bd73930197bfce88c2faa.tar.bz2 |
Fix PR3149. If an early clobber def is a physical register and it is tied to an input operand, it effectively extends the live range of the physical register. Currently we do not have a good way to represent this.
172 %ECX<def> = MOV32rr %reg1039<kill>
180 INLINEASM <es:subl $5,$1
sbbl $3,$0>, 10, %EAX<def>, 14, %ECX<earlyclobber,def>, 9, %EAX<kill>,
36, <fi#0>, 1, %reg0, 0, 9, %ECX<kill>, 36, <fi#1>, 1, %reg0, 0
188 %EAX<def> = MOV32rr %EAX<kill>
196 %ECX<def> = MOV32rr %ECX<kill>
204 %ECX<def> = MOV32rr %ECX<kill>
212 %EAX<def> = MOV32rr %EAX<kill>
220 %EAX<def> = MOV32rr %EAX
228 %reg1039<def> = MOV32rr %ECX<kill>
The early clobber operand ties ECX input to the ECX def.
The live interval of ECX is represented as this:
%reg20,inf = [46,47:1)[174,230:0) 0@174-(230) 1@46-(47)
The right way to represent this is something like
%reg20,inf = [46,47:2)[174,182:1)[181:230:0) 0@174-(182) 1@181-230 @2@46-(47)
Of course that won't work since that means overlapping live ranges defined by two val#.
The workaround for now is to add a bit to val# which says the val# is redefined by a early clobber def somewhere. This prevents the move at 228 from being optimized away by SimpleRegisterCoalescing::AdjustCopiesBackFrom.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61259 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'include')
-rw-r--r-- | include/llvm/CodeGen/LiveInterval.h | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/include/llvm/CodeGen/LiveInterval.h b/include/llvm/CodeGen/LiveInterval.h index 7ef2489..4062480 100644 --- a/include/llvm/CodeGen/LiveInterval.h +++ b/include/llvm/CodeGen/LiveInterval.h @@ -38,16 +38,19 @@ namespace llvm { /// - or reg # of the definition if it's a stack slot liveinterval. /// copy - Copy iff val# is defined by a copy; zero otherwise. /// hasPHIKill - One or more of the kills are PHI nodes. + /// redefByEC - Re-defined by early clobber somewhere during the live range. /// kills - Instruction # of the kills. struct VNInfo { unsigned id; unsigned def; MachineInstr *copy; - bool hasPHIKill; + bool hasPHIKill : 1; + bool redefByEC : 1; SmallVector<unsigned, 4> kills; - VNInfo() : id(~1U), def(~1U), copy(0), hasPHIKill(false) {} + VNInfo() + : id(~1U), def(~1U), copy(0), hasPHIKill(false), redefByEC(false) {} VNInfo(unsigned i, unsigned d, MachineInstr *c) - : id(i), def(d), copy(c), hasPHIKill(false) {} + : id(i), def(d), copy(c), hasPHIKill(false), redefByEC(false) {} }; /// LiveRange structure - This represents a simple register range in the @@ -177,6 +180,7 @@ namespace llvm { DstValNo->def = SrcValNo->def; DstValNo->copy = SrcValNo->copy; DstValNo->hasPHIKill = SrcValNo->hasPHIKill; + DstValNo->redefByEC = SrcValNo->redefByEC; DstValNo->kills = SrcValNo->kills; } |