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Do not shrink wrap live interval in a mbb if it's livein any of its successor blocks. The mbb can be revisited again after all of the successors are processed.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58184 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-10-26 07:49:03 +00:00
parent ac1cfa09d7
commit aaf510c932
2 changed files with 57 additions and 6 deletions
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27
lib/CodeGen/PreAllocSplitting.cpp
View File

@ -122,7 +122,7 @@ namespace {
SmallVector<MachineOperand*, 4>&,
SmallPtrSet<MachineInstr*, 4>&);
void ShrinkWrapLiveInterval(VNInfo*, MachineBasicBlock*,
void ShrinkWrapLiveInterval(VNInfo*, MachineBasicBlock*, MachineBasicBlock*,
MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*, 8>&,
DenseMap<MachineBasicBlock*, SmallVector<MachineOperand*, 4> >&,
DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 4> >&,
@ -426,15 +426,29 @@ PreAllocSplitting::ShrinkWrapToLastUse(MachineBasicBlock *MBB,
/// chain to find the new 'kills' and shrink wrap the live interval to the
/// new kill indices.
void
PreAllocSplitting::ShrinkWrapLiveInterval(VNInfo *ValNo,
MachineBasicBlock *MBB, MachineBasicBlock *DefMBB,
PreAllocSplitting::ShrinkWrapLiveInterval(VNInfo *ValNo, MachineBasicBlock *MBB,
MachineBasicBlock *SuccMBB, MachineBasicBlock *DefMBB,
SmallPtrSet<MachineBasicBlock*, 8> &Visited,
DenseMap<MachineBasicBlock*, SmallVector<MachineOperand*, 4> > &Uses,
DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 4> > &UseMIs,
SmallVector<MachineBasicBlock*, 4> &UseMBBs) {
if (!Visited.insert(MBB))
if (Visited.count(MBB))
return;
// If live interval is live in another successor path, then we can't process
// this block. But we may able to do so after all the successors have been
// processed.
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
SE = MBB->succ_end(); SI != SE; ++SI) {
MachineBasicBlock *SMBB = *SI;
if (SMBB == SuccMBB)
continue;
if (CurrLI->liveAt(LIs->getMBBStartIdx(SMBB)))
return;
}
Visited.insert(MBB);
DenseMap<MachineBasicBlock*, SmallVector<MachineOperand*, 4> >::iterator
UMII = Uses.find(MBB);
if (UMII != Uses.end()) {
@ -480,7 +494,8 @@ PreAllocSplitting::ShrinkWrapLiveInterval(VNInfo *ValNo,
// Pred is the def bb and the def reaches other val#s, we must
// allow the value to be live out of the bb.
continue;
ShrinkWrapLiveInterval(ValNo, Pred, DefMBB, Visited, Uses, UseMIs, UseMBBs);
ShrinkWrapLiveInterval(ValNo, Pred, MBB, DefMBB, Visited,
Uses, UseMIs, UseMBBs);
}
return;
@ -622,7 +637,7 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
// Walk up the predecessor chains.
SmallPtrSet<MachineBasicBlock*, 8> Visited;
ShrinkWrapLiveInterval(ValNo, BarrierMBB, DefMBB, Visited,
ShrinkWrapLiveInterval(ValNo, BarrierMBB, NULL, DefMBB, Visited,
Uses, UseMIs, UseMBBs);
// Remove live range from barrier to the restore. FIXME: Find a better

36
test/CodeGen/X86/pre-split6.ll Normal file
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@ -0,0 +1,36 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split
@current_surfaces.b = external global i1 ; <i1*> [#uses=1]
declare double @sin(double) nounwind readonly
declare double @asin(double) nounwind readonly
define fastcc void @trace_line(i32 %line) nounwind {
entry:
%.b3 = load i1* @current_surfaces.b ; <i1> [#uses=1]
br i1 %.b3, label %bb.nph, label %return
bb.nph: ; preds = %entry
%0 = load double* null, align 8 ; <double> [#uses=1]
%1 = load double* null, align 8 ; <double> [#uses=2]
%2 = fcmp une double %0, 0.000000e+00 ; <i1> [#uses=1]
br i1 %2, label %bb9.i, label %bb13.i
bb9.i: ; preds = %bb.nph
%3 = tail call double @asin(double 0.000000e+00) nounwind readonly ; <double> [#uses=0]
%4 = fdiv double 1.000000e+00, %1 ; <double> [#uses=1]
%5 = mul double %4, 0.000000e+00 ; <double> [#uses=1]
%6 = tail call double @asin(double %5) nounwind readonly ; <double> [#uses=0]
unreachable
bb13.i: ; preds = %bb.nph
%7 = fdiv double 1.000000e+00, %1 ; <double> [#uses=1]
%8 = tail call double @sin(double 0.000000e+00) nounwind readonly ; <double> [#uses=1]
%9 = mul double %7, %8 ; <double> [#uses=1]
%10 = tail call double @asin(double %9) nounwind readonly ; <double> [#uses=0]
unreachable
return: ; preds = %entry
ret void
}