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Avoid putting a split past the end of the live range; always shrink wrap live interval in the barrier mbb.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58309 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-10-28 00:47:49 +00:00
parent e649778b55
commit f62ce370a4
3 changed files with 93 additions and 11 deletions
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31
lib/CodeGen/PreAllocSplitting.cpp
View File

@ -109,7 +109,7 @@ namespace {
SmallPtrSet<MachineInstr*, 4>&, unsigned&);
MachineBasicBlock::iterator
findRestorePoint(MachineBasicBlock*, MachineInstr*,
findRestorePoint(MachineBasicBlock*, MachineInstr*, unsigned,
SmallPtrSet<MachineInstr*, 4>&, unsigned&);
void RecordSplit(unsigned, unsigned, unsigned, int);
@ -203,12 +203,15 @@ PreAllocSplitting::findSpillPoint(MachineBasicBlock *MBB, MachineInstr *MI,
/// found.
MachineBasicBlock::iterator
PreAllocSplitting::findRestorePoint(MachineBasicBlock *MBB, MachineInstr *MI,
unsigned LastIdx,
SmallPtrSet<MachineInstr*, 4> &RefsInMBB,
unsigned &RestoreIndex) {
MachineBasicBlock::iterator Pt = MBB->end();
unsigned EndIdx = LIs->getMBBEndIdx(MBB);
// Go bottom up if RefsInMBB is empty.
if (RefsInMBB.empty()) {
// Go bottom up if RefsInMBB is empty and the end of the mbb isn't beyond
// the last index in the live range.
if (RefsInMBB.empty() && LastIdx >= EndIdx) {
MachineBasicBlock::iterator MII = MBB->end();
MachineBasicBlock::iterator EndPt = MI;
do {
@ -224,8 +227,12 @@ PreAllocSplitting::findRestorePoint(MachineBasicBlock *MBB, MachineInstr *MI,
} else {
MachineBasicBlock::iterator MII = MI;
MII = ++MII;
// FIXME: Limit the number of instructions to examine to reduce
// compile time?
while (MII != MBB->end()) {
unsigned Index = LIs->getInstructionIndex(MII);
if (Index > LastIdx)
break;
unsigned Gap = LIs->findGapBeforeInstr(Index);
if (Gap) {
Pt = MII;
@ -438,13 +445,15 @@ PreAllocSplitting::ShrinkWrapLiveInterval(VNInfo *ValNo, MachineBasicBlock *MBB,
// 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;
if (MBB != BarrierMBB) {
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);
@ -536,7 +545,7 @@ bool PreAllocSplitting::SplitRegLiveInterval(LiveInterval *LI) {
// Find a point to restore the value after the barrier.
unsigned RestoreIndex;
MachineBasicBlock::iterator RestorePt =
findRestorePoint(BarrierMBB, Barrier, RefsInMBB, RestoreIndex);
findRestorePoint(BarrierMBB, Barrier, LR->end, RefsInMBB, RestoreIndex);
if (RestorePt == BarrierMBB->end())
return false;

35
test/CodeGen/X86/pre-split8.ll Normal file
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@ -0,0 +1,35 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split -stats |& \
; RUN: grep {pre-alloc-split} | grep {Number of intervals split} | grep 1
@current_surfaces.b = external global i1 ; <i1*> [#uses=1]
declare double @asin(double) nounwind readonly
declare double @tan(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, label %return
bb: ; preds = %bb9.i, %entry
%.rle4 = phi double [ %7, %bb9.i ], [ 0.000000e+00, %entry ] ; <double> [#uses=1]
%0 = load double* null, align 8 ; <double> [#uses=3]
%1 = fcmp une double %0, 0.000000e+00 ; <i1> [#uses=1]
br i1 %1, label %bb9.i, label %bb13.i
bb9.i: ; preds = %bb
%2 = sub double %.rle4, %0 ; <double> [#uses=0]
%3 = tail call double @asin(double 0.000000e+00) nounwind readonly ; <double> [#uses=0]
%4 = mul double 0.000000e+00, %0 ; <double> [#uses=1]
%5 = tail call double @tan(double 0.000000e+00) nounwind readonly ; <double> [#uses=0]
%6 = mul double %4, 0.000000e+00 ; <double> [#uses=1]
%7 = add double %6, 0.000000e+00 ; <double> [#uses=1]
br i1 false, label %return, label %bb
bb13.i: ; preds = %bb
unreachable
return: ; preds = %bb9.i, %entry
ret void
}

38
test/CodeGen/X86/pre-split9.ll Normal file
View File

@ -0,0 +1,38 @@
; RUN: llvm-as < %s | llc -march=x86 -mattr=+sse2 -pre-alloc-split -stats |& \
; RUN: grep {pre-alloc-split} | grep {Number of intervals split} | grep 1
@current_surfaces.b = external global i1 ; <i1*> [#uses=1]
declare double @sin(double) nounwind readonly
declare double @asin(double) nounwind readonly
declare double @tan(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, label %return
bb: ; preds = %bb9.i, %entry
%.rle4 = phi double [ %8, %bb9.i ], [ 0.000000e+00, %entry ] ; <double> [#uses=1]
%0 = load double* null, align 8 ; <double> [#uses=3]
%1 = fcmp une double %0, 0.000000e+00 ; <i1> [#uses=1]
br i1 %1, label %bb9.i, label %bb13.i
bb9.i: ; preds = %bb
%2 = sub double %.rle4, %0 ; <double> [#uses=0]
%3 = tail call double @asin(double 0.000000e+00) nounwind readonly ; <double> [#uses=0]
%4 = tail call double @sin(double 0.000000e+00) nounwind readonly ; <double> [#uses=1]
%5 = mul double %4, %0 ; <double> [#uses=1]
%6 = tail call double @tan(double 0.000000e+00) nounwind readonly ; <double> [#uses=0]
%7 = mul double %5, 0.000000e+00 ; <double> [#uses=1]
%8 = add double %7, 0.000000e+00 ; <double> [#uses=1]
br i1 false, label %return, label %bb
bb13.i: ; preds = %bb
unreachable
return: ; preds = %bb9.i, %entry
ret void
}