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Fixed a bug in the coalescer where intervals were occasionally merged despite a real interference. This fixes rdar://problem/7157961.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85338 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Lang Hames 2009-10-27 23:16:58 +00:00
parent a6a99b4e16
commit 1239c9656b
2 changed files with 22 additions and 2 deletions
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19
lib/CodeGen/SimpleRegisterCoalescing.cpp
View File

@ -1861,6 +1861,21 @@ bool SimpleRegisterCoalescing::RangeIsDefinedByCopyFromReg(LiveInterval &li,
return false;
}
/// ValueLiveAt - Return true if the LiveRange pointed to by the given
/// iterator, or any subsequent range with the same value number,
/// is live at the given point.
bool SimpleRegisterCoalescing::ValueLiveAt(LiveInterval::iterator LRItr,
LiveIndex defPoint) const {
for (const VNInfo *valno = LRItr->valno; LRItr->valno == valno; ++LRItr) {
if (LRItr->contains(defPoint))
return true;
}
return false;
}
/// SimpleJoin - Attempt to joint the specified interval into this one. The
/// caller of this method must guarantee that the RHS only contains a single
/// value number and that the RHS is not defined by a copy from this
@ -1907,7 +1922,7 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
if (!RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg))
return false; // Nope, bail out.
if (LHSIt->contains(RHSIt->valno->def))
if (ValueLiveAt(LHSIt, RHSIt->valno->def))
// Here is an interesting situation:
// BB1:
// vr1025 = copy vr1024
@ -1945,7 +1960,7 @@ bool SimpleRegisterCoalescing::SimpleJoin(LiveInterval &LHS, LiveInterval &RHS){
// Otherwise, if this is a copy from the RHS, mark it as being merged
// in.
if (RangeIsDefinedByCopyFromReg(LHS, LHSIt, RHS.reg)) {
if (LHSIt->contains(RHSIt->valno->def))
if (ValueLiveAt(LHSIt, RHSIt->valno->def))
// Here is an interesting situation:
// BB1:
// vr1025 = copy vr1024

5
lib/CodeGen/SimpleRegisterCoalescing.h
View File

@ -201,6 +201,11 @@ namespace llvm {
bool CanJoinInsertSubRegToPhysReg(unsigned DstReg, unsigned SrcReg,
unsigned SubIdx, unsigned &RealDstReg);
/// ValueLiveAt - Return true if the LiveRange pointed to by the given
/// iterator, or any subsequent range with the same value number,
/// is live at the given point.
bool ValueLiveAt(LiveInterval::iterator LRItr, LiveIndex defPoint) const;
/// RangeIsDefinedByCopyFromReg - Return true if the specified live range of
/// the specified live interval is defined by a copy from the specified
/// register.