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Add a MinNumRegs argument to MRI::constrainRegClass().

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The function will refuse to use a register class with fewer registers
than MinNumRegs.  This can be used by clients to avoid accidentally
increase register pressure too much.

The default value of MinNumRegs=0 doesn't affect how constrainRegClass()
works.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140339 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-09-22 21:39:31 +00:00
parent 17470bee5f
commit 91fb536a34
2 changed files with 11 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
lib/CodeGen/MachineRegisterInfo.cpp
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@@ -49,15 +49,17 @@ MachineRegisterInfo::setRegClass(unsigned Reg, const TargetRegisterClass *RC) {
const TargetRegisterClass *
MachineRegisterInfo::constrainRegClass(unsigned Reg,
const TargetRegisterClass *RC) {
const TargetRegisterClass *RC,
unsigned MinNumRegs) {
const TargetRegisterClass *OldRC = getRegClass(Reg);
if (OldRC == RC)
return RC;
const TargetRegisterClass *NewRC = getCommonSubClass(OldRC, RC);
if (!NewRC)
if (!NewRC || NewRC == OldRC)
return NewRC;
if (NewRC->getNumRegs() < MinNumRegs)
return 0;
if (NewRC != OldRC)
setRegClass(Reg, NewRC);
setRegClass(Reg, NewRC);
return NewRC;
}