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Convert casts that will have no effect into move instructions.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15914 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2004-08-19 08:07:50 +00:00
parent 81d265d692
commit 1e67d4d7ba
1 changed files with 22 additions and 4 deletions
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26
lib/Target/PowerPC/PPC32ISelSimple.cpp
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@ -2580,7 +2580,7 @@ void ISel::visitCastInst(CastInst &CI) {
unsigned DestClass = getClassB(CI.getType());
// If this is a cast from a 32-bit integer to a Long type, and the only uses
// of the case are GEP instructions, then the cast does not need to be
// of the cast are GEP instructions, then the cast does not need to be
// generated explicitly, it will be folded into the GEP.
if (DestClass == cLong && SrcClass == cInt) {
bool AllUsesAreGEPs = true;
@ -2589,13 +2589,31 @@ void ISel::visitCastInst(CastInst &CI) {
AllUsesAreGEPs = false;
break;
}
// No need to codegen this cast if all users are getelementptr instrs...
if (AllUsesAreGEPs) return;
}
unsigned DestReg = getReg(CI);
MachineBasicBlock::iterator MI = BB->end();
// If this is a cast from an byte, short, or int to an integer type of equal
// or lesser width, and all uses of the cast are store instructions then dont
// emit them, as the store instruction will implicitly not store the zero or
// sign extended bytes.
if (SrcClass <= cInt && SrcClass >= DestClass) {
bool AllUsesAreStoresOrSetCC = true;
for (Value::use_iterator I = CI.use_begin(), E = CI.use_end(); I != E; ++I)
if (!isa<StoreInst>(*I) && !isa<SetCondInst>(*I)) {
AllUsesAreStoresOrSetCC = false;
break;
}
// Turn this cast directly into a move instruction, which the register
// allocator will deal with.
if (AllUsesAreStoresOrSetCC) {
unsigned SrcReg = getReg(Op, BB, MI);
BuildMI(*BB, MI, PPC::OR, 2, DestReg).addReg(SrcReg).addReg(SrcReg);
return;
}
}
emitCastOperation(BB, MI, Op, CI.getType(), DestReg);
}