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