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Teach MatchScaledValue to handle Scales by 1 with MatchAddr (which

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can recursively match things) and scales by 0 by ignoring them.
This triggers once in 403.gcc, saving 1 (!!!!) instruction in the 
whole huge app.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60013 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-11-25 07:25:26 +00:00
parent 88a5c832ac
commit 3b48501adc
1 changed files with 15 additions and 5 deletions
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20
lib/Transforms/Scalar/CodeGenPrepare.cpp
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@ -557,7 +557,7 @@ public:
return Result;
}
private:
bool MatchScaledValue(Value *ScaleReg, int64_t Scale);
bool MatchScaledValue(Value *ScaleReg, int64_t Scale, unsigned Depth);
bool MatchAddr(Value *V, unsigned Depth);
bool MatchOperationAddr(User *Operation, unsigned Opcode, unsigned Depth);
};
@ -566,7 +566,17 @@ private:
/// MatchScaledValue - Try adding ScaleReg*Scale to the current addressing mode.
/// Return true and update AddrMode if this addr mode is legal for the target,
/// false if not.
bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale) {
bool AddressingModeMatcher::MatchScaledValue(Value *ScaleReg, int64_t Scale,
unsigned Depth) {
// If Scale is 1, then this is the same as adding ScaleReg to the addressing
// mode. Just process that directly.
if (Scale == 1)
return MatchAddr(ScaleReg, Depth);
// If the scale is 0, it takes nothing to add this.
if (Scale == 0)
return true;
// If we already have a scale of this value, we can add to it, otherwise, we
// need an available scale field.
if (AddrMode.Scale != 0 && AddrMode.ScaledReg != ScaleReg)
@ -663,7 +673,7 @@ bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
if (Opcode == Instruction::Shl)
Scale = 1 << Scale;
return MatchScaledValue(AddrInst->getOperand(0), Scale);
return MatchScaledValue(AddrInst->getOperand(0), Scale, Depth);
}
case Instruction::GetElementPtr: {
// Scan the GEP. We check it if it contains constant offsets and at most
@ -728,8 +738,8 @@ bool AddressingModeMatcher::MatchOperationAddr(User *AddrInst, unsigned Opcode,
// See if the scale and offset amount is valid for this target.
AddrMode.BaseOffs += ConstantOffset;
// FIXME: If VariableScale = 1, just call MatchAddr recursively?
if (!MatchScaledValue(AddrInst->getOperand(VariableOperand),VariableScale)){
if (!MatchScaledValue(AddrInst->getOperand(VariableOperand), VariableScale,
Depth)) {
AddrMode = BackupAddrMode;
return false;
}