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X86 codegen tweak to use lea in another case:

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Suppose base == %eax and it has multiple uses, then instead of
  movl %eax, %ecx
  addl $8, %ecx
use
  leal 8(%eax), %ecx.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26323 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2006-02-23 00:13:58 +00:00
parent 4ba9cd53ba
commit 224ec39cab
1 changed files with 12 additions and 9 deletions
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21
lib/Target/X86/X86ISelDAGToDAG.cpp
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@@ -457,23 +457,19 @@ bool X86DAGToDAGISel::SelectLEAAddr(SDOperand N, SDOperand &Base,
SDOperand &Index, SDOperand &Disp) { SDOperand &Index, SDOperand &Disp) {
X86ISelAddressMode AM; X86ISelAddressMode AM;
if (!MatchAddress(N, AM)) { if (!MatchAddress(N, AM)) {
bool SelectBase = false;
bool SelectIndex = false; bool SelectIndex = false;
bool Check = false; bool Check = false;
if (AM.BaseType == X86ISelAddressMode::RegBase) { if (AM.BaseType == X86ISelAddressMode::RegBase) {
if (AM.Base.Reg.Val) { if (AM.Base.Reg.Val)
Check = true; Check = true;
SelectBase = true; else
} else {
AM.Base.Reg = CurDAG->getRegister(0, MVT::i32); AM.Base.Reg = CurDAG->getRegister(0, MVT::i32);
}
} }
if (AM.IndexReg.Val) { if (AM.IndexReg.Val)
SelectIndex = true; SelectIndex = true;
} else { else
AM.IndexReg = CurDAG->getRegister(0, MVT::i32); AM.IndexReg = CurDAG->getRegister(0, MVT::i32);
}
if (Check) { if (Check) {
unsigned Complexity = 0; unsigned Complexity = 0;
@@ -485,6 +481,13 @@ bool X86DAGToDAGISel::SelectLEAAddr(SDOperand N, SDOperand &Base,
Complexity++; Complexity++;
else if (AM.Disp > 1) else if (AM.Disp > 1)
Complexity++; Complexity++;
// Suppose base == %eax and it has multiple uses, then instead of
// movl %eax, %ecx
// addl $8, %ecx
// use
// leal 8(%eax), %ecx.
if (AM.Base.Reg.Val->use_size() > 1)
Complexity++;
if (Complexity <= 1) if (Complexity <= 1)
return false; return false;
} }