[llvm-commits] CVS: llvm/lib/Target/X86/InstSelectSimple.cpp
Chris Lattner
lattner at cs.uiuc.edu
Mon Apr 5 22:16:02 PDT 2004
Changes in directory llvm/lib/Target/X86:
InstSelectSimple.cpp updated: 1.209 -> 1.210
---
Log message:
Emit more efficient 64-bit operations when the RHS is a constant, and one
of the words of the constant is zeros. For example:
Y = and long X, 1234
now generates:
Yl = and Xl, 1234
Yh = 0
instead of:
Yl = and Xl, 1234
Yh = and Xh, 0
---
Diffs of the changes: (+41 -5)
Index: llvm/lib/Target/X86/InstSelectSimple.cpp
diff -u llvm/lib/Target/X86/InstSelectSimple.cpp:1.209 llvm/lib/Target/X86/InstSelectSimple.cpp:1.210
--- llvm/lib/Target/X86/InstSelectSimple.cpp:1.209 Mon Apr 5 21:13:25 2004
+++ llvm/lib/Target/X86/InstSelectSimple.cpp Mon Apr 5 22:15:53 2004
@@ -1767,18 +1767,54 @@
};
unsigned Opcode = OpcodeTab[OperatorClass][Class];
+ unsigned Op1l = cast<ConstantInt>(Op1C)->getRawValue();
- uint64_t Op1v = cast<ConstantInt>(Op1C)->getRawValue();
- BuildMI(*MBB, IP, Opcode, 2, DestReg).addReg(Op0r).addImm(Op1v &0xFFFFFFFF);
+ if (Class != cLong) {
+ BuildMI(*MBB, IP, Opcode, 2, DestReg).addReg(Op0r).addImm(Op1l);
+ return;
+ } else {
+ // If this is a long value and the high or low bits have a special
+ // property, emit some special cases.
+ unsigned Op1h = cast<ConstantInt>(Op1C)->getRawValue() >> 32LL;
- if (Class == cLong) {
+ // If the constant is zero in the low 32-bits, just copy the low part
+ // across and apply the normal 32-bit operation to the high parts. There
+ // will be no carry or borrow into the top.
+ if (Op1l == 0) {
+ if (OperatorClass != 2) // All but and...
+ BuildMI(*MBB, IP, X86::MOV32rr, 1, DestReg).addReg(Op0r);
+ else
+ BuildMI(*MBB, IP, X86::MOV32ri, 1, DestReg).addImm(0);
+ BuildMI(*MBB, IP, OpcodeTab[OperatorClass][cLong], 2, DestReg+1)
+ .addReg(Op0r+1).addImm(Op1h);
+ return;
+ }
+
+ // If this is a logical operation and the top 32-bits are zero, just
+ // operate on the lower 32.
+ if (Op1h == 0 && OperatorClass > 1) {
+ BuildMI(*MBB, IP, OpcodeTab[OperatorClass][cLong], 2, DestReg)
+ .addReg(Op0r).addImm(Op1l);
+ if (OperatorClass != 2) // All but and
+ BuildMI(*MBB, IP, X86::MOV32rr, 1, DestReg+1).addReg(Op0r+1);
+ else
+ BuildMI(*MBB, IP, X86::MOV32ri, 1, DestReg+1).addImm(0);
+ return;
+ }
+
+ // TODO: We could handle lots of other special cases here, such as AND'ing
+ // with 0xFFFFFFFF00000000 -> noop, etc.
+
+ // Otherwise, code generate the full operation with a constant.
static const unsigned TopTab[] = {
X86::ADC32ri, X86::SBB32ri, X86::AND32ri, X86::OR32ri, X86::XOR32ri
};
+
+ BuildMI(*MBB, IP, Opcode, 2, DestReg).addReg(Op0r).addImm(Op1l);
BuildMI(*MBB, IP, TopTab[OperatorClass], 2, DestReg+1)
- .addReg(Op0r+1).addImm(uint64_t(Op1v) >> 32);
+ .addReg(Op0r+1).addImm(Op1h);
+ return;
}
- return;
}
// Finally, handle the general case now.
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