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Implement "AsCheapAsAMove" for some obviously cheap instructions: xor and the 

like.

llvm-svn: 51662
This commit is contained in:
Bill Wendling 2008-05-29 01:02:09 +00:00
parent f712664ec3
commit 7a1a8eb6e2
2 changed files with 50 additions and 42 deletions
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5
llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
View File

@ -330,10 +330,13 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
InstructionRearranged:
const TargetRegisterClass* rc = MF.getRegInfo().getRegClass(regA);
MachineInstr *Orig = MRI->getVRegDef(regB);
const TargetInstrDesc &OrigTID = Orig->getDesc();
bool SawStore = false;
if (EnableReMat && Orig && Orig->isSafeToMove(TII, SawStore) &&
TII->isTriviallyReMaterializable(Orig)) {
OrigTID.isAsCheapAsAMove() && !OrigTID.mayLoad() &&
!OrigTID.isSimpleLoad()) {
DEBUG(cerr << "2addr: REMATTING : " << *Orig << "\n");
TII->reMaterialize(*mbbi, mi, regA, Orig);
ReMattedInstrs.insert(Orig);
} else {

37
llvm/lib/Target/X86/X86InstrInfo.td
View File

@ -1309,23 +1309,24 @@ let isTwoAddress = 0 in {
def OR32mi8 : Ii8<0x83, MRM1m, (outs), (ins i32mem:$dst, i32i8imm:$src),
"or{l}\t{$src, $dst|$dst, $src}",
[(store (or (load addr:$dst), i32immSExt8:$src), addr:$dst)]>;
}
} // isTwoAddress = 0
let isCommutable = 1 in { // X = XOR Y, Z --> X = XOR Z, Y
def XOR8rr : I<0x30, MRMDestReg,
let isAsCheapAsAMove = 1,
isCommutable = 1 in { // X = XOR Y, Z --> X = XOR Z, Y
def XOR8rr : I<0x30, MRMDestReg,
(outs GR8 :$dst), (ins GR8 :$src1, GR8 :$src2),
"xor{b}\t{$src2, $dst|$dst, $src2}",
[(set GR8:$dst, (xor GR8:$src1, GR8:$src2))]>;
def XOR16rr : I<0x31, MRMDestReg,
def XOR16rr : I<0x31, MRMDestReg,
(outs GR16:$dst), (ins GR16:$src1, GR16:$src2),
"xor{w}\t{$src2, $dst|$dst, $src2}",
[(set GR16:$dst, (xor GR16:$src1, GR16:$src2))]>, OpSize;
def XOR32rr : I<0x31, MRMDestReg,
def XOR32rr : I<0x31, MRMDestReg,
(outs GR32:$dst), (ins GR32:$src1, GR32:$src2),
"xor{l}\t{$src2, $dst|$dst, $src2}",
[(set GR32:$dst, (xor GR32:$src1, GR32:$src2))]>;
}
} // isAsCheapAsAMove = 1, isCommutable = 1
def XOR8rm : I<0x32, MRMSrcMem ,
(outs GR8 :$dst), (ins GR8:$src1, i8mem :$src2),
@ -1334,33 +1335,37 @@ def XOR8rm : I<0x32, MRMSrcMem ,
def XOR16rm : I<0x33, MRMSrcMem ,
(outs GR16:$dst), (ins GR16:$src1, i16mem:$src2),
"xor{w}\t{$src2, $dst|$dst, $src2}",
[(set GR16:$dst, (xor GR16:$src1, (load addr:$src2)))]>, OpSize;
[(set GR16:$dst, (xor GR16:$src1, (load addr:$src2)))]>,
OpSize;
def XOR32rm : I<0x33, MRMSrcMem ,
(outs GR32:$dst), (ins GR32:$src1, i32mem:$src2),
"xor{l}\t{$src2, $dst|$dst, $src2}",
[(set GR32:$dst, (xor GR32:$src1, (load addr:$src2)))]>;
def XOR8ri : Ii8<0x80, MRM6r,
let isAsCheapAsAMove = 1 in {
def XOR8ri : Ii8<0x80, MRM6r,
(outs GR8:$dst), (ins GR8:$src1, i8imm:$src2),
"xor{b}\t{$src2, $dst|$dst, $src2}",
[(set GR8:$dst, (xor GR8:$src1, imm:$src2))]>;
def XOR16ri : Ii16<0x81, MRM6r,
def XOR16ri : Ii16<0x81, MRM6r,
(outs GR16:$dst), (ins GR16:$src1, i16imm:$src2),
"xor{w}\t{$src2, $dst|$dst, $src2}",
[(set GR16:$dst, (xor GR16:$src1, imm:$src2))]>, OpSize;
def XOR32ri : Ii32<0x81, MRM6r,
def XOR32ri : Ii32<0x81, MRM6r,
(outs GR32:$dst), (ins GR32:$src1, i32imm:$src2),
"xor{l}\t{$src2, $dst|$dst, $src2}",
[(set GR32:$dst, (xor GR32:$src1, imm:$src2))]>;
def XOR16ri8 : Ii8<0x83, MRM6r,
def XOR16ri8 : Ii8<0x83, MRM6r,
(outs GR16:$dst), (ins GR16:$src1, i16i8imm:$src2),
"xor{w}\t{$src2, $dst|$dst, $src2}",
[(set GR16:$dst, (xor GR16:$src1, i16immSExt8:$src2))]>,
OpSize;
def XOR32ri8 : Ii8<0x83, MRM6r,
def XOR32ri8 : Ii8<0x83, MRM6r,
(outs GR32:$dst), (ins GR32:$src1, i32i8imm:$src2),
"xor{l}\t{$src2, $dst|$dst, $src2}",
[(set GR32:$dst, (xor GR32:$src1, i32immSExt8:$src2))]>;
} // isAsCheapAsAMove = 1
let isTwoAddress = 0 in {
def XOR8mr : I<0x30, MRMDestMem,
(outs), (ins i8mem :$dst, GR8 :$src),
@ -1397,7 +1402,7 @@ let isTwoAddress = 0 in {
(outs), (ins i32mem:$dst, i32i8imm :$src),
"xor{l}\t{$src, $dst|$dst, $src}",
[(store (xor (load addr:$dst), i32immSExt8:$src), addr:$dst)]>;
}
} // isTwoAddress = 0
} // Defs = [EFLAGS]
// Shift instructions
@ -1412,7 +1417,7 @@ def SHL16rCL : I<0xD3, MRM4r, (outs GR16:$dst), (ins GR16:$src),
def SHL32rCL : I<0xD3, MRM4r, (outs GR32:$dst), (ins GR32:$src),
"shl{l}\t{%cl, $dst|$dst, %CL}",
[(set GR32:$dst, (shl GR32:$src, CL))]>;
}
} // Uses = [CL]
def SHL8ri : Ii8<0xC0, MRM4r, (outs GR8 :$dst), (ins GR8 :$src1, i8imm:$src2),
"shl{b}\t{$src2, $dst|$dst, $src2}",
@ -1426,7 +1431,7 @@ def SHL32ri : Ii8<0xC1, MRM4r, (outs GR32:$dst), (ins GR32:$src1, i8imm:$src2),
[(set GR32:$dst, (shl GR32:$src1, (i8 imm:$src2)))]>;
// NOTE: We don't use shifts of a register by one, because 'add reg,reg' is
// cheaper.
}
} // isConvertibleToThreeAddress = 1
let isTwoAddress = 0 in {
let Uses = [CL] in {
@ -2482,7 +2487,7 @@ let neverHasSideEffects = 1 in {
// Alias instructions that map movr0 to xor.
// FIXME: remove when we can teach regalloc that xor reg, reg is ok.
let Defs = [EFLAGS], isReMaterializable = 1 in {
let Defs = [EFLAGS], isReMaterializable = 1, isAsCheapAsAMove = 1 in {
def MOV8r0 : I<0x30, MRMInitReg, (outs GR8 :$dst), (ins),
"xor{b}\t$dst, $dst",
[(set GR8:$dst, 0)]>;