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Substantially improve the code generated by non-folded setcc instructions. 

In particular, instead of compiling this:

bool %test(int %A, int %B) {
  %C = setlt int %A, %B
  ret bool %C
}

to this:

test:
        save %sp, -96, %sp
        subcc %i0, %i1, %g0
        bl .LBBtest_1   !
        nop
        ba .LBBtest_2   !
        nop
.LBBtest_1:     !
        or %g0, 1, %i0
        ba .LBBtest_3   !
        nop
.LBBtest_2:     !
        or %g0, 0, %i0
        ba .LBBtest_3   !
        nop
.LBBtest_3:     !
        restore %g0, %g0, %g0
        retl
        nop

We now compile it to this:

test:
        save %sp, -96, %sp
        subcc %i0, %i1, %g0
        or %g0, 1, %i0
        bl .LBBtest_2   !
        nop
.LBBtest_1:     !
        or %g0, %g0, %i0
.LBBtest_2:     !
        restore %g0, %g0, %g0
        retl
        nop

llvm-svn: 19213
This commit is contained in:
Chris Lattner 2005-01-01 16:06:57 +00:00
parent 3215bb6049
commit 78394258ae
1 changed files with 19 additions and 32 deletions
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51
llvm/lib/Target/SparcV8/SparcV8ISelSimple.cpp
View File

@ -251,7 +251,6 @@ void V8ISel::copyConstantToRegister(MachineBasicBlock *MBB,
}
if (C->getType()->isIntegral ()) {
uint64_t Val;
unsigned Class = getClassB (C->getType ());
if (Class == cLong) {
unsigned TmpReg = makeAnotherReg (Type::IntTy);
@ -267,12 +266,13 @@ void V8ISel::copyConstantToRegister(MachineBasicBlock *MBB,
}
assert(Class <= cInt && "Type not handled yet!");
unsigned Val;
if (C->getType() == Type::BoolTy) {
Val = (C == ConstantBool::True);
} else {
ConstantIntegral *CI = cast<ConstantIntegral> (C);
Val = CI->getRawValue ();
Val = CI->getRawValue();
}
if (C->getType()->isSigned()) {
switch (Class) {
@ -289,7 +289,7 @@ void V8ISel::copyConstantToRegister(MachineBasicBlock *MBB,
}
if (Val == 0) {
BuildMI (*MBB, IP, V8::ORrr, 2, R).addReg (V8::G0).addReg(V8::G0);
} else if (((int64_t)Val >= -4096) && ((int64_t)Val <= 4095)) {
} else if ((int)Val >= -4096 && (int)Val <= 4095) {
BuildMI (*MBB, IP, V8::ORri, 2, R).addReg (V8::G0).addSImm(Val);
} else {
unsigned TmpReg = makeAnotherReg (C->getType ());
@ -1639,55 +1639,42 @@ void V8ISel::visitSetCondInst(SetCondInst &I) {
// thisMBB:
// ...
// subcc %reg0, %reg1, %g0
// bCC copy1MBB
// ba copy0MBB
// TrueVal = or G0, 1
// bCC sinkMBB
unsigned TrueValue = makeAnotherReg (I.getType ());
BuildMI (BB, V8::ORri, 2, TrueValue).addReg (V8::G0).addZImm (1);
// FIXME: we wouldn't need copy0MBB (we could fold it into thisMBB)
// if we could insert other, non-terminator instructions after the
// bCC. But MBB->getFirstTerminator() can't understand this.
MachineBasicBlock *copy1MBB = new MachineBasicBlock (LLVM_BB);
F->getBasicBlockList ().push_back (copy1MBB);
BuildMI (BB, Opcode, 1).addMBB (copy1MBB);
MachineBasicBlock *copy0MBB = new MachineBasicBlock (LLVM_BB);
F->getBasicBlockList ().push_back (copy0MBB);
BuildMI (BB, V8::BA, 1).addMBB (copy0MBB);
MachineBasicBlock *sinkMBB = new MachineBasicBlock (LLVM_BB);
BuildMI (BB, Opcode, 1).addMBB (sinkMBB);
// Update machine-CFG edges
BB->addSuccessor (copy1MBB);
BB->addSuccessor (sinkMBB);
BB->addSuccessor (copy0MBB);
// copy0MBB:
// %FalseValue = or %G0, 0
// ba sinkMBB
// # fall through
BB = copy0MBB;
F->getBasicBlockList ().push_back (BB);
unsigned FalseValue = makeAnotherReg (I.getType ());
BuildMI (BB, V8::ORri, 2, FalseValue).addReg (V8::G0).addZImm (0);
MachineBasicBlock *sinkMBB = new MachineBasicBlock (LLVM_BB);
F->getBasicBlockList ().push_back (sinkMBB);
BuildMI (BB, V8::BA, 1).addMBB (sinkMBB);
BuildMI (BB, V8::ORrr, 2, FalseValue).addReg (V8::G0).addReg (V8::G0);
// Update machine-CFG edges
BB->addSuccessor (sinkMBB);
DEBUG (std::cerr << "thisMBB is at " << (void*)thisMBB << "\n");
DEBUG (std::cerr << "copy1MBB is at " << (void*)copy1MBB << "\n");
DEBUG (std::cerr << "copy0MBB is at " << (void*)copy0MBB << "\n");
DEBUG (std::cerr << "sinkMBB is at " << (void*)sinkMBB << "\n");
// copy1MBB:
// %TrueValue = or %G0, 1
// ba sinkMBB
BB = copy1MBB;
unsigned TrueValue = makeAnotherReg (I.getType ());
BuildMI (BB, V8::ORri, 2, TrueValue).addReg (V8::G0).addZImm (1);
BuildMI (BB, V8::BA, 1).addMBB (sinkMBB);
// Update machine-CFG edges
BB->addSuccessor (sinkMBB);
// sinkMBB:
// %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, copy1MBB ]
// %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = sinkMBB;
F->getBasicBlockList ().push_back (BB);
BuildMI (BB, V8::PHI, 4, DestReg).addReg (FalseValue)
.addMBB (copy0MBB).addReg (TrueValue).addMBB (copy1MBB);
.addMBB (copy0MBB).addReg (TrueValue).addMBB (thisMBB);
}
void V8ISel::visitAllocaInst(AllocaInst &I) {