Fix a minor bug in previous checking
Enable folding of long seteq/setne comparisons into branches and select instructions
Implement unfolded long relational comparisons against a constants a bit more efficiently
Folding comparisons changes code that looks like this:
mov %EAX, DWORD PTR [%ESP + 4]
mov %EDX, DWORD PTR [%ESP + 8]
mov %ECX, %EAX
or %ECX, %EDX
sete %CL
test %CL, %CL
je .LBB2 # PC rel: F
into code that looks like this:
mov %EAX, DWORD PTR [%ESP + 4]
mov %EDX, DWORD PTR [%ESP + 8]
mov %ECX, %EAX
or %ECX, %EDX
jne .LBB2 # PC rel: F
This speeds up 186.crafty by 6% with llc-ls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12702 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/InstSelectSimple.cpp b/lib/Target/X86/InstSelectSimple.cpp
index 527bd1b..05d2d88 100644
--- a/lib/Target/X86/InstSelectSimple.cpp
+++ b/lib/Target/X86/InstSelectSimple.cpp
@@ -756,7 +756,9 @@
Instruction *User = cast<Instruction>(SCI->use_back());
if ((isa<BranchInst>(User) || isa<SelectInst>(User)) &&
SCI->getParent() == User->getParent() &&
- getClassB(SCI->getOperand(0)->getType()) != cLong)
+ (getClassB(SCI->getOperand(0)->getType()) != cLong ||
+ SCI->getOpcode() == Instruction::SetEQ ||
+ SCI->getOpcode() == Instruction::SetNE))
return SCI;
}
return 0;
@@ -846,11 +848,36 @@
unsigned HiTmp = Op0r+1;
if (HiCst != 0) {
HiTmp = makeAnotherReg(Type::IntTy);
- BuildMI(*MBB, IP, X86::XOR32rr, 2,HiTmp).addReg(Op0r+1).addImm(HiCst);
+ BuildMI(*MBB, IP, X86::XOR32ri, 2,HiTmp).addReg(Op0r+1).addImm(HiCst);
}
unsigned FinalTmp = makeAnotherReg(Type::IntTy);
BuildMI(*MBB, IP, X86::OR32rr, 2, FinalTmp).addReg(LoTmp).addReg(HiTmp);
return OpNum;
+ } else {
+ // Emit a sequence of code which compares the high and low parts once
+ // each, then uses a conditional move to handle the overflow case. For
+ // example, a setlt for long would generate code like this:
+ //
+ // AL = lo(op1) < lo(op2) // Signedness depends on operands
+ // BL = hi(op1) < hi(op2) // Always unsigned comparison
+ // dest = hi(op1) == hi(op2) ? AL : BL;
+ //
+
+ // FIXME: This would be much better if we had hierarchical register
+ // classes! Until then, hardcode registers so that we can deal with
+ // their aliases (because we don't have conditional byte moves).
+ //
+ BuildMI(*MBB, IP, X86::CMP32ri, 2).addReg(Op0r).addImm(LowCst);
+ BuildMI(*MBB, IP, SetCCOpcodeTab[0][OpNum], 0, X86::AL);
+ BuildMI(*MBB, IP, X86::CMP32ri, 2).addReg(Op0r+1).addImm(HiCst);
+ BuildMI(*MBB, IP, SetCCOpcodeTab[CompTy->isSigned()][OpNum], 0,X86::BL);
+ BuildMI(*MBB, IP, X86::IMPLICIT_DEF, 0, X86::BH);
+ BuildMI(*MBB, IP, X86::IMPLICIT_DEF, 0, X86::AH);
+ BuildMI(*MBB, IP, X86::CMOVE16rr, 2, X86::BX).addReg(X86::BX)
+ .addReg(X86::AX);
+ // NOTE: visitSetCondInst knows that the value is dumped into the BL
+ // register at this point for long values...
+ return OpNum;
}
}
}