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Teach LowerBRCOND to recognize (xor (setcc x), 1). The xor inverts the condition. It's normally transformed by the dag combiner, unless the condition is set by a arithmetic op with overflow.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63505 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2009-02-02 08:07:36 +00:00
parent 585c51efbc
commit 67ad9db15b
2 changed files with 44 additions and 0 deletions
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21
lib/Target/X86/X86ISelLowering.cpp
View File

@ -5366,6 +5366,17 @@ static bool isAndOrOfSetCCs(SDValue Op, unsigned &Opc) {
Op.getOperand(1).hasOneUse());
}
static bool isXor1OfSetCC(SDValue Op) {
if (Op.getOpcode() != ISD::XOR)
return false;
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(Op.getOperand(1));
if (N1C && N1C->getAPIntValue() == 1) {
return Op.getOperand(0).getOpcode() == X86ISD::SETCC &&
Op.getOperand(0).hasOneUse();
}
return false;
}
SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) {
bool addTest = true;
SDValue Chain = Op.getOperand(0);
@ -5460,6 +5471,16 @@ SDValue X86TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) {
}
}
}
} else if (Cond.hasOneUse() && isXor1OfSetCC(Cond)) {
// Recognize for xorb (setcc), 1 patterns. The xor inverts the condition.
// It should be transformed during dag combiner except when the condition
// is set by a arithmetics with overflow node.
X86::CondCode CCode =
(X86::CondCode)Cond.getOperand(0).getConstantOperandVal(0);
CCode = X86::GetOppositeBranchCondition(CCode);
CC = DAG.getConstant(CCode, MVT::i8);
Cond = Cond.getOperand(0).getOperand(1);
addTest = false;
}
}

23
test/CodeGen/X86/smul-with-overflow-3.ll Normal file
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@ -0,0 +1,23 @@
; RUN: llvm-as < %s | llc -march=x86 | grep {jno} | count 1
@ok = internal constant [4 x i8] c"%d\0A\00"
@no = internal constant [4 x i8] c"no\0A\00"
define i1 @func1(i32 %v1, i32 %v2) nounwind {
entry:
%t = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %v1, i32 %v2)
%sum = extractvalue {i32, i1} %t, 0
%obit = extractvalue {i32, i1} %t, 1
br i1 %obit, label %overflow, label %normal
overflow:
%t2 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @no, i32 0, i32 0) ) nounwind
ret i1 false
normal:
%t1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @ok, i32 0, i32 0), i32 %sum ) nounwind
ret i1 true
}
declare i32 @printf(i8*, ...) nounwind
declare {i32, i1} @llvm.smul.with.overflow.i32(i32, i32)