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Folding into CSEL when there is ZEXT between SETCC and ADD

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Normally, patterns like (add x, (setcc cc ...)) will be folded into
(csel x, x+1, not cc). However, if there is a ZEXT after SETCC, they
won't be folded. This patch recognizes the ZEXT and allows the
generation of CSINC.

This patch fixes bug 19680.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208660 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Weiming Zhao 2014-05-13 00:40:58 +00:00
parent 5204fedd35
commit 0449d522a6
2 changed files with 22 additions and 3 deletions
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14
lib/Target/ARM64/ARM64ISelLowering.cpp
View File

@ -6600,8 +6600,16 @@ static bool isSetCC(SDValue Op, SetCCInfoAndKind &SetCCInfo) {
return TValue->isOne() && FValue->isNullValue();
}
// Returns true if Op is setcc or zext of setcc.
static bool isSetCCOrZExtSetCC(const SDValue& Op, SetCCInfoAndKind &Info) {
if (isSetCC(Op, Info))
return true;
return ((Op.getOpcode() == ISD::ZERO_EXTEND) &&
isSetCC(Op->getOperand(0), Info));
}
// The folding we want to perform is:
// (add x, (setcc cc ...) )
// (add x, [zext] (setcc cc ...) )
// -->
// (csel x, (add x, 1), !cc ...)
//
@ -6613,9 +6621,9 @@ static SDValue performSetccAddFolding(SDNode *Op, SelectionDAG &DAG) {
SetCCInfoAndKind InfoAndKind;
// If neither operand is a SET_CC, give up.
if (!isSetCC(LHS, InfoAndKind)) {
if (!isSetCCOrZExtSetCC(LHS, InfoAndKind)) {
std::swap(LHS, RHS);
if (!isSetCC(LHS, InfoAndKind))
if (!isSetCCOrZExtSetCC(LHS, InfoAndKind))
return SDValue();
}

11
test/CodeGen/ARM64/csel.ll
View File

@ -217,3 +217,14 @@ entry:
%. = select i1 %cmp, i64 1, i64 2
ret i64 %.
}
define i64 @foo19(i64 %a, i64 %b, i64 %c) {
entry:
; CHECK-LABEL: foo19:
; CHECK: cinc x0, x2
; CHECK-NOT: add
%cmp = icmp ult i64 %a, %b
%inc = zext i1 %cmp to i64
%inc.c = add i64 %inc, %c
ret i64 %inc.c
}