RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2025-01-27 06:54:30 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Implement expansion in type legalization for add/sub with overflow. The

Browse Source 
expansion is the same as that used by LegalizeDAG.

The resulting code sucks in terms of performance/codesize on x86-32 for a
64-bit operation; I haven't looked into whether different expansions might be
better in general.

llvm-svn: 105378
This commit is contained in:
Eli Friedman 2010-06-03 03:49:50 +00:00
parent 37ee2be8cc
commit 60c8122bb0
3 changed files with 115 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

70
lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
View File

@ -990,6 +990,11 @@ void DAGTypeLegalizer::ExpandIntegerResult(SDNode *N, unsigned ResNo) {
case ISD::SHL:
case ISD::SRA:
case ISD::SRL: ExpandIntRes_Shift(N, Lo, Hi); break;
case ISD::SADDO:
case ISD::SSUBO: ExpandIntRes_SADDSUBO(N, Lo, Hi); break;
case ISD::UADDO:
case ISD::USUBO: ExpandIntRes_UADDSUBO(N, Lo, Hi); break;
}
// If Lo/Hi is null, the sub-method took care of registering results etc.
@ -1716,6 +1721,48 @@ void DAGTypeLegalizer::ExpandIntRes_MUL(SDNode *N,
SplitInteger(MakeLibCall(LC, VT, Ops, 2, true/*irrelevant*/, dl), Lo, Hi);
}
void DAGTypeLegalizer::ExpandIntRes_SADDSUBO(SDNode *Node,
SDValue &Lo, SDValue &Hi) {
SDValue LHS = Node->getOperand(0);
SDValue RHS = Node->getOperand(1);
DebugLoc dl = Node->getDebugLoc();
// Expand the result by simply replacing it with the equivalent
// non-overflow-checking operation.
SDValue Sum = DAG.getNode(Node->getOpcode() == ISD::SADDO ?
ISD::ADD : ISD::SUB, dl, LHS.getValueType(),
LHS, RHS);
SplitInteger(Sum, Lo, Hi);
// Compute the overflow.
//
// LHSSign -> LHS >= 0
// RHSSign -> RHS >= 0
// SumSign -> Sum >= 0
//
// Add:
// Overflow -> (LHSSign == RHSSign) && (LHSSign != SumSign)
// Sub:
// Overflow -> (LHSSign != RHSSign) && (LHSSign != SumSign)
//
EVT OType = Node->getValueType(1);
SDValue Zero = DAG.getConstant(0, LHS.getValueType());
SDValue LHSSign = DAG.getSetCC(dl, OType, LHS, Zero, ISD::SETGE);
SDValue RHSSign = DAG.getSetCC(dl, OType, RHS, Zero, ISD::SETGE);
SDValue SignsMatch = DAG.getSetCC(dl, OType, LHSSign, RHSSign,
Node->getOpcode() == ISD::SADDO ?
ISD::SETEQ : ISD::SETNE);
SDValue SumSign = DAG.getSetCC(dl, OType, Sum, Zero, ISD::SETGE);
SDValue SumSignNE = DAG.getSetCC(dl, OType, LHSSign, SumSign, ISD::SETNE);
SDValue Cmp = DAG.getNode(ISD::AND, dl, OType, SignsMatch, SumSignNE);
// Use the calculated overflow everywhere.
ReplaceValueWith(SDValue(Node, 1), Cmp);
}
void DAGTypeLegalizer::ExpandIntRes_SDIV(SDNode *N,
SDValue &Lo, SDValue &Hi) {
EVT VT = N->getValueType(0);
@ -1912,6 +1959,29 @@ void DAGTypeLegalizer::ExpandIntRes_TRUNCATE(SDNode *N,
Hi = DAG.getNode(ISD::TRUNCATE, dl, NVT, Hi);
}
void DAGTypeLegalizer::ExpandIntRes_UADDSUBO(SDNode *N,
SDValue &Lo, SDValue &Hi) {
SDValue LHS = N->getOperand(0);
SDValue RHS = N->getOperand(1);
DebugLoc dl = N->getDebugLoc();
// Expand the result by simply replacing it with the equivalent
// non-overflow-checking operation.
SDValue Sum = DAG.getNode(N->getOpcode() == ISD::UADDO ?
ISD::ADD : ISD::SUB, dl, LHS.getValueType(),
LHS, RHS);
SplitInteger(Sum, Lo, Hi);
// Calculate the overflow: addition overflows iff a + b < a, and subtraction
// overflows iff a - b > a.
SDValue Ofl = DAG.getSetCC(dl, N->getValueType(1), Sum, LHS,
N->getOpcode () == ISD::UADDO ?
ISD::SETULT : ISD::SETUGT);
// Use the calculated overflow everywhere.
ReplaceValueWith(SDValue(N, 1), Ofl);
}
void DAGTypeLegalizer::ExpandIntRes_UDIV(SDNode *N,
SDValue &Lo, SDValue &Hi) {
EVT VT = N->getValueType(0);

3
lib/CodeGen/SelectionDAG/LegalizeTypes.h
View File

@ -345,6 +345,9 @@ private:
void ExpandIntRes_UREM (SDNode *N, SDValue &Lo, SDValue &Hi);
void ExpandIntRes_Shift (SDNode *N, SDValue &Lo, SDValue &Hi);
void ExpandIntRes_SADDSUBO (SDNode *N, SDValue &Lo, SDValue &Hi);
void ExpandIntRes_UADDSUBO (SDNode *N, SDValue &Lo, SDValue &Hi);
void ExpandShiftByConstant(SDNode *N, unsigned Amt,
SDValue &Lo, SDValue &Hi);
bool ExpandShiftWithKnownAmountBit(SDNode *N, SDValue &Lo, SDValue &Hi);

42
test/CodeGen/Generic/add-with-overflow-128.ll Normal file
View File

@ -0,0 +1,42 @@
; RUN: llc < %s
@ok = internal constant [4 x i8] c"%d\0A\00"
@no = internal constant [4 x i8] c"no\0A\00"
define i1 @func1(i128 signext %v1, i128 signext %v2) nounwind {
entry:
%t = call {i128, i1} @llvm.sadd.with.overflow.i128(i128 %v1, i128 %v2)
%sum = extractvalue {i128, i1} %t, 0
%sum32 = trunc i128 %sum to i32
%obit = extractvalue {i128, i1} %t, 1
br i1 %obit, label %overflow, label %normal
normal:
%t1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @ok, i32 0, i32 0), i32 %sum32 ) nounwind
ret i1 true
overflow:
%t2 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @no, i32 0, i32 0) ) nounwind
ret i1 false
}
define i1 @func2(i128 zeroext %v1, i128 zeroext %v2) nounwind {
entry:
%t = call {i128, i1} @llvm.uadd.with.overflow.i128(i128 %v1, i128 %v2)
%sum = extractvalue {i128, i1} %t, 0
%sum32 = trunc i128 %sum to i32
%obit = extractvalue {i128, i1} %t, 1
br i1 %obit, label %carry, label %normal
normal:
%t1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @ok, i32 0, i32 0), i32 %sum32 ) nounwind
ret i1 true
carry:
%t2 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @no, i32 0, i32 0) ) nounwind
ret i1 false
}
declare i32 @printf(i8*, ...) nounwind
declare {i128, i1} @llvm.sadd.with.overflow.i128(i128, i128)
declare {i128, i1} @llvm.uadd.with.overflow.i128(i128, i128)