[mips] Improve genConstMult() to work with arbitrary precision
APInt is now used instead of uint64_t in function genConstMult() allowing
multiplication optimizations with constants of arbitrary length.
Patch by Milos Stojanovic.
Differential Revision: https://reviews.llvm.org/D38130
llvm-svn: 318296
diff --git a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
index 4dd9f7f..c60e4a1 100644
--- a/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
+++ b/llvm/lib/Target/Mips/MipsSEISelLowering.cpp
@@ -701,11 +701,8 @@
return SDValue();
}
-static SDValue genConstMult(SDValue X, uint64_t C, const SDLoc &DL, EVT VT,
+static SDValue genConstMult(SDValue X, APInt C, const SDLoc &DL, EVT VT,
EVT ShiftTy, SelectionDAG &DAG) {
- // Clear the upper (64 - VT.sizeInBits) bits.
- C &= ((uint64_t)-1) >> (64 - VT.getSizeInBits());
-
// Return 0.
if (C == 0)
return DAG.getConstant(0, DL, VT);
@@ -715,18 +712,19 @@
return X;
// If c is power of 2, return (shl x, log2(c)).
- if (isPowerOf2_64(C))
+ if (C.isPowerOf2())
return DAG.getNode(ISD::SHL, DL, VT, X,
- DAG.getConstant(Log2_64(C), DL, ShiftTy));
+ DAG.getConstant(C.logBase2(), DL, ShiftTy));
- unsigned Log2Ceil = Log2_64_Ceil(C);
- uint64_t Floor = 1LL << Log2_64(C);
- uint64_t Ceil = Log2Ceil == 64 ? 0LL : 1LL << Log2Ceil;
+ unsigned BitWidth = C.getBitWidth();
+ APInt Floor = APInt(BitWidth, 1) << C.logBase2();
+ APInt Ceil = C.isNegative() ? APInt(BitWidth, 0) :
+ APInt(BitWidth, 1) << C.ceilLogBase2();
// If |c - floor_c| <= |c - ceil_c|,
// where floor_c = pow(2, floor(log2(c))) and ceil_c = pow(2, ceil(log2(c))),
// return (add constMult(x, floor_c), constMult(x, c - floor_c)).
- if (C - Floor <= Ceil - C) {
+ if ((C - Floor).ule(Ceil - C)) {
SDValue Op0 = genConstMult(X, Floor, DL, VT, ShiftTy, DAG);
SDValue Op1 = genConstMult(X, C - Floor, DL, VT, ShiftTy, DAG);
return DAG.getNode(ISD::ADD, DL, VT, Op0, Op1);
@@ -746,7 +744,7 @@
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(N->getOperand(1)))
if (!VT.isVector())
- return genConstMult(N->getOperand(0), C->getZExtValue(), SDLoc(N), VT,
+ return genConstMult(N->getOperand(0), C->getAPIntValue(), SDLoc(N), VT,
TL->getScalarShiftAmountTy(DAG.getDataLayout(), VT),
DAG);