[llvm-commits] [llvm] r70488 - in /llvm/trunk: include/llvm/ADT/APInt.h lib/CodeGen/SelectionDAG/TargetLowering.cpp lib/Support/APInt.cpp
Jay Foad
jay.foad at gmail.com
Thu Apr 30 03:15:41 PDT 2009
Author: foad
Date: Thu Apr 30 05:15:35 2009
New Revision: 70488
URL: http://llvm.org/viewvc/llvm-project?rev=70488&view=rev
Log:
Move helper functions for optimizing division by constant into the APInt
class.
Modified:
llvm/trunk/include/llvm/ADT/APInt.h
llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
llvm/trunk/lib/Support/APInt.cpp
Modified: llvm/trunk/include/llvm/ADT/APInt.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/APInt.h?rev=70488&r1=70487&r2=70488&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/APInt.h (original)
+++ llvm/trunk/include/llvm/ADT/APInt.h Thu Apr 30 05:15:35 2009
@@ -1258,6 +1258,18 @@
APInt multiplicativeInverse(const APInt& modulo) const;
/// @}
+ /// @name Support for division by constant
+ /// @{
+
+ /// Calculate the magic number for signed division by a constant.
+ struct ms;
+ ms magic() const;
+
+ /// Calculate the magic number for unsigned division by a constant.
+ struct mu;
+ mu magicu() const;
+
+ /// @}
/// @name Building-block Operations for APInt and APFloat
/// @{
@@ -1388,6 +1400,19 @@
/// @}
};
+/// Magic data for optimising signed division by a constant.
+struct APInt::ms {
+ APInt m; ///< magic number
+ unsigned s; ///< shift amount
+};
+
+/// Magic data for optimising unsigned division by a constant.
+struct APInt::mu {
+ APInt m; ///< magic number
+ bool a; ///< add indicator
+ unsigned s; ///< shift amount
+};
+
inline bool operator==(uint64_t V1, const APInt& V2) {
return V2 == V1;
}
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=70488&r1=70487&r2=70488&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Thu Apr 30 05:15:35 2009
@@ -2434,105 +2434,6 @@
return true;
}
-struct mu {
- APInt m; // magic number
- bool a; // add indicator
- unsigned s; // shift amount
-};
-
-/// magicu - calculate the magic numbers required to codegen an integer udiv as
-/// a sequence of multiply, add and shifts. Requires that the divisor not be 0.
-static mu magicu(const APInt& d) {
- unsigned p;
- APInt nc, delta, q1, r1, q2, r2;
- struct mu magu;
- magu.a = 0; // initialize "add" indicator
- APInt allOnes = APInt::getAllOnesValue(d.getBitWidth());
- APInt signedMin = APInt::getSignedMinValue(d.getBitWidth());
- APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth());
-
- nc = allOnes - (-d).urem(d);
- p = d.getBitWidth() - 1; // initialize p
- q1 = signedMin.udiv(nc); // initialize q1 = 2p/nc
- r1 = signedMin - q1*nc; // initialize r1 = rem(2p,nc)
- q2 = signedMax.udiv(d); // initialize q2 = (2p-1)/d
- r2 = signedMax - q2*d; // initialize r2 = rem((2p-1),d)
- do {
- p = p + 1;
- if (r1.uge(nc - r1)) {
- q1 = q1 + q1 + 1; // update q1
- r1 = r1 + r1 - nc; // update r1
- }
- else {
- q1 = q1+q1; // update q1
- r1 = r1+r1; // update r1
- }
- if ((r2 + 1).uge(d - r2)) {
- if (q2.uge(signedMax)) magu.a = 1;
- q2 = q2+q2 + 1; // update q2
- r2 = r2+r2 + 1 - d; // update r2
- }
- else {
- if (q2.uge(signedMin)) magu.a = 1;
- q2 = q2+q2; // update q2
- r2 = r2+r2 + 1; // update r2
- }
- delta = d - 1 - r2;
- } while (p < d.getBitWidth()*2 &&
- (q1.ult(delta) || (q1 == delta && r1 == 0)));
- magu.m = q2 + 1; // resulting magic number
- magu.s = p - d.getBitWidth(); // resulting shift
- return magu;
-}
-
-// Magic for divide replacement
-struct ms {
- APInt m; // magic number
- unsigned s; // shift amount
-};
-
-/// magic - calculate the magic numbers required to codegen an integer sdiv as
-/// a sequence of multiply and shifts. Requires that the divisor not be 0, 1,
-/// or -1.
-static ms magic(const APInt& d) {
- unsigned p;
- APInt ad, anc, delta, q1, r1, q2, r2, t;
- APInt allOnes = APInt::getAllOnesValue(d.getBitWidth());
- APInt signedMin = APInt::getSignedMinValue(d.getBitWidth());
- APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth());
- struct ms mag;
-
- ad = d.abs();
- t = signedMin + (d.lshr(d.getBitWidth() - 1));
- anc = t - 1 - t.urem(ad); // absolute value of nc
- p = d.getBitWidth() - 1; // initialize p
- q1 = signedMin.udiv(anc); // initialize q1 = 2p/abs(nc)
- r1 = signedMin - q1*anc; // initialize r1 = rem(2p,abs(nc))
- q2 = signedMin.udiv(ad); // initialize q2 = 2p/abs(d)
- r2 = signedMin - q2*ad; // initialize r2 = rem(2p,abs(d))
- do {
- p = p + 1;
- q1 = q1<<1; // update q1 = 2p/abs(nc)
- r1 = r1<<1; // update r1 = rem(2p/abs(nc))
- if (r1.uge(anc)) { // must be unsigned comparison
- q1 = q1 + 1;
- r1 = r1 - anc;
- }
- q2 = q2<<1; // update q2 = 2p/abs(d)
- r2 = r2<<1; // update r2 = rem(2p/abs(d))
- if (r2.uge(ad)) { // must be unsigned comparison
- q2 = q2 + 1;
- r2 = r2 - ad;
- }
- delta = ad - r2;
- } while (q1.ule(delta) || (q1 == delta && r1 == 0));
-
- mag.m = q2 + 1;
- if (d.isNegative()) mag.m = -mag.m; // resulting magic number
- mag.s = p - d.getBitWidth(); // resulting shift
- return mag;
-}
-
/// BuildSDIVSequence - Given an ISD::SDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
@@ -2548,7 +2449,7 @@
return SDValue();
APInt d = cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
- ms magics = magic(d);
+ APInt::ms magics = d.magic();
// Multiply the numerator (operand 0) by the magic value
// FIXME: We should support doing a MUL in a wider type
@@ -2607,7 +2508,7 @@
// FIXME: We should use a narrower constant when the upper
// bits are known to be zero.
ConstantSDNode *N1C = cast<ConstantSDNode>(N->getOperand(1));
- mu magics = magicu(N1C->getAPIntValue());
+ APInt::mu magics = N1C->getAPIntValue().magicu();
// Multiply the numerator (operand 0) by the magic value
// FIXME: We should support doing a MUL in a wider type
Modified: llvm/trunk/lib/Support/APInt.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APInt.cpp?rev=70488&r1=70487&r2=70488&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APInt.cpp (original)
+++ llvm/trunk/lib/Support/APInt.cpp Thu Apr 30 05:15:35 2009
@@ -1435,6 +1435,98 @@
return t[i].isNegative() ? t[i] + modulo : t[i];
}
+/// Calculate the magic numbers required to implement a signed integer division
+/// by a constant as a sequence of multiplies, adds and shifts. Requires that
+/// the divisor not be 0, 1, or -1. Taken from "Hacker's Delight", Henry S.
+/// Warren, Jr., chapter 10.
+APInt::ms APInt::magic() const {
+ const APInt& d = *this;
+ unsigned p;
+ APInt ad, anc, delta, q1, r1, q2, r2, t;
+ APInt allOnes = APInt::getAllOnesValue(d.getBitWidth());
+ APInt signedMin = APInt::getSignedMinValue(d.getBitWidth());
+ APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth());
+ struct ms mag;
+
+ ad = d.abs();
+ t = signedMin + (d.lshr(d.getBitWidth() - 1));
+ anc = t - 1 - t.urem(ad); // absolute value of nc
+ p = d.getBitWidth() - 1; // initialize p
+ q1 = signedMin.udiv(anc); // initialize q1 = 2p/abs(nc)
+ r1 = signedMin - q1*anc; // initialize r1 = rem(2p,abs(nc))
+ q2 = signedMin.udiv(ad); // initialize q2 = 2p/abs(d)
+ r2 = signedMin - q2*ad; // initialize r2 = rem(2p,abs(d))
+ do {
+ p = p + 1;
+ q1 = q1<<1; // update q1 = 2p/abs(nc)
+ r1 = r1<<1; // update r1 = rem(2p/abs(nc))
+ if (r1.uge(anc)) { // must be unsigned comparison
+ q1 = q1 + 1;
+ r1 = r1 - anc;
+ }
+ q2 = q2<<1; // update q2 = 2p/abs(d)
+ r2 = r2<<1; // update r2 = rem(2p/abs(d))
+ if (r2.uge(ad)) { // must be unsigned comparison
+ q2 = q2 + 1;
+ r2 = r2 - ad;
+ }
+ delta = ad - r2;
+ } while (q1.ule(delta) || (q1 == delta && r1 == 0));
+
+ mag.m = q2 + 1;
+ if (d.isNegative()) mag.m = -mag.m; // resulting magic number
+ mag.s = p - d.getBitWidth(); // resulting shift
+ return mag;
+}
+
+/// Calculate the magic numbers required to implement an unsigned integer
+/// division by a constant as a sequence of multiplies, adds and shifts.
+/// Requires that the divisor not be 0. Taken from "Hacker's Delight", Henry
+/// S. Warren, Jr., chapter 10.
+APInt::mu APInt::magicu() const {
+ const APInt& d = *this;
+ unsigned p;
+ APInt nc, delta, q1, r1, q2, r2;
+ struct mu magu;
+ magu.a = 0; // initialize "add" indicator
+ APInt allOnes = APInt::getAllOnesValue(d.getBitWidth());
+ APInt signedMin = APInt::getSignedMinValue(d.getBitWidth());
+ APInt signedMax = APInt::getSignedMaxValue(d.getBitWidth());
+
+ nc = allOnes - (-d).urem(d);
+ p = d.getBitWidth() - 1; // initialize p
+ q1 = signedMin.udiv(nc); // initialize q1 = 2p/nc
+ r1 = signedMin - q1*nc; // initialize r1 = rem(2p,nc)
+ q2 = signedMax.udiv(d); // initialize q2 = (2p-1)/d
+ r2 = signedMax - q2*d; // initialize r2 = rem((2p-1),d)
+ do {
+ p = p + 1;
+ if (r1.uge(nc - r1)) {
+ q1 = q1 + q1 + 1; // update q1
+ r1 = r1 + r1 - nc; // update r1
+ }
+ else {
+ q1 = q1+q1; // update q1
+ r1 = r1+r1; // update r1
+ }
+ if ((r2 + 1).uge(d - r2)) {
+ if (q2.uge(signedMax)) magu.a = 1;
+ q2 = q2+q2 + 1; // update q2
+ r2 = r2+r2 + 1 - d; // update r2
+ }
+ else {
+ if (q2.uge(signedMin)) magu.a = 1;
+ q2 = q2+q2; // update q2
+ r2 = r2+r2 + 1; // update r2
+ }
+ delta = d - 1 - r2;
+ } while (p < d.getBitWidth()*2 &&
+ (q1.ult(delta) || (q1 == delta && r1 == 0)));
+ magu.m = q2 + 1; // resulting magic number
+ magu.s = p - d.getBitWidth(); // resulting shift
+ return magu;
+}
+
/// Implementation of Knuth's Algorithm D (Division of nonnegative integers)
/// from "Art of Computer Programming, Volume 2", section 4.3.1, p. 272. The
/// variables here have the same names as in the algorithm. Comments explain
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