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fixup magic constant making code. tested by thousands of random divisions.... by 10000. ok, so random divisors would be good too, but this at least fixes some things

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21140 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Lenharth 2005-04-07 17:19:16 +00:00
parent 9bf59d7ed2
commit 320174f009
1 changed files with 10 additions and 10 deletions
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20
lib/Target/Alpha/AlphaISelPattern.cpp
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@ -413,7 +413,7 @@ static struct ms magic(int64_t d) {
ad = abs(d);
t = two63 + ((uint64_t)d >> 63);
anc = t - 1 - t%ad; // absolute value of nc
p = 31; // initialize p
p = 63; // initialize p
q1 = two63/anc; // initialize q1 = 2p/abs(nc)
r1 = two63 - q1*anc; // initialize r1 = rem(2p,abs(nc))
q2 = two63/ad; // initialize q2 = 2p/abs(d)
@ -450,11 +450,11 @@ static struct mu magicu(uint64_t d)
struct mu magu;
magu.a = 0; // initialize "add" indicator
nc = - 1 - (-d)%d;
p = 31; // initialize p
q1 = 0x8000000000000000ll/nc; // initialize q1 = 2p/nc
r1 = 0x8000000000000000ll - q1*nc; // initialize r1 = rem(2p,nc)
q2 = 0x7FFFFFFFFFFFFFFFll/d; // initialize q2 = (2p-1)/d
r2 = 0x7FFFFFFFFFFFFFFFll - q2*d; // initialize r2 = rem((2p-1),d)
p = 63; // initialize p
q1 = 0x8000000000000000ull/nc; // initialize q1 = 2p/nc
r1 = 0x8000000000000000ull - q1*nc; // initialize r1 = rem(2p,nc)
q2 = 0x7FFFFFFFFFFFFFFFull/d; // initialize q2 = (2p-1)/d
r2 = 0x7FFFFFFFFFFFFFFFull - q2*d; // initialize r2 = rem((2p-1),d)
do {
p = p + 1;
if (r1 >= nc - r1 ) {
@ -466,19 +466,19 @@ static struct mu magicu(uint64_t d)
r1 = 2*r1; // update r1
}
if (r2 + 1 >= d - r2) {
if (q2 >= 0x7FFFFFFFFFFFFFFFll) magu.a = 1;
if (q2 >= 0x7FFFFFFFFFFFFFFFull) magu.a = 1;
q2 = 2*q2 + 1; // update q2
r2 = 2*r2 + 1 - d; // update r2
}
else {
if (q2 >= 0x8000000000000000ll) magu.a = 1;
if (q2 >= 0x8000000000000000ull) magu.a = 1;
q2 = 2*q2; // update q2
r2 = 2*r2 + 1; // update r2
}
delta = d - 1 - r2;
} while (p < 64 && (q1 < delta || (q1 == delta && r1 == 0)));
magu.m = q2 + 1; // resulting magic number
magu.s = p - 32; // resulting shift
magu.s = p - 64; // resulting shift
return magu;
}
@ -487,7 +487,7 @@ static struct mu magicu(uint64_t d)
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDOperand ISel::BuildSDIVSequence(SDOperand N) {
int d = (int)cast<ConstantSDNode>(N.getOperand(1))->getSignExtended();
int64_t d = (int64_t)cast<ConstantSDNode>(N.getOperand(1))->getSignExtended();
ms magics = magic(d);
// Multiply the numerator (operand 0) by the magic value
SDOperand Q = ISelDAG->getNode(ISD::MULHS, MVT::i64, N.getOperand(0),