[llvm-commits] [llvm] r57185 - /llvm/trunk/lib/Support/APFloat.cpp
Dale Johannesen
dalej at apple.com
Mon Oct 6 11:22:29 PDT 2008
Author: johannes
Date: Mon Oct 6 13:22:29 2008
New Revision: 57185
URL: http://llvm.org/viewvc/llvm-project?rev=57185&view=rev
Log:
Mark shortening NaN conversions as Inexact. PR 2856.
Improve description of unsupported formats.
Modified:
llvm/trunk/lib/Support/APFloat.cpp
Modified: llvm/trunk/lib/Support/APFloat.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APFloat.cpp?rev=57185&r1=57184&r2=57185&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APFloat.cpp (original)
+++ llvm/trunk/lib/Support/APFloat.cpp Mon Oct 6 13:22:29 2008
@@ -1727,11 +1727,12 @@
APInt::tcShiftLeft(significandParts(), newPartCount, shift);
else if (shift < 0)
APInt::tcShiftRight(significandParts(), newPartCount, -shift);
+ // If the new size is shorter, we lost information.
+ fs = (shift < 0) ? opInexact : opOK;
// gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
// does not give you back the same bits. This is dubious, and we
// don't currently do it. You're really supposed to get
// an invalid operation signal at runtime, but nobody does that.
- fs = opOK;
} else {
semantics = &toSemantics;
fs = opOK;
@@ -2633,11 +2634,13 @@
return api.bitsToDouble();
}
-/// Integer bit is explicit in this format. Current Intel book does not
-/// define meaning of:
-/// exponent = all 1's, integer bit not set.
-/// exponent = 0, integer bit set. (formerly "psuedodenormals")
-/// exponent!=0 nor all 1's, integer bit not set. (formerly "unnormals")
+/// Integer bit is explicit in this format. Intel hardware (387 and later)
+/// does not support these bit patterns:
+/// exponent = all 1's, integer bit 0, significand 0 ("pseudoinfinity")
+/// exponent = all 1's, integer bit 0, significand nonzero ("pseudoNaN")
+/// exponent = 0, integer bit 1 ("pseudodenormal")
+/// exponent!=0 nor all 1's, integer bit 0 ("unnormal")
+/// At the moment, the first two are treated as NaNs, the second two as Normal.
void
APFloat::initFromF80LongDoubleAPInt(const APInt &api)
{
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