Reapply r216913, a fix for PR20832 by Andrea Di Biagio. The commit was reverted
because of buildbot failures, and credit goes to Ulrich Weigand for isolating
the underlying issue (which can be confirmed by Valgrind, which does helpfully
light up like the fourth of July). Uli explained the problem with the original
patch as:
It seems the problem is calling multiplySignificand with an addend of category
fcZero; that is not expected by this routine. Note that for fcZero, the
significand parts are simply uninitialized, but the code in (or rather, called
from) multiplySignificand will unconditionally access them -- in effect using
uninitialized contents.
This version avoids using a category == fcZero addend within
multiplySignificand, which avoids this problem (the Valgrind output is also now
clean).
Original commit message:
[APFloat] Fixed a bug in method 'fusedMultiplyAdd'.
When folding a fused multiply-add builtin call, make sure that we propagate the
correct result in the case where the addend is zero, and the two other operands
are finite non-zero.
Example:
define double @test() {
%1 = call double @llvm.fma.f64(double 7.0, double 8.0, double 0.0)
ret double %1
}
Before this patch, the instruction simplifier wrongly folded the builtin call
in function @test to constant 'double 7.0'.
With this patch, method 'fusedMultiplyAdd' correctly evaluates the multiply and
propagates the expected result (i.e. 56.0).
Added test fold-builtin-fma.ll with the reproducible from PR20832 plus extra
test cases to verify the behavior of method 'fusedMultiplyAdd' in the presence
of NaN/Inf operands.
This fixes PR20832.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219708 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts revision 216913; the new test added at revision 216913
caused regression failures on a couple of buildbots.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216914 91177308-0d34-0410-b5e6-96231b3b80d8
When folding a fused multiply-add builtin call, make sure that we propagate the
correct result in the case where the addend is zero, and the two other operands
are finite non-zero.
Example:
define double @test() {
%1 = call double @llvm.fma.f64(double 7.0, double 8.0, double 0.0)
ret double %1
}
Before this patch, the instruction simplifier wrongly folded the builtin call
in function @test to constant 'double 7.0'.
With this patch, method 'fusedMultiplyAdd' correctly evaluates the multiply and
propagates the expected result (i.e. 56.0).
Added test fold-builtin-fma.ll with the reproducible from PR20832 plus extra
test cases to verify the behavior of method 'fusedMultiplyAdd' in the presence
of NaN/Inf operands.
This fixes PR20832.
Differential Revision: http://reviews.llvm.org/D5152
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216913 91177308-0d34-0410-b5e6-96231b3b80d8
Because we don't have a separate negate( ) function, 0 - NaN does double-duty as the IEEE-754 negate( ) operation, which (unlike most FP ops) *does* attach semantic meaning to the signbit of NaN.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210428 91177308-0d34-0410-b5e6-96231b3b80d8
Sweep the codebase for common typos. Includes some changes to visible function
names that were misspelt.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200018 91177308-0d34-0410-b5e6-96231b3b80d8
This patch tries to avoid unrelated changes other than fixing a few
hyphen-related ambiguities and contractions in nearby lines.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196471 91177308-0d34-0410-b5e6-96231b3b80d8
This is a re-commit of r189442; I'll follow up with clang changes.
The previous default was almost, but not quite enough digits to
represent a floating-point value in a manner which preserves the
representation when it's read back in. The larger default is much
less confusing.
I spent some time looking into printing exactly the right number of
digits if a precision isn't specified, but it's kind of complicated,
and I'm not really sure I understand what APFloat::toString is supposed
to output for FormatPrecision != 0 (or maybe the current API specification
is just silly, not sure which). I have a WIP patch if anyone is interested.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189624 91177308-0d34-0410-b5e6-96231b3b80d8
The previous default was almost, but not quite enough digits to
represent a floating-point value in a manner which preserves the
representation when it's read back in. The larger default is much
less confusing.
I spent some time looking into printing exactly the right number of
digits if a precision isn't specified, but it's kind of complicated,
and I'm not really sure I understand what APFloat::toString is supposed
to output for FormatPrecision != 0 (or maybe the current API specification
is just silly, not sure which). I have a WIP patch if anyone is interested.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189442 91177308-0d34-0410-b5e6-96231b3b80d8
IEEE-754R 1.4 Exclusions states that IEEE-754R does not specify the
interpretation of the sign of NaNs. In order to remove an irrelevant
variable that most floating point implementations do not use,
standardize add, sub, mul, div, mod so that operating anything with
NaN always yields a positive NaN.
In a later commit I am going to update the APIs for creating NaNs so
that one can not even create a negative NaN.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187314 91177308-0d34-0410-b5e6-96231b3b80d8
Zeroing the significand of a floating point number does not necessarily cause a
floating point number to become finite non zero. For instance, if one has a NaN,
zeroing the significand will cause it to become +/- infinity.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187313 91177308-0d34-0410-b5e6-96231b3b80d8
There were a couple of different loops that were not handling
'.' correctly in APFloat::convertFromHexadecimalString; these mistakes
could lead to assertion failures and incorrect rounding for overlong
hex float literals.
Fixes PR16643.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186539 91177308-0d34-0410-b5e6-96231b3b80d8
When truncating to a format with fewer mantissa bits, APFloat::convert
will perform a right shift of the mantissa by the difference of the
precision of the two formats. Usually, this will result in just the
mantissa bits needed for the target format.
One special situation is if the input number is denormal. In this case,
the right shift may discard significant bits. This is usually not a
problem, since truncating a denormal usually results in zero (underflow)
after normalization anyway, since the result format's exponent range is
usually smaller than the target format's.
However, there is one case where the latter property does not hold:
when truncating from ppc_fp128 to double. In particular, truncating
a ppc_fp128 whose first double of the pair is denormal should result
in just that first double, not zero. The current code however
performs an excessive right shift, resulting in lost result bits.
This is then caught in the APFloat::normalize call performed by
APFloat::convert and causes an assertion failure.
This patch checks for the scenario of truncating a denormal, and
attempts to (possibly partially) replace the initial mantissa
right shift by decrementing the exponent, if doing so will still
result in a valid *target format* exponent.
Index: test/CodeGen/PowerPC/pr16573.ll
===================================================================
--- test/CodeGen/PowerPC/pr16573.ll (revision 0)
+++ test/CodeGen/PowerPC/pr16573.ll (revision 0)
@@ -0,0 +1,11 @@
+; RUN: llc < %s | FileCheck %s
+
+target triple = "powerpc64-unknown-linux-gnu"
+
+define double @test() {
+ %1 = fptrunc ppc_fp128 0xM818F2887B9295809800000000032D000 to double
+ ret double %1
+}
+
+; CHECK: .quad -9111018957755033591
+
Index: lib/Support/APFloat.cpp
===================================================================
--- lib/Support/APFloat.cpp (revision 185817)
+++ lib/Support/APFloat.cpp (working copy)
@@ -1956,6 +1956,23 @@
X86SpecialNan = true;
}
+ // If this is a truncation of a denormal number, and the target semantics
+ // has larger exponent range than the source semantics (this can happen
+ // when truncating from PowerPC double-double to double format), the
+ // right shift could lose result mantissa bits. Adjust exponent instead
+ // of performing excessive shift.
+ if (shift < 0 && isFiniteNonZero()) {
+ int exponentChange = significandMSB() + 1 - fromSemantics.precision;
+ if (exponent + exponentChange < toSemantics.minExponent)
+ exponentChange = toSemantics.minExponent - exponent;
+ if (exponentChange < shift)
+ exponentChange = shift;
+ if (exponentChange < 0) {
+ shift -= exponentChange;
+ exponent += exponentChange;
+ }
+ }
+
// If this is a truncation, perform the shift before we narrow the storage.
if (shift < 0 && (isFiniteNonZero() || category==fcNaN))
lostFraction = shiftRight(significandParts(), oldPartCount, -shift);
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186409 91177308-0d34-0410-b5e6-96231b3b80d8
Originally if D.firstSigDigit == str.end(), we will have already dereferenced
D.firstSigDigit in the first predicate.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185437 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r185099.
Looks like both the ppc-64 and mips bots are still failing after I reverted this
change.
Since:
1. The mips bot always performs a clean build,
2. The ppc64-bot failed again after a clean build (I asked the ppc-64
maintainers to clean the bot which they did... Thanks Will!),
I think it is safe to assume that this change was not the cause of the failures
that said builders were seeing. Thus I am recomitting.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185111 91177308-0d34-0410-b5e6-96231b3b80d8
Hal Finkel
Benjamin Kramer
Chandler Carruth
Nick Lewycky
Alexey Samsonov
Andrea Di Biagio
Dylan Noblesmith
Stephen Canon
Craig Topper
Alp Toker
Eli Friedman
Ted Kremenek
Michael Gottesman
Ulrich Weigand