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);
llvm-svn: 186409
We'd forgotten to provide string representations for the special ARMISD atomic
nodes; this adds them in. No effect on CodeGen, just makes the output of
"-view-whatever-dags" slightly more readable.
llvm-svn: 186406
This fixes an incorrect detection that led to a formatting error.
Before:
some_var = function (*some_pointer_var)[0];
After:
some_var = function(*some_pointer_var)[0];
llvm-svn: 186402
Another patch in the series to make more use of R.SBG. This one extends
r186072 and r186073 to handle cases where the AND is inside the shift.
llvm-svn: 186399
Unfortunately I don't think there's a good way to validate branch targets on
release builds. Fortunately it's a minor part of this test (and based on
generic code) so I don't mind dropping it.
llvm-svn: 186398
This adds three overloaded intrinsics to Clang:
T __builtin_arm_ldrex(const volatile T *addr)
int __builtin_arm_strex(T val, volatile T *addr)
void __builtin_arm_clrex()
The intent is that these do what users would expect when given most sensible
types. Currently, "sensible" translates to ints, floats and pointers.
llvm-svn: 186394
This patch enables calls to __aeabi_idivmod when in EABI mode,
by using the remainder value returned on registers (R1),
enabled by the ARM triple "none-eabi". Note that Darwin and
GNUEABI triples will continue lowering on GNU style, that is,
using the stack for the remainder.
Still need to add SREM/UREM support fix for 64-bit lowering.
llvm-svn: 186390
This is a follow up patch for r186336.
Reviewers: LegalizeAdulthood
CC: silvas, llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1144
llvm-svn: 186384
This is a micro optimization. Instead of going char*->StringRef->Twine->char*,
go char*->Twine->char* and avoid having to copy the filename on the stack.
llvm-svn: 186380
llvm-ar is the only user of toWin32Time() (via setLastModificationAndAccessTime), and r186298 can be reverted.
It had been buggy since the initial commit.
FIXME: Could we rename {from|to}Win32Time as {from|to}Win32FILETIME in TimeValue?
llvm-svn: 186374
Not completely sure this is right, but it's clearly better than what
we did before this commit (effectively dropping the attribute).
<rdar://problem/14413117>
llvm-svn: 186373
The record layout code didn't properly take into account that
an empty class at offset 0 can have an alignment greater than 1.
Patch by Andrea Di Biagio.
llvm-svn: 186370
Make sure we call BuildFieldReferenceExpr with the appropriate decl
when a member of an anonymous union is made public with a using decl.
Also, fix a crash on invalid field access into an anonymous union.
Fixes PR16630.
llvm-svn: 186367
We can have a FrameSetup in one basic block and the matching FrameDestroy
in a different basic block when we have struct byval. In that case, SPAdj
is not zero at beginning of the basic block.
Modify PEI to correctly set SPAdj at beginning of each basic block using
DFS traversal. We used to assume SPAdj is 0 at beginning of each basic block.
PEI had an assert SPAdjCount || SPAdj == 0.
If we have a Destroy <n> followed by a Setup <m>, PEI will assert failure.
We can add an extra condition to make sure the pairs are matched:
The pairs start with a FrameSetup.
But since we are doing a much better job in the verifier, this patch removes
the check in PEI.
PR16393
llvm-svn: 186364
delete a constant after we replaced it with a
dynamically-computed value. Also ensured that we
replace all users of the constant if there are
multiple ones. Added a testcase.
<rdar://problem/14379043>
llvm-svn: 186363
Added a setting to control timeout for kdp response packets. While I was at it, I also added a way to control the response timeout for gdb-remote packets.
KDP defaults to 5 seconds, and GDB defaults to 1 second. These were the default values that were in the code prior to adding these settings.
(lldb) settings set plugin.process.gdb-remote.packet-timeout 10
(lldb) settings set plugin.process.kdp-remote.packet-timeout 10
llvm-svn: 186360
