This code:
float floatingPointComparison(float x, float y) {
double product = (double)x * y;
if (product == 0.0)
return product;
return product - 1.0;
}
produces this:
_floatingPointComparison:
0000000000000000 cvtss2sd %xmm1,%xmm1
0000000000000004 cvtss2sd %xmm0,%xmm0
0000000000000008 mulsd %xmm1,%xmm0
000000000000000c pxor %xmm1,%xmm1
0000000000000010 ucomisd %xmm1,%xmm0
0000000000000014 jne 0x00000004
0000000000000016 jp 0x00000002
0000000000000018 jmp 0x00000008
000000000000001a addsd 0x00000006(%rip),%xmm0
0000000000000022 cvtsd2ss %xmm0,%xmm0
0000000000000026 ret
The "jne/jp/jmp" sequence can be reduced to this instead:
_floatingPointComparison:
0000000000000000 cvtss2sd %xmm1,%xmm1
0000000000000004 cvtss2sd %xmm0,%xmm0
0000000000000008 mulsd %xmm1,%xmm0
000000000000000c pxor %xmm1,%xmm1
0000000000000010 ucomisd %xmm1,%xmm0
0000000000000014 jp 0x00000002
0000000000000016 je 0x00000008
0000000000000018 addsd 0x00000006(%rip),%xmm0
0000000000000020 cvtsd2ss %xmm0,%xmm0
0000000000000024 ret
for a savings of 2 bytes.
This xform can happen when we recognize that jne and jp jump to the same "true"
MBB, the unconditional jump would jump to the "false" MBB, and the "true" branch
is the fall-through MBB.
llvm-svn: 97766
as nounwind are marked with a -1 call-site value. This is necessary to, for
example, correctly process exceptions thrown from within an "unexpected"
execption handler (see SingleSource/Regression/C++/EH/expection_spec_test.cpp).
llvm-svn: 97757
an undef value. This is only going to come up for bugpoint-reduced tests --
correct programs will not access memory at undefined addresses -- so it's not
worth the effort of doing anything more aggressive.
llvm-svn: 97745
These instructions technically define AL,AH, but a trick in X86ISelDAGToDAG
reads AX in order to avoid reading AH with a REX instruction.
Fix PR6489.
llvm-svn: 97742
just count references to it from JIT output to decide when to destroy it. This
patch waits to destroy the JIT's memory of a stub until the Function it refers
to is destroyed. External function stubs and GVIndirectSyms aren't destroyed
until the JIT itself is.
llvm-svn: 97737
Clang's support for weakref is now better than llvm-gcc's :-)
We don't introduce a new symbol and we correctly mark undefined references weak only if there is no
definition or regular undefined references in the same file.
llvm-svn: 97733
Instruction (PLI) for disassembly only.
According to A8.6.120 PLI (immediate, literal), for example, different
instructions are generated for "pli [pc, #0]" and "pli [pc, #-0"]. The
disassembler solves it by mapping -0 (negative zero) to -1, -1 to -2, ..., etc.
llvm-svn: 97731
IF(condition(value)):
If the value satisfies the condition, the line is processed by lit; otherwise
it is skipped. A test with no unignored directives is resolved as Unsupported.
The test suite is responsible for defining conditions; conditions are unary
functions over strings. I've defined two conditions in the LLVM test suite,
TARGET (with values like those in TARGETS_TO_BUILD) and BINDING (with values
like those in llvm_bindings). So for example you can write:
IF(BINDING(ocaml)): RUN: %blah %s -o -
and the RUN line will only execute if LLVM was configured with the ocaml
bindings.
llvm-svn: 97726
Zhongxing Xu