When debugging performance regressions we often ask ourselves if the regression
that we see is due to poor isel/sched/ra or due to some micro-architetural
problem. When comparing two code sequences one good way to rule out front-end
bottlenecks (and other the issues) is to force code alignment. This pass adds
a flag that forces the alignment of all of the basic blocks in the program.
llvm-svn: 179353
As packed comparisons in AVX/SSE produce all 0s or all 1s in each SIMD lane,
vector select could be simplified to AND/OR or removed if one or both values
being selected is all 0s or all 1s.
llvm-svn: 179267
This patch is revised based on patch from Victor Umansky
<victor.umansky@intel.com>. More cases are handled in X86's bool
simplification, i.e.
- SETCC_CARRY
- value is truncated to i1 with AND
As a by-product, PR5443 is also fixed.
llvm-svn: 179265
In the simple and triangle if-conversion cases, when CopyAndPredicateBlock is
used because the to-be-predicated block has other predecessors, we need to
explicitly remove the old copied block from the successors list. Normally if
conversion relies on TII->AnalyzeBranch combined with BB->CorrectExtraCFGEdges
to cleanup the successors list, but if the predicated block contained an
un-analyzable branch (such as a now-predicated return), then this will fail.
These extra successors were causing a problem on PPC because it was causing
later passes (such as PPCEarlyReturm) to leave dead return-only basic blocks in
the code.
llvm-svn: 179227
Mips32 code as Mips16 unless it can't be compiled as Mips 16. For now this
would happen as long as floating point instructions are not needed.
Probably it would also make sense to compile as mips32 if atomic operations
are needed too. There may be other cases too.
A module pass prescans the IR and adds the mips16 or nomips16 attribute
to functions depending on the functions needs.
Mips 16 mode can result in a 40% code compression by utililizing 16 bit
encoding of many instructions.
The hope is for this to replace the traditional gcc way of dealing with
Mips16 code using floating point which involves essentially using soft float
but with a library implemented using mips32 floating point. This gcc
method also requires creating stubs so that Mips32 code can interact with
these Mips 16 functions that have floating point needs. My conjecture is
that in reality this traditional gcc method would never win over this
new method.
I will be implementing the traditional gcc method also. Some of it is already
done but I needed to do the stubs to finish the work and those required
this mips16/32 mixed mode capability.
I have more ideas for to make this new method much better and I think the old
method will just live in llvm for anyone that needs the backward compatibility
but I don't for what reason that would be needed.
llvm-svn: 179185
Depending on the number of bits set in the writemask.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>
llvm-svn: 179166
Modifier 'D' is to use the second word of a double integer.
We had previously implemented the pure register varient of
the modifier and this patch implements the memory reference.
#include "stdio.h"
int b[8] = {0,1,2,3,4,5,6,7};
void main()
{
int i;
// The first word. Notice, no 'D'
{asm (
"lw %0,%1;"
: "=r" (i)
: "m" (*(b+4))
);}
printf("%d\n",i);
// The second word
{asm (
"lw %0,%D1;"
: "=r" (i)
: "m" (*(b+4))
);}
printf("%d\n",i);
}
llvm-svn: 179135
This enables us to form predicated branches (which are the same conditional
branches we had before) and also a larger set of predicated returns (including
instructions like bdnzlr which is a conditional return and loop-counter
decrement all in one).
At the moment, if conversion does not capture all possible opportunities. A
simple example is provided in early-ret2.ll, where if conversion forms one
predicated return, and then the PPCEarlyReturn pass picks up the other one. So,
at least for now, we'll keep both mechanisms.
llvm-svn: 179134
and mips16 on a per function basis.
Because this patch is somewhat involved I have provide an overview of the
key pieces of it.
The patch is written so as to not change the behavior of the non mixed
mode. We have tested this a lot but it is something new to switch subtargets
so we don't want any chance of regression in the mainline compiler until
we have more confidence in this.
Mips32/64 are very different from Mip16 as is the case of ARM vs Thumb1.
For that reason there are derived versions of the register info, frame info,
instruction info and instruction selection classes.
Now we register three separate passes for instruction selection.
One which is used to switch subtargets (MipsModuleISelDAGToDAG.cpp) and then
one for each of the current subtargets (Mips16ISelDAGToDAG.cpp and
MipsSEISelDAGToDAG.cpp).
When the ModuleISel pass runs, it determines if there is a need to switch
subtargets and if so, the owning pointers in MipsTargetMachine are
appropriately changed.
When 16Isel or SEIsel is run, they will return immediately without doing
any work if the current subtarget mode does not apply to them.
In addition, MipsAsmPrinter needs to be reset on a function basis.
The pass BasicTargetTransformInfo is substituted with a null pass since the
pass is immutable and really needs to be a function pass for it to be
used with changing subtargets. This will be fixed in a follow on patch.
llvm-svn: 179118
This pattern occurs in SROA output due to the way vector arguments are lowered
on ARM.
The testcase from PR15525 now compiles into this, which is better than the code
we got with the old scalarrepl:
_Store:
ldr.w r9, [sp]
vmov d17, r3, r9
vmov d16, r1, r2
vst1.8 {d16, d17}, [r0]
bx lr
Differential Revision: http://llvm-reviews.chandlerc.com/D647
llvm-svn: 179106
On PowerPC, non-vector loads and stores have r+i forms; however, in functions
with large stack frames these were not being used to access slots far from the
stack pointer because such slots were out of range for the signed 16-bit
immediate offset field. This increases register pressure because we need a
separate register for each offset (when the r+r form is used). By enabling
virtual base registers, we can deal with large stack frames without unduly
increasing register pressure.
llvm-svn: 179105
The save area is twice as big and there is no struct return slot. The
stack pointer is always 16-byte aligned (after adding the bias).
Also eliminate the stack adjustment instructions around calls when the
function has a reserved stack frame.
llvm-svn: 179083
PowerPC has a conditional branch to the link register (return) instruction: BCLR.
This should be used any time when we'd otherwise have a conditional branch to a
return. This adds a small pass, PPCEarlyReturn, which runs just prior to the
branch selection pass (and, importantly, after block placement) to generate
these conditional returns when possible. It will also eliminate unconditional
branches to returns (these happen rarely; most of the time these have already
been tail duplicated by the time PPCEarlyReturn is invoked). This is a nice
optimization for small functions that do not maintain a stack frame.
llvm-svn: 179026
I've managed to convince myself that AArch64's acquire/release
instructions are sufficient to guarantee C++11's required semantics,
even in the sequentially-consistent case.
llvm-svn: 179005
First, we should not cheat: fsel-based lowering of select_cc is a
finite-math-only optimization (the ISA manual, section F.3 of v2.06, makes
this clear, as does a note in our own README).
This also adds fsel-based lowering of EQ and NE condition codes. As it turned
out, fsel generation was covered by a grand total of zero regression test
cases. I've added some test cases to cover the existing behavior (which is now
finite-math only), as well as the new EQ cases.
llvm-svn: 179000
Integer return values are sign or zero extended by the callee, and
structs up to 32 bytes in size can be returned in registers.
The CC_Sparc64 CallingConv definition is shared between
LowerFormalArguments_64 and LowerReturn_64. Function arguments and
return values are passed in the same registers.
The inreg flag is also used for return values. This is required to handle
C functions returning structs containing floats and ints:
struct ifp {
int i;
float f;
};
struct ifp f(void);
LLVM IR:
define inreg { i32, float } @f() {
...
ret { i32, float } %retval
}
The ABI requires that %retval.i is returned in the high bits of %i0
while %retval.f goes in %f1.
Without the inreg return value attribute, %retval.i would go in %i0 and
%retval.f would go in %f3 which is a more efficient way of returning
%multiple values, but it is not ABI compliant for returning C structs.
llvm-svn: 178966
64-bit SPARC v9 processes use biased stack and frame pointers, so the
current function's stack frame is located at %sp+BIAS .. %fp+BIAS where
BIAS = 2047.
This makes more local variables directly accessible via [%fp+simm13]
addressing.
llvm-svn: 178965
There are certain PPC instructions into which we can fold a zero immediate
operand. We can detect such cases by looking at the register class required
by the using operand (so long as it is not otherwise constrained).
llvm-svn: 178961
All arguments are formally assigned to stack positions and then promoted
to floating point and integer registers. Since there are more floating
point registers than integer registers, this can cause situations where
floating point arguments are assigned to registers after integer
arguments that where assigned to the stack.
Use the inreg flag to indicate 32-bit fragments of structs containing
both float and int members.
The three-way shadowing between stack, integer, and floating point
registers requires custom argument lowering. The good news is that
return values are passed in the exact same way, and we can share the
code.
Still missing:
- Update LowerReturn to handle structs returned in registers.
- LowerCall.
- Variadic functions.
llvm-svn: 178958
SITargetLowering::analyzeImmediate() was converting the 64-bit values
to 32-bit and then checking if they were an inline immediate. Some
of these conversions caused this check to succeed and produced
S_MOV instructions with 64-bit immediates, which are illegal.
v2:
- Clean up logic
Reviewed-by: Christian König <christian.koenig@amd.com>
llvm-svn: 178927
On cores for which we know the misprediction penalty, and we have
the isel instruction, we can profitably perform early if conversion.
This enables us to replace some small branch sequences with selects
and avoid the potential stalls from mispredicting the branches.
Enabling this feature required implementing canInsertSelect and
insertSelect in PPCInstrInfo; isel code in PPCISelLowering was
refactored to use these functions as well.
llvm-svn: 178926
The DAGCombine logic that recognized a/sqrt(b) and transformed it into
a multiplication by the reciprocal sqrt did not handle cases where the
sqrt and the division were separated by an fpext or fptrunc.
llvm-svn: 178801
The Thumb2SizeReduction pass avoids false CPSR dependencies, except it
still aggressively creates tMOVi8 instructions because they are so
common.
Avoid creating false CPSR dependencies even for tMOVi8 instructions when
the the CPSR flags are known to have high latency. This allows integer
computation to overlap floating point computations.
Also process blocks in a reverse post-order and propagate high-latency
flags to successors.
<rdar://problem/13468102>
llvm-svn: 178773
This requires v9 cmov instructions using the %xcc flags instead of the
%icc flags.
Still missing:
- Select floats on %xcc flags.
- Select i64 on %fcc flags.
llvm-svn: 178737
For this we need to use a libcall. Previously LLVM didn't implement
libcall support for frem, so I've added it in the usual
straightforward manner. A test case from the bug report is included.
llvm-svn: 178639
Nadav Rotem