live across BBs before register allocation. This miscompiled 197.parser
when a cmp + b are optimized to a cbnz instruction even though the CPSR def
is live-in a successor.
cbnz r6, LBB89_12
...
LBB89_12:
ble LBB89_1
The fix consists of two parts. 1) Teach LiveVariables that some unallocatable
registers might be liveouts so don't mark their last use as kill if they are.
2) ARM constantpool island pass shouldn't form cbz / cbnz if the conditional
branch does not kill CPSR.
rdar://10676853
llvm-svn: 148168
This function runs after all constant islands have been placed, and may
shrink some instructions to their 2-byte forms. This can actually cause
some constant pool entries to move out of range because of growing
alignment padding.
Treat instructions that may be shrunk the same as inline asm - they
erode the known alignment bits.
Also reinstate an old assertion in verify(). It is correct now that
basic block offsets include alignments.
Add a single large test case that will hopefully exercise many parts of
the constant island pass.
<rdar://problem/10670199>
llvm-svn: 147885
On Thumb, the displacement computation hardware uses the address of the
current instruction rouned down to a multiple of 4. Include this
rounding in the UserOffset we compute for each instruction.
When inline asm is present, the instruction alignment may not be known.
Constrain the maximum displacement instead in that case.
This makes it possible for CreateNewWater() and OffsetIsInRange() to
agree about the valid displacements. When they disagree, infinite
looping happens.
As always, test cases for this stuff are insane.
<rdar://problem/10660175>
llvm-svn: 147825
This adjustment is already included in the block offsets computed by
BasicBlockInfo, and adjusting again here can cause the pass to loop.
When CreateNewWater splits a basic block, OffsetIsInRange would reject
the new CPE on the next pass because of the too conservative alignment
adjustment. This caused the block to be split again, and so on.
llvm-svn: 146751
The command line option should be removed, but not until the feature has
gotten a lot of testing. The ARMConstantIslandPass tends to have subtle
bugs that only show up after a while.
llvm-svn: 146739
An aligned constant pool entry may require extra alignment padding where
the new water is created. Take that into account when computing offset.
Also consider the alignment of other constant pool entries when
splitting a basic block. Alignment padding may make it necessary to
move the split point higher.
llvm-svn: 146609
Constant pool entries with different alignment may cause more alignment
padding to be inserted. Compute the amount of padding needed, and try to
pick the location that requires the least amount of padding.
Also take the extra padding into account when the water is above the
use.
llvm-svn: 146458
Downgrade the alignment of the initial constant island when constant
pool entries are moved elsewhere.
This is all gated by -arm-align-constant-islands.
llvm-svn: 146391
Order constant pool entries by descending alignment in the initial
island to ensure packing and correct alignment. When the command line
flag is set, also align the basic block containing the constant pool
entries.
This is only a partial implementation of constant island alignment. More
to come.
llvm-svn: 146375
The split point is picked such that the newly created water has the same
alignment as the function. This makes the island suitable for constant
pool entries with potentially higher alignment.
This also fixes an issue where the basic block was split one instruction
too late, causing nonconvergence of the algorithm.
<rdar://problem/10550705>
There is still an issue with correctly packing differently aligned
entries in the island.
llvm-svn: 146314
It is not used any more. We are tracking inline assembly misalignments
directly through the BBInfo.Unalign and KnownBits fields.
A simple conservative size estimate is not good enough since it can
cause alignment padding to be underestimated.
llvm-svn: 146124
Compute alignment padding before and after basic blocks dynamically.
Heed basic block alignment.
This simplifies bookkeeping because we don't have to constantly add and
remove padding from BBInfo.Size. It also makes it possible to track the
extra known alignment bits we get after a tBR_JTr terminator and when
entering an aligned basic block.
This makes the ARMConstantIslandPass aware of aligned basic blocks.
It is tricky to model block alignment correctly when dealing with inline
assembly and tBR_JTr instructions that have variable size. If inline
assembly turns out to be smaller than expected, that may cause following
alignment padding to be larger than expected. This could cause constant
pool entries to move out of range.
To avoid that problem, we use the worst case alignment padding following
inline assembly. This may cause slightly suboptimal constant island
placement in aligned basic blocks following inline assembly. Normal
functions should be unaffected.
llvm-svn: 146118
generator to it. For non-bundle instructions, these behave exactly the same
as the MC layer API.
For properties like mayLoad / mayStore, look into the bundle and if any of the
bundled instructions has the property it would return true.
For properties like isPredicable, only return true if *all* of the bundled
instructions have the property.
For properties like canFoldAsLoad, isCompare, conservatively return false for
bundles.
llvm-svn: 146026
The block offset can be computed from the previous block. That is more
robust than keeping track of a delta.
Eliminate one redundant AdjustBBOffsetsAfter call.
llvm-svn: 146018
This pseudo-instruction contains a .align directive in its expansion, so
the total size may vary by 2 bytes.
It is too difficult to accurately keep track of this alignment
directive, just use the worst-case size instead.
llvm-svn: 145971
ARMConstantIslandPass may sometimes leave empty constant islands behind
(it really shouldn't). Remove the alignment from the empty islands so
the size calculations are still correct.
This should fix the many Thumb1 assembler errors in the nightly test
suite.
The reduced test case for this problem is way too big. That is to be
expected for ARMConstantIslandPass bugs.
<rdar://problem/10534709>
llvm-svn: 145970
Previously, all ARM::CONSTPOOL_ENTRY instructions had a hardwired
alignment of 4 bytes emitted by ARMAsmPrinter. Now the same alignment
is set on the basic block.
This is in preparation of supporting ARM constant pool islands with
different alignments.
llvm-svn: 145890
Original Log: Get rid of the separate opcodes for the Darwin versions of tBL, tBLXi, and tBLXr, using pseudo-instructions to lower to the single final opcode. Update the ARM disassembler for this change.
llvm-svn: 135414
The normal tBX instruction is predicable, so there's no reason the
pseudos for using it as a return shouldn't be. Gives us some nice code-gen
improvements as can be seen by the test changes. In particular, several
tests now have to disable if-conversion because it works too well and defeats
the test.
llvm-svn: 134746
sink them into MC layer.
- Added MCInstrInfo, which captures the tablegen generated static data. Chang
TargetInstrInfo so it's based off MCInstrInfo.
llvm-svn: 134021
t2LDRpci with t2LDRi12.
There are a couple of problems with this.
1. The encoding for the literal and immediate constant are different.
Note bit 7 of the literal case is 'U' so it can be negative.
2. t2LDRi12 is now narrowed to tLDRpci before constant island pass is run.
So we end up never using the Thumb2 instruction, which ends up creating a
lot more constant islands.
llvm-svn: 125074
movw r0, :lower16:(L_foo$non_lazy_ptr-(LPC0_0+4))
movt r0, :upper16:(L_foo$non_lazy_ptr-(LPC0_0+4))
LPC0_0:
add r0, pc, r0
It's not yet enabled by default as some tests are failing. I suspect bugs in
down stream tools.
llvm-svn: 123619
Jim Grosbach