pass. This pass should expand with all of the small, fine-grained optimization
passes to reduce compile time and increase happiment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110627 91177308-0d34-0410-b5e6-96231b3b80d8
This pass tries to remove comparison instructions when possible. For instance,
if you have this code:
sub r1, 1
cmp r1, 0
bz L1
and "sub" either sets the same flag as the "cmp" instruction or could be
converted to set the same flag, then we can eliminate the "cmp" instruction all
together. This is a important for ARM where the ALU instructions could set the
CPSR flag, but need a special suffix ('s') to do so.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110423 91177308-0d34-0410-b5e6-96231b3b80d8
be killed before being redefined.
These checks are usually disabled, and usually fail when enabled. We de facto
allow live registers to be redefined without a kill, the corresponding
assertions in RegScavenger were removed long ago.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110362 91177308-0d34-0410-b5e6-96231b3b80d8
optimization level.
This only really affects llc for now because both the llvm-gcc and clang front
ends override the default register allocator. I intend to remove that code later.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@104904 91177308-0d34-0410-b5e6-96231b3b80d8
So far this is just a clone of -regalloc=local that has been lobotomized to run
25% faster. It drops the least-recently-used calculations, and is just plain
stupid when it runs out of registers.
The plan is to make this go even faster for -O0 by taking advantage of the short
live intervals in unoptimized code. It should not be necessary to calculate
liveness when most virtual registers are killed 2-3 instructions after they are
born.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102006 91177308-0d34-0410-b5e6-96231b3b80d8
source addition. Apparently the buildbots were wrong about failures.
---
Add some switches helpful for debugging:
-print-before=<Pass Name>
Dump IR before running pass <Pass Name>.
-print-before-all
Dump IR before running each pass.
-print-after-all
Dump IR after running each pass.
These are helpful when tracking down a miscompilation. It is easy to
get IR dumps and do diffs on them, etc.
To make this work well, add a new getPrinterPass API to Pass so that
each kind of pass (ModulePass, FunctionPass, etc.) can create a Pass
suitable for dumping out the kind of object the Pass works on.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100249 91177308-0d34-0410-b5e6-96231b3b80d8
<string> include. For some reason the buildbot choked on this while my
builds did not. It's probably due to a difference in system headers.
---
Add some switches helpful for debugging:
-print-before=<Pass Name>
Dump IR before running pass <Pass Name>.
-print-before-all
Dump IR before running each pass.
-print-after-all
Dump IR after running each pass.
These are helpful when tracking down a miscompilation. It is easy to
get IR dumps and do diffs on them, etc.
To make this work well, add a new getPrinterPass API to Pass so that
each kind of pass (ModulePass, FunctionPass, etc.) can create a Pass
suitable for dumping out the kind of object the Pass works on.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100204 91177308-0d34-0410-b5e6-96231b3b80d8
-print-before=<Pass Name>
Dump IR before running pass <Pass Name>.
-print-before-all
Dump IR before running each pass.
-print-after-all
Dump IR after running each pass.
These are helpful when tracking down a miscompilation. It is easy to
get IR dumps and do diffs on them, etc.
To make this work well, add a new getPrinterPass API to Pass so that
each kind of pass (ModulePass, FunctionPass, etc.) can create a Pass
suitable for dumping out the kind of object the Pass works on.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100143 91177308-0d34-0410-b5e6-96231b3b80d8
reduce down to a single value. InstCombine already does this transformation
but DAG legalization may introduce new opportunities. This has turned out to
be important for ARM where 64-bit values are split up during type legalization:
InstCombine is not able to remove the PHI cycles on the 64-bit values but
the separate 32-bit values can be optimized. I measured the compile time
impact of this (running llc on 176.gcc) and it was not significant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95951 91177308-0d34-0410-b5e6-96231b3b80d8
function can support dynamic stack realignment. That's a much easier question
to answer at instruction selection stage than whether the function actually
will have dynamic alignment prologue. This allows the removal of the
stack alignment heuristic pass, and improves code quality for cases where
the heuristic would result in dynamic alignment code being generated when
it was not strictly necessary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93885 91177308-0d34-0410-b5e6-96231b3b80d8
For now, this pass is fairly conservative. It only perform the replacement when both the pre- and post- extension values are used in the block. It will miss cases where the post-extension values are live, but not used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93278 91177308-0d34-0410-b5e6-96231b3b80d8
running tail duplication when doing branch folding for if-conversion, and
we also want to be able to run tail duplication earlier to fix some
reg alloc problems. Move the CanFallThrough function from BranchFolding
to MachineBasicBlock so that it can be shared by TailDuplication.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89904 91177308-0d34-0410-b5e6-96231b3b80d8
--- Reverse-merging r85338 into '.':
U lib/CodeGen/SimpleRegisterCoalescing.cpp
U lib/CodeGen/SimpleRegisterCoalescing.h
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85454 91177308-0d34-0410-b5e6-96231b3b80d8
use it to control tail merging when there is a tradeoff between performance
and code size. When there is only 1 instruction in the common tail, we have
been merging. That can be good for code size but is a definite loss for
performance. Now we will avoid tail merging in that case when the
optimization level is "Aggressive", i.e., "-O3". Radar 7338114.
Since the IfConversion pass invokes BranchFolding, it too needs to know
the optimization level. Note that I removed the RegisterPass instantiation
for IfConversion because it required a default constructor. If someone
wants to keep that for some reason, we can add a default constructor with
a hard-wired optimization level.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85346 91177308-0d34-0410-b5e6-96231b3b80d8
more properly belong. This allows removing the front-end conditionalized
SJLJ code, and cleans up the generated IR considerably. All of the
infrastructure code (calling _Unwind_SjLj_Register/Unregister, etc) is
added by the SjLjEHPrepare pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79250 91177308-0d34-0410-b5e6-96231b3b80d8
shouldn't do AU.setPreservesCFG(), because even though CodeGen passes
don't modify the LLVM IR CFG, they may modify the MachineFunction CFG,
and passes like MachineLoop are registered with isCFGOnly set to true.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77691 91177308-0d34-0410-b5e6-96231b3b80d8
failures when building assorted projects with clang.
--- Reverse-merging r77654 into '.':
U include/llvm/CodeGen/Passes.h
U include/llvm/CodeGen/MachineFunctionPass.h
U include/llvm/CodeGen/MachineFunction.h
U include/llvm/CodeGen/LazyLiveness.h
U include/llvm/CodeGen/SelectionDAGISel.h
D include/llvm/CodeGen/MachineFunctionAnalysis.h
U include/llvm/Function.h
U lib/Target/CellSPU/SPUISelDAGToDAG.cpp
U lib/Target/PowerPC/PPCISelDAGToDAG.cpp
U lib/CodeGen/LLVMTargetMachine.cpp
U lib/CodeGen/MachineVerifier.cpp
U lib/CodeGen/MachineFunction.cpp
U lib/CodeGen/PrologEpilogInserter.cpp
U lib/CodeGen/MachineLoopInfo.cpp
U lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
D lib/CodeGen/MachineFunctionAnalysis.cpp
D lib/CodeGen/MachineFunctionPass.cpp
U lib/CodeGen/LiveVariables.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77661 91177308-0d34-0410-b5e6-96231b3b80d8
code in preparation for code generation. The main thing it does
is handle the case when eh.exception calls (and, in a future
patch, eh.selector calls) are far away from landing pads. Right
now in practice you only find eh.exception calls close to landing
pads: either in a landing pad (the common case) or in a landing
pad successor, due to loop passes shifting them about. However
future exception handling improvements will result in calls far
from landing pads:
(1) Inlining of rewinds. Consider the following case:
In function @f:
...
invoke @g to label %normal unwind label %unwinds
...
unwinds:
%ex = call i8* @llvm.eh.exception()
...
In function @g:
...
invoke @something to label %continue unwind label %handler
...
handler:
%ex = call i8* @llvm.eh.exception()
... perform cleanups ...
"rethrow exception"
Now inline @g into @f. Currently this is turned into:
In function @f:
...
invoke @something to label %continue unwind label %handler
...
handler:
%ex = call i8* @llvm.eh.exception()
... perform cleanups ...
invoke "rethrow exception" to label %normal unwind label %unwinds
unwinds:
%ex = call i8* @llvm.eh.exception()
...
However we would like to simplify invoke of "rethrow exception" into
a branch to the %unwinds label. Then %unwinds is no longer a landing
pad, and the eh.exception call there is then far away from any landing
pads.
(2) Using the unwind instruction for cleanups.
It would be nice to have codegen handle the following case:
invoke @something to label %continue unwind label %run_cleanups
...
handler:
... perform cleanups ...
unwind
This requires turning "unwind" into a library call, which
necessarily takes a pointer to the exception as an argument
(this patch also does this unwind lowering). But that means
you are using eh.exception again far from a landing pad.
(3) Bugpoint simplifications. When bugpoint is simplifying
exception handling code it often generates eh.exception calls
far from a landing pad, which then causes codegen to assert.
Bugpoint then latches on to this assertion and loses sight
of the original problem.
Note that it is currently rare for this pass to actually do
anything. And in fact it normally shouldn't do anything at
all given the code coming out of llvm-gcc! But it does fire
a few times in the testsuite. As far as I can see this is
almost always due to the LoopStrengthReduce codegen pass
introducing pointless loop preheader blocks which are landing
pads and only contain a branch to another block. This other
block contains an eh.exception call. So probably by tweaking
LoopStrengthReduce a bit this can be avoided.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72276 91177308-0d34-0410-b5e6-96231b3b80d8
The following is checked:
* Operand counts: All explicit operands must be present.
* Register classes: All physical and virtual register operands must be
compatible with the register class required by the instruction descriptor.
* Register live intervals: Registers must be defined only once, and must be
defined before use.
The machine code verifier is enabled with the command-line option
'-verify-machineinstrs', or by defining the environment variable
LLVM_VERIFY_MACHINEINSTRS to the name of a file that will receive all the
verifier errors.
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- Use enums instead of magic numbers.
- Rework algorithm to use the bytes size from the target to determine when to
emit stack protectors.
- Get rid of "propolice" in any comments.
- Renamed an option to its expanded form.
- Other miscellanenous changes.
More changes will come after this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58723 91177308-0d34-0410-b5e6-96231b3b80d8
* The prologue is modified to read the __stack_chk_guard global and insert it
onto the stack.
* The epilogue is modified to read the stored guard from the stack and compare
it to the original __stack_chk_guard value. If they differ, then the
__stack_chk_fail() function is called.
* The stack protector needs to be first on the stack (after the parameters) to
catch any stack-smashing activities.
Front-end support will follow after a round of beta testing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58673 91177308-0d34-0410-b5e6-96231b3b80d8
