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Commit Graph

10152 Commits

Author SHA1 Message Date
Dan Gohman
aab60a27fc INTRINSIC_W_CHAIN and INTRINSIC_VOID do not use MemSDNode. They
may access memory, but they don't carry a MachineMemOperand.

llvm-svn: 83449
2009-10-07 03:00:18 +00:00
Devang Patel
1639c0e45a Add support to handle debug info attached to an instruction.
This is not yet enabled.

llvm-svn: 83400
2009-10-06 18:37:31 +00:00
Dan Gohman
560feba5c2 Make LLVMContext's pImpl member const.
llvm-svn: 83393
2009-10-06 17:43:57 +00:00
Chris Lattner
e87add4b88 remove predicate simplifier, it never got the last bugs beaten
out of it, and jump threading, condprop and gvn are now getting
most of the benefit.  This was approved by Nicholas and Nicolas.

llvm-svn: 83390
2009-10-06 16:59:46 +00:00
Duncan Sands
2400ad7236 Introduce and use convenience methods for getting pointer types
where the element is of a basic builtin type.  For example, to get
an i8* use getInt8PtrTy.

llvm-svn: 83379
2009-10-06 15:40:36 +00:00
Devang Patel
a8f35ac640 Update processDebugLoc() so that it can be used to process debug info before and after printing an instruction.
llvm-svn: 83363
2009-10-06 02:19:11 +00:00
Jim Grosbach
d6da133b85 In Thumb1, the register scavenger is not always able to use an emergency
spill slot. When frame references are via the frame pointer, they will be
negative, but Thumb1 load/store instructions only allow positive immediate
offsets. Instead, Thumb1 will spill to R12.

llvm-svn: 83336
2009-10-05 22:30:23 +00:00
Dan Gohman
176e47a413 Remove an unnnecessary LLVMContext argument in
ConstantFoldLoadThroughGEPConstantExpr.

llvm-svn: 83311
2009-10-05 16:36:26 +00:00
Dan Gohman
1b6c3b40ec Fix a name in a comment.
llvm-svn: 83306
2009-10-05 15:23:17 +00:00
Chris Lattner
8afd7dbdaa add more type predicates.
llvm-svn: 83296
2009-10-05 05:48:40 +00:00
Chris Lattner
30e2de19c7 add some helper functions.
llvm-svn: 83293
2009-10-05 05:05:57 +00:00
Chris Lattner
1aa661ce46 remove llvm-db: it is completely broken and if anyone wants to do a debugger,
they should not base it on llvm-db (which not following almost any "best practices").

llvm-svn: 83288
2009-10-05 02:29:51 +00:00
Owen Anderson
412df08b59 Do away with the strange use of BitVectors in SSI, and just use normal sets. This makes the code much more C++/LLVM-ish.
llvm-svn: 83286
2009-10-04 18:49:55 +00:00
Evan Cheng
1a5c370be3 Rename enum NumOccurrences to NumOccurrencesFlag since there is a member named NumOccurrences.
llvm-svn: 83273
2009-10-04 05:25:42 +00:00
Lang Hames
f6903a7043 Renamed MachineInstrIndex to LiveIndex.
llvm-svn: 83254
2009-10-03 04:21:37 +00:00
Mike Stump
532ed49e39 Expand api out in the usual inserter way, though, I do have a
question, can we get rid of the BasicBlock versions of all inserters
and use Head == 0 to indicate the old case when GetInsertBlock == 0?

llvm-svn: 83216
2009-10-01 22:08:58 +00:00
Jim Grosbach
f106b9ad37 remove trailing whitespace
llvm-svn: 83213
2009-10-01 20:45:06 +00:00
Dan Gohman
7cdf41cf01 Don't use identifiers that start with an underscore followed
by a capital letter, which invokes undefined behavior.

llvm-svn: 83206
2009-10-01 17:39:52 +00:00
Douglas Gregor
a3fb17c280 Teach CMake to look for bidirectional_iterator, iterator, forward_iterator, uint64_t, and u_int64_t, from Yonggang Luo
llvm-svn: 83203
2009-10-01 17:25:36 +00:00
Evan Cheng
8ea3f4a592 Add instruction flags: hasExtraSrcRegAllocReq and hasExtraDefRegAllocReq. When
set, these flags indicate the instructions source / def operands have special
register allocation requirement that are not captured in their register classes.
Post-allocation passes (e.g. post-alloc scheduler) should not change their
allocations. e.g. ARM::LDRD require the two definitions to be allocated
even / odd register pair.

llvm-svn: 83196
2009-10-01 08:21:18 +00:00
Chris Lattner
857ed445a8 remove the GVNPRE pass. It has been subsumed by the GVN pass.
Ok'd by Owen.

llvm-svn: 83193
2009-10-01 02:18:36 +00:00
Devang Patel
4f1147e386 Add another MDNode into DebugLocTuple. This will be used to keep track of inlined functions.
llvm-svn: 83190
2009-10-01 01:15:28 +00:00
Devang Patel
d24ba7a101 If location info is attached with an instruction then keep track of alloca slots used by a variable. This info will be used by AsmPrinter to emit debug info for variables.
llvm-svn: 83189
2009-10-01 01:03:26 +00:00
Devang Patel
e097bf49d0 Use MachineInstr as an processDebugLoc() argument.
This will allow processDebugLoc() to handle scopes for DWARF debug info. 

llvm-svn: 83183
2009-09-30 23:12:50 +00:00
Devang Patel
044648c2d7 Use MDNode * directly as an RecordSourceLine() argument.
llvm-svn: 83182
2009-09-30 22:51:28 +00:00
Devang Patel
ef84ca6011 Remove dead code.
llvm-svn: 83181
2009-09-30 22:43:52 +00:00
Devang Patel
cb516787d0 Add isFOO() helpers. Fix getDirectory() and getFilename() for DIScope.
llvm-svn: 83180
2009-09-30 22:34:41 +00:00
Bob Wilson
d6896006b1 Use OutStreamer.SwitchSection instead of writing out textual section directives.
Add a new TargetLoweringObjectFileMachO::getConstTextCoalSection method to
get access to that section.

llvm-svn: 83178
2009-09-30 22:25:37 +00:00
Bob Wilson
1cf44c8225 Add a new virtual EmitStartOfAsmFile method to the AsmPrinter and use this
to emit target-specific things at the beginning of the asm output.  This
fixes a problem for PPC, where the text sections are not being kept together
as expected.  The base class doInitialization code calls DW->BeginModule()
which emits a bunch of DWARF section directives.  The PPC doInitialization
code then emits all the TEXT section directives, with the intention that they
will be kept together. But as I understand it, the Darwin assembler treats
the default TEXT section as a special case and moves it to the beginning of
the file, which means that all those DWARF sections are in the middle of
the text.  With this change, the EmitStartOfAsmFile hook is called before
the DWARF section directives are emitted, so that all the PPC text section
directives come out right at the beginning of the file.

llvm-svn: 83176
2009-09-30 22:06:26 +00:00
Reid Kleckner
ffe2b97d7a Fix integer overflow in instruction scheduling. This can happen if we have
basic blocks that are so long that their size overflows a short.

Also assert that overflow does not happen in the future, as requested by Evan.

This fixes PR4401.

llvm-svn: 83159
2009-09-30 20:15:38 +00:00
Devang Patel
5d5d1f31b7 Silence unused variable warning.
llvm-svn: 83151
2009-09-30 17:13:41 +00:00
Evan Cheng
bb0561f2dd Add a target hook to add pre- post-regalloc scheduling passes.
llvm-svn: 83144
2009-09-30 08:49:50 +00:00
Devang Patel
0136a7ebec Simplify.
llvm-svn: 83123
2009-09-30 00:14:40 +00:00
David Goodwin
a282690f82 Remove -post-RA-schedule flag and add a TargetSubtarget method to enable post-register-allocation scheduling. By default it is off. For ARM, enable/disable with -mattr=+/-postrasched. Enable by default for cortex-a8.
llvm-svn: 83122
2009-09-30 00:10:16 +00:00
Douglas Gregor
66fc2ea1c2 Forward-declare ValueSymbolTable so that SymbolTableListTraits.h can be parsed by itself
llvm-svn: 83121
2009-09-30 00:08:25 +00:00
Mike Stump
a3bce35a07 Add a way for a frontend to generate more complex dwarf location
information.  This allows arbitrary code involving DW_OP_plus_uconst
and DW_OP_deref.  The scheme allows for easy extention to include,
any, or all of the DW_OP_ opcodes.  I thought about just exposing all
of them, but, wasn't sure if people wanted the dwarf opcodes exposed
in the api.  Is that a layering violation?

With this scheme, the entire existing block scheme used by llvm-gcc
can be switched over to the new scheme.  I think that would be
cleaner, as then the compiler specific bits are not present in llvm
proper.  Before the old code can be yanked however, similar code in
clang would have to be removed.

Next up, more testing.

llvm-svn: 83120
2009-09-30 00:08:22 +00:00
Devang Patel
39b5b72d74 Add removeMD().
llvm-svn: 83107
2009-09-29 20:42:25 +00:00
Devang Patel
292bcd8ca1 Only one custom meadata of each kind can be attached with an instruction.
llvm-svn: 83105
2009-09-29 20:30:57 +00:00
Devang Patel
e5be8e79df Remove std::string uses from DebugInfo interface.
llvm-svn: 83083
2009-09-29 18:40:58 +00:00
Devang Patel
5cad2b8f0f Create empty StringRef is incoming cstring is NULL.
llvm-svn: 83082
2009-09-29 18:39:56 +00:00
Devang Patel
629ad89954 Parse custom metadata attached with an instruction.
llvm-svn: 83033
2009-09-29 00:01:14 +00:00
Dan Gohman
74e63461d2 Add C API calls for building FNeg operations. Patch by KS Sreeram!
llvm-svn: 83021
2009-09-28 21:51:41 +00:00
Devang Patel
1070b7a713 s/class Metadata/class MetadataContext/g
llvm-svn: 83019
2009-09-28 21:41:20 +00:00
Devang Patel
d836a7d651 Do not use global typedef for MDKindID.
llvm-svn: 83016
2009-09-28 21:14:55 +00:00
Devang Patel
3c6697dbb6 Remove unnecessary include.
llvm-svn: 83013
2009-09-28 21:06:38 +00:00
Jakob Stoklund Olesen
31fcbdefbb Introduce the TargetInstrInfo::KILL machine instruction and get rid of the
unused DECLARE instruction.

KILL is not yet used anywhere, it will replace TargetInstrInfo::IMPLICIT_DEF
in the places where IMPLICIT_DEF is just used to alter liveness of physical
registers.

llvm-svn: 83006
2009-09-28 20:32:26 +00:00
Dan Gohman
f31dae3931 Convert LoopSimplify and LoopExtractor from FunctionPass to LoopPass.
llvm-svn: 82990
2009-09-28 14:37:51 +00:00
Mikhail Glushenkov
b676fc15a0 Add a way to query the number of input files.
llvm-svn: 82957
2009-09-28 01:16:42 +00:00
Dan Gohman
bd50ec69e4 Move the dominator verification code out of special code embedded within
the PassManager code into a regular verifyAnalysis method.

Also, reorganize loop verification. Make the LoopPass infrastructure
call verifyLoop as needed instead of having LoopInfo::verifyAnalysis
check every loop in the function after each looop pass. Add a new
command-line argument, -verify-loop-info, to enable the expensive
full checking.

llvm-svn: 82952
2009-09-28 00:27:48 +00:00
Dan Gohman
09f5f7f190 Extend the StartPassTimer and StopPassTimer functions so that the
code that stops the timer doesn't have to search to find the timer
object before it stops the timer. This avoids a lock acquisition
and a few other things done with the timer running.

llvm-svn: 82949
2009-09-28 00:07:05 +00:00
Dan Gohman
db89691ec4 Extract the code for inserting a loop into the loop queue into
a separate function.

llvm-svn: 82946
2009-09-27 23:49:43 +00:00
Dan Gohman
fdd9a2ee96 Extract the code for releasing a pass into a separate function, and
tidy it up a little.

llvm-svn: 82944
2009-09-27 23:38:27 +00:00
Nick Lewycky
81504d2150 Round out the API for the new optimization flags.
llvm-svn: 82930
2009-09-27 21:33:04 +00:00
Tilmann Scheller
a23802520a Use explicit structs instead of std::pair to map callee saved regs to spill slots.
llvm-svn: 82909
2009-09-27 17:58:47 +00:00
Dan Gohman
89b2635c5c Remove a redundant assert.
llvm-svn: 82907
2009-09-27 17:48:37 +00:00
Dan Gohman
3248b82ffc Add dominates and releaseMemory member functions to PostDominatorTree.
llvm-svn: 82904
2009-09-27 17:39:12 +00:00
Dan Gohman
473ca67150 Clarify a comment.
llvm-svn: 82902
2009-09-27 15:41:19 +00:00
Dan Gohman
b84f5a3421 Add a properlyDominates member function to ScalarEvolution.
llvm-svn: 82898
2009-09-27 15:26:03 +00:00
Nick Lewycky
d21c325f09 Instruction::clone does not need to take an LLVMContext&. Remove that and
update all the callers.

llvm-svn: 82889
2009-09-27 07:38:41 +00:00
Chris Lattner
b47463f436 remove support for "NoSub" from regex. It seems like a minor optimization
and makes the API more annoying.  Add a Regex::getNumMatches() method.

llvm-svn: 82877
2009-09-26 21:27:04 +00:00
Duncan Sands
ec5d64fdd5 For the NSWSub support in the builder to actually be useable,
there need to be corresponding changes to the constant folders,
done in this patch.

llvm-svn: 82862
2009-09-26 15:35:35 +00:00
Duncan Sands
64511993cb Add methods for creating NSW subtraction, as already exists
for addition.

llvm-svn: 82860
2009-09-26 15:21:48 +00:00
Dan Gohman
2351c2f8b7 Add a comment describing natural loops.
llvm-svn: 82859
2009-09-26 15:09:53 +00:00
Dan Gohman
d585364b0b Rename ConstantFP's getInf to getInfinity.
llvm-svn: 82823
2009-09-25 23:40:21 +00:00
Dan Gohman
ba2b2eb3fe Move MachineMemOperand::getAlignment out of line, to avoid needing
MathExtras.h in MachineMemOperand.h.

llvm-svn: 82822
2009-09-25 23:33:20 +00:00
Dan Gohman
01b2c857ed Add a ConstantFP::getInf utility function for creating infinity ConstantFPs.
llvm-svn: 82818
2009-09-25 23:00:48 +00:00
Jeffrey Yasskin
ae5a12200c Fix a compile failure introduced by r82675 on MinGW which doesn't have
setenv().  This patch just disables the test rather than getting putenv() to
work.  Thanks to Sandeep Patel for reporting the problem.

llvm-svn: 82797
2009-09-25 21:07:20 +00:00
Dan Gohman
0ac693a89e Improve MachineMemOperand handling.
- Allocate MachineMemOperands and MachineMemOperand lists in MachineFunctions.
   This eliminates MachineInstr's std::list member and allows the data to be
   created by isel and live for the remainder of codegen, avoiding a lot of
   copying and unnecessary translation. This also shrinks MemSDNode.
 - Delete MemOperandSDNode. Introduce MachineSDNode which has dedicated
   fields for MachineMemOperands.
 - Change MemSDNode to have a MachineMemOperand member instead of its own
   fields with the same information. This introduces some redundancy, but
   it's more consistent with what MachineInstr will eventually want.
 - Ignore alignment when searching for redundant loads for CSE, but remember
   the greatest alignment.

Target-specific code which previously used MemOperandSDNodes with generic
SDNodes now use MemIntrinsicSDNodes, with opcodes in a designated range
so that the SelectionDAG framework knows that MachineMemOperand information
is available.

llvm-svn: 82794
2009-09-25 20:36:54 +00:00
Dan Gohman
0c4e55a2f8 Rename getTargetNode to getMachineNode, for consistency with the
naming scheme used in SelectionDAG, where there are multiple kinds
of "target" nodes, but "machine" nodes are nodes which represent
a MachineInstr.

llvm-svn: 82790
2009-09-25 18:54:59 +00:00
Victor Hernandez
f772c0b8b2 Revert 82694 "Auto-upgrade malloc instructions to malloc calls." because it causes regressions in the nightly tests.
llvm-svn: 82784
2009-09-25 18:11:52 +00:00
Bob Wilson
94e29af5ac pr4926: ARM requires the stack pointer to be aligned, even for leaf functions.
For the AAPCS ABI, SP must always be 4-byte aligned, and at any "public
interface" it must be 8-byte aligned.  For the older ARM APCS ABI, the stack
alignment is just always 4 bytes.  For X86, we currently align SP at
entry to a function (e.g., to 16 bytes for Darwin), but no stack alignment
is needed at other times, such as for a leaf function.

After discussing this with Dan, I decided to go with the approach of adding
a new "TransientStackAlignment" field to TargetFrameInfo.  This value
specifies the stack alignment that must be maintained even in between calls.
It defaults to 1 except for ARM, where it is 4.  (Some other targets may
also want to set this if they have similar stack requirements. It's not
currently required for PPC because it sets targetHandlesStackFrameRounding
and handles the alignment in target-specific code.) The existing StackAlignment
value specifies the alignment upon entry to a function, which is how we've
been using it anyway.

llvm-svn: 82767
2009-09-25 14:41:49 +00:00
Bob Wilson
841f543880 Update the description of MachineFrameInfo's OffsetAdjustment. The value of
this adjustment does not change the direction or the signs of the object
offsets, and the details of the offset calculations can be target-specific.
Also mention that for most targets this value is only used to generate debug
info.

llvm-svn: 82750
2009-09-25 05:30:55 +00:00
Dan Gohman
5c7946a550 Add a version of dumpr() that has a SelectionDAG* argument.
llvm-svn: 82742
2009-09-25 00:34:34 +00:00
Chris Lattner
af2ce37cb3 add and document regex support for FileCheck. You can now do stuff like:
; CHECK: movl {{%e[a-z][xi]}}, %eax

or whatever.

llvm-svn: 82717
2009-09-24 21:47:32 +00:00
David Goodwin
3ac3dcacc7 Make the end-of-itinerary mark explicit. Some cleanup.
llvm-svn: 82709
2009-09-24 20:22:50 +00:00
Chris Lattner
b1ee14d64b tidy up, fix a memory leak in Regex::isValid
llvm-svn: 82707
2009-09-24 20:15:51 +00:00
Victor Hernandez
ff8027ced6 Auto-upgrade malloc instructions to malloc calls.
Reviewed by Devang Patel.

llvm-svn: 82694
2009-09-24 17:47:49 +00:00
Evan Cheng
f2090008be Clean up LiveVariables and change how it deals with partial updates and kills. This also eliminate the horrible check which scan forward to the end of the basic block. It should be faster and more accurate.
llvm-svn: 82676
2009-09-24 02:15:22 +00:00
Dan Gohman
fc9e3e3cdb Spruce up some comments.
llvm-svn: 82655
2009-09-23 21:06:36 +00:00
Dan Gohman
1256f9265b Rename several variables from EVT to more descriptive names, now that EVT
is also the name of their type, as declarations like "EVT EVT" look
really odd.

llvm-svn: 82654
2009-09-23 21:02:20 +00:00
Dan Gohman
48889db9d9 Add an EVT::getStoreSize function, like getStoreSizeInBits but in bytes.
llvm-svn: 82653
2009-09-23 20:59:10 +00:00
Dan Gohman
2967c534f7 Correct a comment.
llvm-svn: 82648
2009-09-23 20:40:16 +00:00
Devang Patel
18dae0848f Do not leave behind metadata while cloning an instruction.
llvm-svn: 82638
2009-09-23 18:32:25 +00:00
Devang Patel
9253538963 s/*Location/*DebugLocation/g
llvm-svn: 82635
2009-09-23 17:20:43 +00:00
John McCall
24a3aba8b8 Make the type traits for a const pointer defer to those for a unqualified
pointer, instead of providing independent values modelled on the default
implementation.

llvm-svn: 82620
2009-09-23 06:53:51 +00:00
Evan Cheng
863ed2677b Fix PR5024. LiveVariables physical register defs should *commit* only after all
of the defs are processed.
Also fix a implicit_def propagation bug: a implicit_def of a physical register
should be applied to uses of the sub-registers.

llvm-svn: 82616
2009-09-23 06:28:31 +00:00
Dan Gohman
8b2d3ef326 Give MachineMemOperand an operator<<, factoring out code from
two different places for printing MachineMemOperands.

Drop the virtual from Value::dump and instead give Value a
protected virtual hook that can be overridden by subclasses
to implement custom printing. This lets printing be more
consistent, and simplifies printing of PseudoSourceValue
values.

llvm-svn: 82599
2009-09-23 01:33:16 +00:00
Devang Patel
d3d28d0f25 Add SetLocation() to allow IRBuilder user to set location info for an instruction already created.
llvm-svn: 82570
2009-09-22 20:56:31 +00:00
Devang Patel
d785fbf971 Check exisiting dbg MDKind first.
llvm-svn: 82568
2009-09-22 20:54:13 +00:00
Daniel Dunbar
595fbf539a Revert "Don't allow formatted_ostream to be unbuffered, even if its underlying
buffer", while we work out a solution.

Dan convinced me that making debugging annoying for him is worse than 10x being
slower for me. :)

llvm-svn: 82553
2009-09-22 16:33:42 +00:00
Evan Cheng
6e04d960a3 Forgot this.
llvm-svn: 82536
2009-09-22 08:47:59 +00:00
Daniel Dunbar
badca39b69 Revert "Get rid of GetProcessId in Win32/Program.inc.", this breaks
ExecuteAndWait.

llvm-svn: 82522
2009-09-22 04:44:56 +00:00
Daniel Dunbar
ac9a646035 Switch FoldingSet::AddString to StringRef based API.
- This also fixes a dereference of std::string::end, which makes MSVC unhappy and was causing all the static analyzer clang tests to fail.

llvm-svn: 82517
2009-09-22 03:34:53 +00:00
Daniel Dunbar
14c9a4d355 Switch DIDescriptor to use a TrackingVH. - This makes it much safer to work with debug info, since it was extraordinarily easy to have dangling pointers thanks to MDNode uniquing.
llvm-svn: 82507
2009-09-22 02:03:18 +00:00
Daniel Dunbar
6d5513977b Add a TrackingVH value handle.
This is designed for tracking a value even when it might move (like WeakVH), but it is an error to delete the referenced value (unlike WeakVH0. TrackingVH is templated like AssertingVH on the tracked Value subclass, it is an error to RAUW a tracked value to an incompatible type.

For implementation reasons the latter error is only diagnosed on accesses to a mis-RAUWed TrackingVH, because we don't want a virtual interface in a templated class.

The former error is also only diagnosed on access, so that clients are allowed to delete a tracked value, as long as they don't use it. This makes it easier for the client to reason about destruction.

llvm-svn: 82506
2009-09-22 02:02:33 +00:00
Chris Lattner
1ceac42392 move DominatorTree::dominates for instructions out of line,
no functionality change.

llvm-svn: 82490
2009-09-21 22:30:50 +00:00
Dan Gohman
c50bd99a43 Change MachineMemOperand's alignment value to be the alignment of
the base pointer, without the offset. This matches MemSDNode's
new alignment behavior, and holds more interesting information.

llvm-svn: 82473
2009-09-21 19:47:04 +00:00
Chris Lattner
0cd0c5c98f add a helper method.
llvm-svn: 82438
2009-09-21 05:52:45 +00:00
Daniel Dunbar
84e383fc42 Don't allow formatted_ostream to be unbuffered, even if its underlying buffer
is.
 - The problem is that formatted_ostream forces its underlying buffer to be
   unbuffered, so if some client happens to wrap a formatted_ostream around
   something, but still use the underlying stream, then we can end up writing on
   a fully unbuffered output (which was never intended to be unbuffered).

 - This makes clang (and presumably llvm-gcc) -emit-llvm -S a mere 10x faster.

llvm-svn: 82434
2009-09-21 03:56:00 +00:00
Reid Kleckner
cb38af30a0 Implement the JIT side of the GDB JIT debugging interface. To enable this
feature, either build the JIT in debug mode to enable it by default or pass
-jit-emit-debug to lli.

Right now, the only debug information that this communicates to GDB is call
frame information, since it's already being generated to support exceptions in
the JIT.  Eventually, when DWARF generation isn't tied so tightly to AsmPrinter,
it will be easy to push that information to GDB through this interface.

Here's a step-by-step breakdown of how the feature works:

- The JIT generates the machine code and DWARF call frame info
  (.eh_frame/.debug_frame) for a function into memory.
- The JIT copies that info into an in-memory ELF file with a symbol for the
  function.
- The JIT creates a code entry pointing to the ELF buffer and adds it to a
  linked list hanging off of a global descriptor at a special symbol that GDB
  knows about.
- The JIT calls a function marked noinline that GDB knows about and has put an
  internal breakpoint in.
- GDB catches the breakpoint and reads the global descriptor to look for new
  code.
- When sees there is new code, it reads the ELF from the inferior's memory and
  adds it to itself as an object file.
- The JIT continues, and the next time we stop the program, we are able to
  produce a proper backtrace.

Consider running the following program through the JIT:

#include <stdio.h>
void baz(short z) {
  long w = z + 1;
  printf("%d, %x\n", w, *((int*)NULL));  // SEGFAULT here
}
void bar(short y) {
  int z = y + 1;
  baz(z);
}
void foo(char x) {
  short y = x + 1;
  bar(y);
}
int main(int argc, char** argv) {
  char x = 1;
  foo(x);
}

Here is a backtrace before this patch:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x2aaaabdfbd10 (LWP 25476)]
0x00002aaaabe7d1a8 in ?? ()
(gdb) bt
#0  0x00002aaaabe7d1a8 in ?? ()
#1  0x0000000000000003 in ?? ()
#2  0x0000000000000004 in ?? ()
#3  0x00032aaaabe7cfd0 in ?? ()
#4  0x00002aaaabe7d12c in ?? ()
#5  0x00022aaa00000003 in ?? ()
#6  0x00002aaaabe7d0aa in ?? ()
#7  0x01000002abe7cff0 in ?? ()
#8  0x00002aaaabe7d02c in ?? ()
#9  0x0100000000000001 in ?? ()
#10 0x00000000014388e0 in ?? ()
#11 0x00007fff00000001 in ?? ()
#12 0x0000000000b870a2 in llvm::JIT::runFunction (this=0x1405b70,
F=0x14024e0, ArgValues=@0x7fffffffe050)
   at /home/rnk/llvm-gdb/lib/ExecutionEngine/JIT/JIT.cpp:395
#13 0x0000000000baa4c5 in llvm::ExecutionEngine::runFunctionAsMain
(this=0x1405b70, Fn=0x14024e0, argv=@0x13f06f8, envp=0x7fffffffe3b0)
   at /home/rnk/llvm-gdb/lib/ExecutionEngine/ExecutionEngine.cpp:377
#14 0x00000000007ebd52 in main (argc=2, argv=0x7fffffffe398,
envp=0x7fffffffe3b0) at /home/rnk/llvm-gdb/tools/lli/lli.cpp:208

And a backtrace after this patch:
Program received signal SIGSEGV, Segmentation fault.
0x00002aaaabe7d1a8 in baz ()
(gdb) bt
#0  0x00002aaaabe7d1a8 in baz ()
#1  0x00002aaaabe7d12c in bar ()
#2  0x00002aaaabe7d0aa in foo ()
#3  0x00002aaaabe7d02c in main ()
#4  0x0000000000b870a2 in llvm::JIT::runFunction (this=0x1405b70,
F=0x14024e0, ArgValues=...)
   at /home/rnk/llvm-gdb/lib/ExecutionEngine/JIT/JIT.cpp:395
#5  0x0000000000baa4c5 in llvm::ExecutionEngine::runFunctionAsMain
(this=0x1405b70, Fn=0x14024e0, argv=..., envp=0x7fffffffe3c0)
   at /home/rnk/llvm-gdb/lib/ExecutionEngine/ExecutionEngine.cpp:377
#6  0x00000000007ebd52 in main (argc=2, argv=0x7fffffffe3a8,
envp=0x7fffffffe3c0) at /home/rnk/llvm-gdb/tools/lli/lli.cpp:208

llvm-svn: 82418
2009-09-20 23:52:43 +00:00