the processor keeps a return addresses stack (RAS) which stores the address
and the instruction execution state of the instruction after a function-call
type branch instruction.
Calling a "noreturn" function with normal call instructions (e.g. bl) can
corrupt RAS and causes 100% return misprediction so LLVM should use a
unconditional branch instead. i.e.
mov lr, pc
b _foo
The "mov lr, pc" is issued in order to get proper backtrace.
rdar://8979299
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undefined result. This adds new ISD nodes for the new semantics,
selecting them when the LLVM intrinsic indicates that the undef behavior
is desired. The new nodes expand trivially to the old nodes, so targets
don't actually need to do anything to support these new nodes besides
indicating that they should be expanded. I've done this for all the
operand types that I could figure out for all the targets. Owners of
various targets, please review and let me know if any of these are
incorrect.
Note that the expand behavior is *conservatively correct*, and exactly
matches LLVM's current behavior with these operations. Ideally this
patch will not change behavior in any way. For example the regtest suite
finds the exact same instruction sequences coming out of the code
generator. That's why there are no new tests here -- all of this is
being exercised by the existing test suite.
Thanks to Duncan Sands for reviewing the various bits of this patch and
helping me get the wrinkles ironed out with expanding for each target.
Also thanks to Chris for clarifying through all the discussions that
this is indeed the approach he was looking for. That said, there are
likely still rough spots. Further review much appreciated.
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When this field is true it means that the load is from constant (runt-time or compile-time) and so can be hoisted from loops or moved around other memory accesses
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with a vector condition); such selects become VSELECT codegen nodes.
This patch also removes VSETCC codegen nodes, unifying them with SETCC
nodes (codegen was actually often using SETCC for vector SETCC already).
This ensures that various DAG combiner optimizations kick in for vector
comparisons. Passes dragonegg bootstrap with no testsuite regressions
(nightly testsuite as well as "make check-all"). Patch mostly by
Nadav Rotem.
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these was just one line of a file. Explicitly set the eol-style property on the
files to try and ensure this fix stays.
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In other words, do not keep track of argument's location. The debugger (gdb) is not prepared to see line table entries for arguments. For the debugger, "second" line table entry marks beginning of function body.
This requires some coordination with debugger to get this working.
- The debugger needs to be aware of prolog_end attribute attached with line table entries.
- The compiler needs to accurately mark prolog_end in line table entries (at -O0 and at -O1+)
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and "save_volatiles" correctly. This completes the custom calling convention
functionality changes for the MBlaze backend that were started in 121888.
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2. Make sure that the MBlaze stack is aligned to 4-byte boundaries.
3. Determine frame indexes that should be placed in the callers stack frame, as per the MBlaze ABI, and place them in the correct locations.
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and as such can be represented by an MVT - the more complicated
EVT is not needed. Use MVT for ValVT everywhere.
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value type, so there is no point in passing it around using
an EVT. Use the simpler MVT everywhere. Rather than trying
to propagate this information maximally in all the code that
using the calling convention stuff, I chose to do a mainly
low impact change instead.
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mostly based on the ARM AsmParser at this time and is not particularly
functional.
Changed the MBlaze data layout from:
"E-p:32:32-i8:8:8-i16:16:16-i64:32:32-f64:32:32-v64:32:32-v128:32:32-n32"
to:
"E-p:32:32:32-i8:8:8-i16:16:16"
because the MicroBlaze doesn't have i64, f64, v64, or v128 data types.
Cleaned up the MBlaze source code:
1. The floating point register class has been removed. The
MicroBlaze does not have floating point registers. Floating
point values are simply stored in integer registers.
2. Renaming the CPURegs register class to GPR to reflect the
standard naming.
3. Removing a lot of stale code from AsmPrinter after
the conversion to InstPrinter.
4. Simplified sign extended loads by marking them as
expanded in ISelLowering.
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1. A delay slot filler that searches for valid instructions
to fill the delay slot with. Previously NOPs would always
be inserted into delay slots.
2. Support for MC based instruction printer added.
3. Support for MC based machine code generation and ELF
file generation. ELF file generation does not yet
completely work as much of the ELF support infrastructure
is still x86/x86-64 specific.
4. General clean up of the MBlaze backend code. Much of the
tablegen code has been cleanup and simplified.
Bug Fixes:
1. Removed duplicate periods from subtarget feature descriptions.
2. Many of the instructions had bad machine code information
in the tablegen files. Much of this has been fixed.
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const_casts, and it reinforces the design of the Target classes being
immutable.
SelectionDAGISel::IsLegalToFold is now a static member function, because
PIC16 uses it in an unconventional way. There is more room for API
cleanup here.
And PIC16's AsmPrinter no longer uses TargetLowering.
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