libgcc sets the stack limit field in TCB to 256 bytes above the actual
allocated stack limit. This means if the function's stack frame needs
less than 256 bytes, we can just compare the stack pointer with the
stack limit. This should result in lesser calls to __morestack.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145766 91177308-0d34-0410-b5e6-96231b3b80d8
Currently LLVM pads the call to __morestack with a add and sub of 8
bytes to esp. This isn't correct since __morestack expects the call
to be followed directly by a ret.
This commit also adjusts the relevant test-case.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145765 91177308-0d34-0410-b5e6-96231b3b80d8
change, now you need a TargetOptions object to create a TargetMachine. Clang
patch to follow.
One small functionality change in PTX. PTX had commented out the machine
verifier parts in their copy of printAndVerify. That now calls the version in
LLVMTargetMachine. Users of PTX who need verification disabled should rely on
not passing the command-line flag to enable it.
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MORESTACK_RET_RESTORE_R10; which are lowered to a RET and a RET
followed by a MOV respectively. Having a fake instruction prevents
the verifier from seeing a MachineBasicBlock end with a
non-terminator (MOV). It also prevents the rather eccentric case of a
MachineBasicBlock ending with RET but having successors nevertheless.
Patch by Sanjoy Das.
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release the stack segment and reset the stack pointer. Place the code in its own
MBB to make the verifier happy.
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X86. Modify the pass added in the previous patch to call this new
code.
This new prologues generated will call a libgcc routine (__morestack)
to allocate more stack space from the heap when required
Patch by Sanjoy Das.
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unwind encoding for that function. This simply crawls through the prolog looking
for machine instrs marked as "frame setup". It can calculate from these what the
compact unwind should look like.
This is currently disabled because of needed linker support. But initial tests
look good.
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assert when the frame pointer is -1 (i.e., the function is "frameless").
Still to do: "frameless" unwind information.
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functionality change.
Later on, we'll use the flag to emit SEH pseudo-ops that describe how the
call frame was built.
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LTO friendly as we can now correctly merge files compiled with or without
-fasynchronous-unwind-tables.
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Change ELF systems to use CFI for producing the EH tables. This reduces the
size of the clang binary in Debug builds from 690MB to 679MB.
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It improves Win64's prologue/epilogue but it would not affect ia32 and amd64 (lack of nonvolatile XMMs).
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