This cleans up a number of operations that only claimed te use EFLAGS
due to using DF. But no instructions which we think of us setting EFLAGS
actually modify DF (other than things like popf) and so this needlessly
creates uses of EFLAGS that aren't really there.
In fact, DF is so restrictive it is pretty easy to model. Only STD, CLD,
and the whole-flags writes (WRFLAGS and POPF) need to model this.
I've also somewhat cleaned up some of the flag management instruction
definitions to be in the correct .td file.
Adding this extra register also uncovered a failure to use the correct
datatype to hold X86 registers, and I've corrected that as necessary
here.
Differential Revision: https://reviews.llvm.org/D45154
llvm-svn: 329673
Registers E[A-D]X, E[SD]I, E[BS]P, and EIP have 16-bit subregisters
that cover the low halves of these registers. This change adds artificial
subregisters for the high halves in order to differentiate (in terms of
register units) between the 32- and the low 16-bit registers.
This patch contains parts that aim to preserve the calculated register
pressure. This is in order to preserve the current codegen (minimize the
impact of this patch). The approach of having artificial subregisters
could be used to fix PR23423, but the pressure calculation would need
to be changed.
Differential Revision: https://reviews.llvm.org/D43353
llvm-svn: 328016
Discussed here:
http://lists.llvm.org/pipermail/llvm-dev/2018-January/120320.html
In preparation for adding support for named vregs we are changing the sigil for
physical registers in MIR to '$' from '%'. This will prevent name clashes of
named physical register with named vregs.
llvm-svn: 323922
output
As part of the unification of the debug format and the MIR format,
always use `printReg` to print all kinds of registers.
Updated the tests using '_' instead of '%noreg' until we decide which
one we want to be the default one.
Differential Revision: https://reviews.llvm.org/D40421
llvm-svn: 319445
Shadow stack solution introduces a new stack for return addresses only.
The HW has a Shadow Stack Pointer (SSP) that points to the next return address.
If we return to a different address, an exception is triggered.
The shadow stack is managed using a series of intrinsics that are introduced in this patch as well as the new register (SSP).
The intrinsics are mapped to new instruction set that implements CET mechanism.
The patch also includes initial infrastructure support for IBT.
For more information, please see the following:
https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf
Differential Revision: https://reviews.llvm.org/D40223
Change-Id: I4daa1f27e88176be79a4ac3b4cd26a459e88fed4
llvm-svn: 318996
I am leaving the code in clang which filters mxcsr from the clobber list because that is still technically correct and will be useful again when the MXCSR register is reintroduced.
llvm-svn: 297664
This adds MXCSR to the set of recognized registers for X86 targets and updates the instructions that read or write it. I do not intend for all of the various floating point instructions that implicitly use the control bits or update the status bits of this register to ever have that usage modeled by default. However, when constrained floating point modes (such as strict FP exception status modeling or dynamic rounding modes) are enabled, implicit use/def information for MXCSR will be added to those instructions.
Until those additional updates are made this should cause (almost?) no functional changes. Theoretically, this will prevent instructions like LDMXCSR and STMXCSR from being moved past one another, but that should be prevented anyway and I haven't found a case where it is happening now.
Differential Revision: https://reviews.llvm.org/D29903
llvm-svn: 295004
Add an option to enable the analysis of MachineFunction register
usage to extract the list of clobbered registers.
When enabled, the CodeGen order is changed to be bottom up on the Call
Graph.
The analysis is split in two parts, RegUsageInfoCollector is the
MachineFunction Pass that runs post-RA and collect the list of
clobbered registers to produce a register mask.
An immutable pass, RegisterUsageInfo, stores the RegMask produced by
RegUsageInfoCollector, and keep them available. A future tranformation
pass will use this information to update every call-sites after
instruction selection.
Patch by Vivek Pandya <vivekvpandya@gmail.com>
Differential Revision: http://reviews.llvm.org/D20769
llvm-svn: 272403
Chandler Carruth