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Commit Graph

353 Commits

Author SHA1 Message Date
Francis Visoiu Mistrih
ce6a8314c3 [DebugInfo][X86] Add start-after flags to MIR tests
These tests would fail with -verify-machineinstrs because the MI
generated from the IR would be merged with the one already in the MIR
files, and we get the following error:

```
*** Bad machine code: Function has NoVRegs property but there are VReg operands ***
- function:    f
```

Differential Revision: https://reviews.llvm.org/D49191

llvm-svn: 336907
2018-07-12 14:36:48 +00:00
Mikael Holmen
96b4fab48a [DebugInfo] Make sure all DBG_VALUEs' reguse operands have IsDebug property
Summary:
In some cases, these operands lacked the IsDebug property, which is meant to signal that
they should not affect codegen. This patch adds a check for this property in the
MachineVerifier and adds it where it was missing.

This includes refactorings to use MachineInstrBuilder construction functions instead of
manually setting up the intrinsic everywhere.

Patch by: JesperAntonsson

Reviewers: aprantl, rnk, echristo, javed.absar

Reviewed By: aprantl

Subscribers: qcolombet, sdardis, nemanjai, JDevlieghere, atanasyan, llvm-commits

Differential Revision: https://reviews.llvm.org/D48319

llvm-svn: 335214
2018-06-21 10:03:34 +00:00
Matt Davis
2054afa728 [MIRParser] Update a diagnostic message to use the correct register sigil. NFC
Summary:
Patch r323922 changed the sigil for physical registers to '$',  instead of '%'.
An error message was missed during this change, and reports the wrong sigil.
This patch corrects that diagnostic and the tests that check that error string.


Reviewers: zer0, bjope

Reviewed By: bjope

Subscribers: bjope, thegameg, plotfi, llvm-commits

Differential Revision: https://reviews.llvm.org/D48086

llvm-svn: 335066
2018-06-19 18:39:40 +00:00
Amara Emerson
f60ecfcfa7 [MIRParser] Add parser support for 'true' and 'false' i1s.
We already output true and false in the printer, but the parser isn't able to
read it.

Differential Revision: https://reviews.llvm.org/D47424

llvm-svn: 333970
2018-06-05 00:17:13 +00:00
Puyan Lotfi
497c6e7bcc [NFC] MIR-Canon: switching to a stable string sorting of instructions.
llvm-svn: 332191
2018-05-13 06:07:20 +00:00
Shiva Chen
a2029fa58e [DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label.
In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is

!DILabel(scope: !1, name: "foo", file: !2, line: 3)

We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is

llvm.dbg.label(metadata !1)

It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.

We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.

Differential Revision: https://reviews.llvm.org/D45024

Patch by Hsiangkai Wang.

llvm-svn: 331841
2018-05-09 02:40:45 +00:00
Roman Tereshin
de9f27a4ff [MIRParser][GlobalISel] Parsing vector pointer types (<M x pA>)
MIParser wasn't able to parse LLTs like `<4 x p0>`, fixing that.

Reviewers: qcolombet t.p.northover aditya_nandakumar

Reviewed By: qcolombet

Subscribers: rovka, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D46490

llvm-svn: 331712
2018-05-08 02:02:50 +00:00
Heejin Ahn
6353a444b6 [MIRPraser] Improve error checking for typed immediate operands
Summary:
This improves error checks for typed immediate operands introduced in
D45948 (rL331586), and removes a code block copied by mistake.

Reviewers: rtereshin

Subscribers: dschuff, sbc100, jgravelle-google, llvm-commits

Differential Revision: https://reviews.llvm.org/D46491

llvm-svn: 331600
2018-05-05 20:53:23 +00:00
Heejin Ahn
8b835c4634 [MIRParser] Allow register class names in the form of integer/scalar
Summary:
The current code cannot handle register class names like 'i32', which is
a valid register class name in WebAssembly. This patch removes special
handling for integer/scalar/pointer type parsing and treats them as
normal identifiers.

Reviewers: thegameg

Subscribers: jfb, dschuff, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D45948

llvm-svn: 331586
2018-05-05 07:05:51 +00:00
Michael Berg
dc3d19e5de MachineInst support mapping SDNode fast math flags for support in Back End code generation
Summary:
Machine Instruction flags for fast math support and MIR print support


Reviewers: spatel, arsenm

Reviewed By: arsenm

Subscribers: wdng

Differential Revision: https://reviews.llvm.org/D45781

llvm-svn: 331417
2018-05-03 00:07:56 +00:00
Roman Tereshin
2a5c2d1d3e [MIR] Reset unique MBB numbering in MachineFunction::reset()
No need to waste space nor number MBBs differently if MF gets recreated.

Reviewers: qcolombet, stoklund, t.p.northover, bogner, javed.absar

Reviewed By: qcolombet

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46078

llvm-svn: 331213
2018-04-30 18:58:57 +00:00
Francis Visoiu Mistrih
73884955f2 [MIR] Add support for debug metadata for fixed stack objects
Debug var, expr and loc were only supported for non-fixed stack objects.

This patch adds the following fields to the "fixedStack:" entries, and
renames the ones from "stack:" to:

* debug-info-variable
* debug-info-expression
* debug-info-location

Differential Revision: https://reviews.llvm.org/D46032

llvm-svn: 330859
2018-04-25 18:58:06 +00:00
Krzysztof Parzyszek
785430b011 [if-converter] Handle BBs that terminate in ret during diamond conversion
This fixes https://llvm.org/PR36825.

Original patch by Valentin Churavy (D45218).

Differential Revision: https://reviews.llvm.org/D45731

llvm-svn: 330345
2018-04-19 17:26:46 +00:00
Puyan Lotfi
52a5229366 [MIR-Canon] Fixing a test failure caused by COPY Folding.
llvm-svn: 330115
2018-04-16 09:31:49 +00:00
Puyan Lotfi
b93eb7f63b [MIR-Canon] Adding ISA-Agnostic COPY Folding.
Transforms the following:

    %vreg1234:gpr32 = COPY %42
    %vreg1235:gpr32 = COPY %vreg1234
    %vreg1236:gpr32 = COPY %vreg1235
    $w0 = COPY %vreg1236

into:

    $w0 = COPY %42

Assuming %42 is also a gpr32

llvm-svn: 330113
2018-04-16 09:03:03 +00:00
Puyan Lotfi
cd9bfe0331 Attempting to work around a non-determinism issue.
The main thing that matters with this test is that the COPYs
are moved together not where the REG_SEQUENCES are.

llvm-svn: 329850
2018-04-11 20:29:32 +00:00
Francis Visoiu Mistrih
0ba2468ada [MIR] Add support for MachineFrameInfo::LocalFrameSize
MFI.LocalFrameSize was not serialized.

It is usually set from LocalStackSlotAllocation, so if that pass doesn't
run it is impossible do deduce it from the stack objects. Until now, this
information was lost.

llvm-svn: 329382
2018-04-06 08:56:25 +00:00
Puyan Lotfi
8549095eb0 [MIR-Canon] Improving performance by switching to named vregs.
No more skipping thounsands of vregs. Much faster running time.

llvm-svn: 329246
2018-04-05 00:27:15 +00:00
Puyan Lotfi
602a87e552 [MIR-Canon] Adding support for multi-def -> user distance reduction.
llvm-svn: 329243
2018-04-05 00:08:15 +00:00
Puyan Lotfi
b93beb070b [MIR-Canon] Adding support for local idempotent instruction hoisting.
llvm-svn: 328915
2018-03-31 05:48:51 +00:00
Puyan Lotfi
262cfa2993 [MIR] Adding support for Named Virtual Registers in MIR.
llvm-svn: 328887
2018-03-30 18:15:54 +00:00
Francis Visoiu Mistrih
391493fd6e [MIR] Allow frame-setup and frame-destroy on the same instruction
Nothing prevents us from having both frame-setup and frame-destroy on
the same instruction.

When merging:
* frame-setup OPCODE1
* frame-destroy OPCODE2
into
* frame-setup frame-destroy OPCODE3

we want to be able to print and parse both flags.

llvm-svn: 327442
2018-03-13 19:53:16 +00:00
Roman Tereshin
dd2bafca46 [MIRParser] Accept overloaded intrinsic names w/o type suffixes
Function::lookupIntrinsicID is somewhat forgiving as it comes to
overloaded intrinsics' names: it returns an ID as soon as the name
provided has a prefix that matches a registered intrinsic's name w/o
actually checking that the rest of the name encodes all the concrete arg
types, let alone that those types are compatible with the intrinsic's
definition.

That's probably fine and comes in handy in MIR serialization: we don't
care about IR types at MIR level and every intrinsic should be
selectable based on its ID and low-level types (LLTs) of its operands,
including the overloaded ones, so there is no point in serializing
mangled IR types as part of the intrinsic's name.

However, lookupIntrinsicID is somewhat inconsistent in its forgiveness:
if the name provided is actually an exact match, it will refuse to
return the ID if the intrinsic is overloaded. There is probably no
real reason for that and it renders MIRParser incapable to deserialize
MIR MIRPrinter serialized.

This commit fixes it.

Reviewers: rnk, aditya_nandakumar, qcolombet, thegameg, dsanders,
marcello.maggioni

Reviewed By: bogner

Subscribers: javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D43267

llvm-svn: 326387
2018-02-28 23:51:49 +00:00
Roman Tereshin
fbc0eeef58 [GlobalISel] Print/Parse FailedISel MachineFunction property
FailedISel MachineFunction property is part of the CodeGen pipeline
state as much as every other property, notably, Legalized,
RegBankSelected, and Selected. Let's make that part of the state also
serializable / de-serializable, so if GlobalISel aborts on some of the
functions of a large module, but not the others, it could be easily seen
and the state of the pipeline could be maintained through llc's
invocations with -stop-after / -start-after.

To make MIR printable and generally to not to break it too much too
soon, this patch also defers cleaning up the vreg -> LLT map until
ResetMachineFunctionPass.

To make MIR with FailedISel: true also machine verifiable, machine
verifier is changed so it treats a MIR-module as non-regbankselected and
non-selected if there is FailedISel property set.

Reviewers: qcolombet, ab

Reviewed By: dsanders

Subscribers: javed.absar, rovka, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D42877

llvm-svn: 326343
2018-02-28 17:55:45 +00:00
Aditya Nandakumar
dbed654493 [GISel]: Verify COPIES involving generic registers.
Add verification for copies involving generic registers if they are
compatible - ie if it is a generic copy, then the types are the
same, and if a COPY b/w generic and target virtual register, then
the sizes should be the same. Only checks if there are no sub registers
involved for now.

https://reviews.llvm.org/D37775

llvm-svn: 324696
2018-02-09 01:27:23 +00:00
Puyan Lotfi
d4c615be8c Followup on Proposal to move MIR physical register namespace to '$' sigil.
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
2018-01-31 22:04:26 +00:00
Justin Bogner
34e32c59b8 Add triples or specify REQUIRES: default_triple to some tests
These were all failing when building the X86 backend but specifying
LLVM_DEFAULT_TARGET_TRIPLE=''.

llvm-svn: 323608
2018-01-27 23:31:09 +00:00
Francis Visoiu Mistrih
86146e9507 [MIR] Add support for addrspace in MIR
Add support for printing / parsing the addrspace of a MachineMemOperand.

Fixes PR35970.

Differential Revision: https://reviews.llvm.org/D42502

llvm-svn: 323521
2018-01-26 11:47:28 +00:00
Alexander Ivchenko
3d134da6a7 [x86] Mostly reautogenerate a bunch of tests that affect D37775. NFC
Tests required minor manual tweaks:
CodeGen/MIR/X86/generic-instr-type.mir
CodeGen/X86/GlobalISel/select-copy.mir
CodeGen/X86/GlobalISel/select-ext.mir
CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir
CodeGen/X86/GlobalISel/select-phi.mir
CodeGen/X86/GlobalISel/select-trunc.mir
CodeGen/X86/GlobalISel/select-frameIndex.mir

And following tests are split into 32/64 versions:
CodeGen/X86/GlobalISel/legalize-GV.mir
CodeGen/X86/GlobalISel/select-frameIndex.mir

llvm-svn: 323209
2018-01-23 15:48:50 +00:00
Matthias Braun
8661ea0103 Move tests to the correct place
test/CodeGen/MIR is for testing the MIR parser/printer. Tests for passes
and targets belong to test/CodeGen/TARGETNAME.

llvm-svn: 322925
2018-01-19 06:08:15 +00:00
Puyan Lotfi
bb3ea20b55 [MIR] Repurposing '$' sigil used by external symbols. Replacing with '&'.
Planning to add support for named vregs. This puts is in a conundrum since
physregs are named as well. To rectify this we need to use a sigil other than
'%' for physregs in MIR. We've settled on using '$' for physregs but first we
must repurpose it from external symbols using it, which is what this commit is
all about. We think '&' will have familiar semantics for C/C++ users.

llvm-svn: 322146
2018-01-10 00:56:48 +00:00
Francis Visoiu Mistrih
af104b58a6 [MIR] Add support for the frame-destroy MachineInstr flag
We are printing / parsing the `frame-setup` MachineInstr flag but not
the `frame-destroy` one.

Differential Revision: https://reviews.llvm.org/D41509

llvm-svn: 322071
2018-01-09 11:33:22 +00:00
Francis Visoiu Mistrih
061acf9c7f [YAML] Add support for non-printable characters
LLVM IR function names which disable mangling start with '\01'
(https://www.llvm.org/docs/LangRef.html#identifiers).

When an identifier like "\01@abc@" gets dumped to MIR, it is quoted, but
only with single quotes.

http://www.yaml.org/spec/1.2/spec.html#id2770814:

"The allowed character range explicitly excludes the C0 control block
allowed), the surrogate block #xD800-#xDFFF, #xFFFE, and #xFFFF."

http://www.yaml.org/spec/1.2/spec.html#id2776092:

"All non-printable characters must be escaped.
[...]
Note that escape sequences are only interpreted in double-quoted scalars."

This patch adds support for printing escaped non-printable characters
between double quotes if needed.

Should also fix PR31743.

Differential Revision: https://reviews.llvm.org/D41290

llvm-svn: 320996
2017-12-18 17:38:03 +00:00
Francis Visoiu Mistrih
bd3f69f6b1 [MIR] Add support for missing CFI directives
The following CFI directives are suported by MC but not by MIR:

* .cfi_rel_offset
* .cfi_adjust_cfa_offset
* .cfi_escape
* .cfi_remember_state
* .cfi_restore_state
* .cfi_undefined
* .cfi_register
* .cfi_window_save

Add support for printing, parsing and update tests.

Differential Revision: https://reviews.llvm.org/D41230

llvm-svn: 320819
2017-12-15 15:17:18 +00:00
Adrian Prantl
198732da57 Ignore metainstructions during the shrink wrap analysis
Shrink wrapping should ignore DBG_VALUEs referring to frame indices,
since the presence of debug information must not affect code
generation.

Differential Revision: https://reviews.llvm.org/D41187

llvm-svn: 320606
2017-12-13 19:10:54 +00:00
Geoff Berry
cb61a9aa52 [MachineOperand][MIR] Add isRenamable to MachineOperand.
Summary:
Add isRenamable() predicate to MachineOperand.  This predicate can be
used by machine passes after register allocation to determine whether it
is safe to rename a given register operand.  Register operands that
aren't marked as renamable may be required to be assigned their current
register to satisfy constraints that are not captured by the machine
IR (e.g. ABI or ISA constraints).

Reviewers: qcolombet, MatzeB, hfinkel

Subscribers: nemanjai, mcrosier, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D39400

llvm-svn: 320503
2017-12-12 17:53:59 +00:00
Mikael Holmen
e9464f0f47 Skip DBG instr in OptimizePHIs when looking for dead PHI cycles
Summary:
Changed use_instructions() to use_nodbg_instructions() when
building an instruction set.

We don't want the presence of debug info to affect the code
we generate.

Reviewers: dblaikie, Eugene.Zelenko, chandlerc, aprantl

Reviewed By: aprantl

Subscribers: aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D40882

llvm-svn: 320010
2017-12-07 07:01:21 +00:00
Francis Visoiu Mistrih
30264d4391 [CodeGen] Unify MBB reference format in both MIR and debug output
As part of the unification of the debug format and the MIR format, print
MBB references as '%bb.5'.

The MIR printer prints the IR name of a MBB only for block definitions.

* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)->getNumber\(\)/" << printMBBReference(*\1)/g'
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)\.getNumber\(\)/" << printMBBReference(\1)/g'
* find . \( -name "*.txt" -o -name "*.s" -o -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#([0-9]+)/%bb.\1/g'
* grep -nr 'BB#' and fix

Differential Revision: https://reviews.llvm.org/D40422

llvm-svn: 319665
2017-12-04 17:18:51 +00:00
Francis Visoiu Mistrih
cd4ff3e8fc [CodeGen] Always use printReg to print registers in both MIR and debug
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
2017-11-30 16:12:24 +00:00
Francis Visoiu Mistrih
86edc13433 [CodeGen] Print "%vreg0" as "%0" in both MIR and debug output
As part of the unification of the debug format and the MIR format, avoid
printing "vreg" for virtual registers (which is one of the current MIR
possibilities).

Basically:

* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E "s/%vreg([0-9]+)/%\1/g"
* grep -nr '%vreg' . and fix if needed
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E "s/ vreg([0-9]+)/ %\1/g"
* grep -nr 'vreg[0-9]\+' . and fix if needed

Differential Revision: https://reviews.llvm.org/D40420

llvm-svn: 319427
2017-11-30 12:12:19 +00:00
Daniel Sanders
17578579a6 [mir] Print/Parse both MOLoad and MOStore when they occur together.
Summary:
They're not always mutually exclusive. read-modify-write atomics are both
at the same time. One example of this is the SWP instructions on AArch64.
Another example is GlobalISel's G_ATOMICRMW_* generic instructions which
will be added in a later patch.

Reviewers: arphaman, aemerson

Reviewed By: aemerson

Subscribers: aemerson, javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D40157

llvm-svn: 319202
2017-11-28 18:57:02 +00:00
Oren Ben Simhon
78031089be Control-Flow Enforcement Technology - Shadow Stack support (LLVM side)
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
2017-11-26 13:02:45 +00:00
Bjorn Pettersson
491c957c8a [MIRPrinter] Use %subreg.xxx syntax for subregister index operands
Summary:
Print %subreg.<subregidxname> instead of just the subregister
index when printing immediate operands corresponding to subreg
indices in INSERT_SUBREG, EXTRACT_SUBREG, SUBREG_TO_REG and
REG_SEQUENCE.

Reviewers: qcolombet, MatzeB

Reviewed By: MatzeB

Subscribers: nhaehnle, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D39696

llvm-svn: 317513
2017-11-06 21:46:06 +00:00
Francis Visoiu Mistrih
94c00d2e59 [AsmPrinterDwarf] Add support for .cfi_restore directive
As of today we only use .cfi_offset to specify the offset of a CSR, but
we never use .cfi_restore when the CSR is restored.

If we want to perform a more advanced type of shrink-wrapping, we need
to use .cfi_restore in order to switch the CFI state between blocks.

This patch only aims at adding support for the directive.

Differential Revision: https://reviews.llvm.org/D36114

llvm-svn: 317199
2017-11-02 12:00:58 +00:00
Justin Bogner
d5cead992a MIR: Print the register class or bank in vreg defs
This updates the MIRPrinter to include the regclass when printing
virtual register defs, which is already valid syntax for the
parser. That is, given 64 bit %0 and %1 in a "gpr" regbank,

  %1(s64) = COPY %0(s64)

would now be written as

  %1:gpr(s64) = COPY %0(s64)

While this change alone introduces a bit of redundancy with the
registers block, it allows us to update the tests to be more concise
and understandable and brings us closer to being able to remove the
registers block completely.

Note: We generally only print the class in defs, but there is one
exception. If there are uses without any defs whatsoever, we'll print
the class on all uses. I'm not completely convinced this comes up in
meaningful machine IR, but for now the MIRParser and MachineVerifier
both accept that kind of stuff, so we don't want to have a situation
where we can print something we can't parse.

llvm-svn: 316479
2017-10-24 18:04:54 +00:00
Justin Bogner
1f13e1115b Canonicalize a large number of mir tests using update_mir_test_checks
This converts a large and somewhat arbitrary set of tests to use
update_mir_test_checks. I ran the script on all of the tests I expect
to need to modify for an upcoming mir syntax change and kept the ones
that obviously didn't change the tests in ways that might make it
harder to understand.

llvm-svn: 316137
2017-10-18 23:18:12 +00:00
Mikael Holmen
bc25b9378a [RegisterCoalescer] Don't set read-undef in pruneValues, only clear
Summary:
The comments in the code said

 // Remove <def,read-undef> flags. This def is now a partial redef.

but the code didn't just remove read-undef, it could introduce new ones which
could cause errors.

E.g. if we have something like

%vreg1<def> = IMPLICIT_DEF
%vreg2:subreg1<def, read-undef> = op %vreg3, %vreg4
%vreg2:subreg2<def> = op %vreg6, %vreg7

and we merge %vreg1 and %vreg2 then we should not set undef on the second subreg
def, which the old code did.

Now we solve this by actually do what the code comment says. We remove
read-undef flags rather than remove or introduce them.

Reviewers: qcolombet, MatzeB

Reviewed By: MatzeB

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38616

llvm-svn: 315564
2017-10-12 06:21:28 +00:00
Mikael Holmen
30fae2f44d Recommit [UnreachableBlockElim] Use COPY if PHI input is undef
This time invoking llc with "-march=x86-64" in the testcase, so we don't assume
the default target is x86.

Summary:
If we have

    %vreg0<def> = PHI %vreg2<undef>, <BB#0>, %vreg3, <BB#2>; GR32:%vreg0,%vreg2,%vreg3
    %vreg3<def,tied1> = ADD32ri8 %vreg0<kill,tied0>, 1, %EFLAGS<imp-def>; GR32:%vreg3,%vreg0

then we can't just change %vreg0 into %vreg3, since %vreg2 is actually
undef. We would have to also copy the undef flag to be able to change the
register.

Instead we deal with this case like other cases where we can't just
replace the register: we insert a COPY. The code creating the COPY already
copied all flags from the PHI input, so the undef flag will be transferred
as it should.

Reviewers: kparzysz

Reviewed By: kparzysz

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38235

llvm-svn: 314882
2017-10-04 07:42:45 +00:00
Mikael Holmen
29c5a8da49 Revert r314879 "[UnreachableBlockElim] Use COPY if PHI input is undef"
Build-bots broke on the new testcase. I'll investigate and fix.

llvm-svn: 314880
2017-10-04 06:39:22 +00:00
Mikael Holmen
3a82bf8c1f [UnreachableBlockElim] Use COPY if PHI input is undef
Summary:
If we have

    %vreg0<def> = PHI %vreg2<undef>, <BB#0>, %vreg3, <BB#2>; GR32:%vreg0,%vreg2,%vreg3
    %vreg3<def,tied1> = ADD32ri8 %vreg0<kill,tied0>, 1, %EFLAGS<imp-def>; GR32:%vreg3,%vreg0

then we can't just change %vreg0 into %vreg3, since %vreg2 is actually
undef. We would have to also copy the undef flag to be able to change the
register.

Instead we deal with this case like other cases where we can't just
replace the register: we insert a COPY. The code creating the COPY already
copied all flags from the PHI input, so the undef flag will be transferred
as it should.

Reviewers: kparzysz

Reviewed By: kparzysz

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D38235

llvm-svn: 314879
2017-10-04 06:06:31 +00:00