If an immediate is only used in an AND node, it is possible that the immediate can be more optimally materialized when negated. If this is the case, we can negate the immediate and use a BIC instead;
int i(int a) {
return a & 0xfffffeec;
}
Used to produce:
ldr r1, [CONSTPOOL]
ands r0, r1
CONSTPOOL: 0xfffffeec
And now produces:
movs r1, #255
adds r1, #20 ; Less costly immediate generation
bics r0, r1
llvm-svn: 272251
Add support to the AArch64 IAS for the `.arch` directive. This allows the
assembly input to use architectural functionality in part of a file. This is
used in existing code like BoringSSL.
Resolves PR26016!
llvm-svn: 272241
We can safely rely on a NoWrap add recurrence causing UB down the road
only if we know the loop does not have a exit expressed in a way that is
opaque to ScalarEvolution (e.g. by a function call that conditionally
calls exit(0)).
I believe with this change PR28012 is fixed.
Note: I had to change some llvm-lit tests in LoopReroll, since it looks
like they were depending on this incorrect behavior.
llvm-svn: 272237
Without that check it was possible to write test cases where the size
was not specified and we ended up with weird asserts down the road,
because the default value (1) would not make sense.
llvm-svn: 272226
Summary:
This fixes PR26682. Also add LCSSA as a preserved pass to LoopSimplify,
that looks correct to me and allows to write a test for the issue.
Reviewers: chandlerc, bogner, sanjoy
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D21112
llvm-svn: 272224
Summary:
This fixes PR27617.
Bug description: The SLPVectorizer asserts on encountering GEPs with different index types, such as i8 and i64.
The patch includes a simple relaxation of the assert to allow constants being of different types, along with a regression test that will provoke the unrelaxed assert.
Reviewers: nadav, mzolotukhin
Subscribers: JesperAntonsson, llvm-commits, mzolotukhin
Differential Revision: http://reviews.llvm.org/D20685
Patch by Jesper Antonsson!
llvm-svn: 272206
Summary:
Consider the following diamond CFG:
A
/ \
B C
\/
D
Suppose A->B and A->C have probabilities 81% and 19%. In block-placement, A->B is called a hot edge and the final placement should be ABDC. However, the current implementation outputs ABCD. This is because when choosing the next block of B, it checks if Freq(C->D) > Freq(B->D) * 20%, which is true (if Freq(A) = 100, then Freq(B->D) = 81, Freq(C->D) = 19, and 19 > 81*20%=16.2). Actually, we should use 25% instead of 20% as the probability here, so that we have 19 < 81*25%=20.25, and the desired ABDC layout will be generated.
Reviewers: djasper, davidxl
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D20989
llvm-svn: 272203
Summary:
Now DISubroutineType has a 'cc' field which should be a DW_CC_ enum. If
it is present and non-zero, the backend will emit it as a
DW_AT_calling_convention attribute. On the CodeView side, we translate
it to the appropriate enum for the LF_PROCEDURE record.
I added a new LLVM vendor specific enum to the list of DWARF calling
conventions. DWARF does not appear to attempt to standardize these, so I
assume it's OK to do this until we coordinate with GCC on how to emit
vectorcall convention functions.
Reviewers: dexonsmith, majnemer, aaboud, amccarth
Subscribers: mehdi_amini, llvm-commits
Differential Revision: http://reviews.llvm.org/D21114
llvm-svn: 272197
with user specified count has been applied.
Summary:
Previously SetLoopAlreadyUnrolled() set the disable pragma only if
there was some loop metadata.
Now it set the pragma in all cases. This helps to prevent multiple
unroll when -unroll-count=N is given.
Reviewers: mzolotukhin
Differential Revision: http://reviews.llvm.org/D20765
From: Evgeny Stupachenko <evstupac@gmail.com>
llvm-svn: 272195
Again, the Microsoft linker does not like empty substreams.
We still emit an empty string table if CodeView is enabled, but that
doesn't cause problems because it always contains at least one null
byte.
llvm-svn: 272183
Absence of may-unwind calls is not enough to guarantee that a
UB-generating use of an add-rec poison in the loop latch will actually
cause UB. We also need to guard against calls that terminate the thread
or infinite loop themselves.
This partially addresses PR28012.
llvm-svn: 272181
The worklist algorithm introduced in rL271151 didn't check to see if the
direct users of the post-inc add recurrence propagates poison. This
change fixes the problem and makes the code structure more obvious.
Note for release managers: correctness wise, this bug wasn't a
regression introduced by rL271151 -- the behavior of SCEV around
post-inc add recurrences was strictly improved (in terms of correctness)
in rL271151.
llvm-svn: 272179
Teach AArch64RegisterBankInfo that G_OR can be mapped on either GPR or
FPR for 64-bit or 32-bit values.
Add test cases demonstrating how this information is used to coalesce a
computation on a single register bank.
llvm-svn: 272170
The MSR instructions can write to the CPSR, but we did not model this
fact, so we could emit them in the middle of IT blocks, changing the
condition flags for later instructions in the block.
The tests use two calls to llvm.write_register.i32 because it is valid
to use these instructions at the end of an IT block, which if conversion
does do in some cases. With two calls, the first clobbers the flags, so
a branch has to be used to make the second one conditional.
Differential Revision: http://reviews.llvm.org/D21139
llvm-svn: 272154
Changes since the initial commit:
- Use echo instead of printf. This should side-step the character
escaping issues on Windows.
Differential Revision: http://reviews.llvm.org/D20980
llvm-svn: 272068
Summary:
The presence of this attribute indicates that VGPR outputs should be computed
in whole quad mode. This will be used by Mesa for prolog pixel shaders, so
that derivatives can be taken of shader inputs computed by the prolog, fixing
a bug.
The generated code could certainly be improved: if a prolog pixel shader is
used (which isn't common in modern OpenGL - they're used for gl_Color, polygon
stipples, and forcing per-sample interpolation), Mesa will use this attribute
unconditionally, because it has to be conservative. So WQM may be used in the
prolog when it isn't really needed, and furthermore a silly back-and-forth
switch is likely to happen at the boundary between prolog and main shader
parts.
Fixing this is a bit involved: we'd first have to add a mechanism by which
LLVM writes the WQM-related input requirements to the main shader part binary,
and then Mesa specializes the prolog part accordingly. At that point, we may
as well just compile a monolithic shader...
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95130
Reviewers: arsenm, tstellarAMD, mareko
Subscribers: arsenm, llvm-commits, kzhuravl
Differential Revision: http://reviews.llvm.org/D20839
llvm-svn: 272063
Summary:
This patch is adding support for the MSVC buffer security check implementation
The buffer security check is turned on with the '/GS' compiler switch.
* https://msdn.microsoft.com/en-us/library/8dbf701c.aspx
* To be added to clang here: http://reviews.llvm.org/D20347
Some overview of buffer security check feature and implementation:
* https://msdn.microsoft.com/en-us/library/aa290051(VS.71).aspx
* http://www.ksyash.com/2011/01/buffer-overflow-protection-3/
* http://blog.osom.info/2012/02/understanding-vs-c-compilers-buffer.html
For the following example:
```
int example(int offset, int index) {
char buffer[10];
memset(buffer, 0xCC, index);
return buffer[index];
}
```
The MSVC compiler is adding these instructions to perform stack integrity check:
```
push ebp
mov ebp,esp
sub esp,50h
[1] mov eax,dword ptr [__security_cookie (01068024h)]
[2] xor eax,ebp
[3] mov dword ptr [ebp-4],eax
push ebx
push esi
push edi
mov eax,dword ptr [index]
push eax
push 0CCh
lea ecx,[buffer]
push ecx
call _memset (010610B9h)
add esp,0Ch
mov eax,dword ptr [index]
movsx eax,byte ptr buffer[eax]
pop edi
pop esi
pop ebx
[4] mov ecx,dword ptr [ebp-4]
[5] xor ecx,ebp
[6] call @__security_check_cookie@4 (01061276h)
mov esp,ebp
pop ebp
ret
```
The instrumentation above is:
* [1] is loading the global security canary,
* [3] is storing the local computed ([2]) canary to the guard slot,
* [4] is loading the guard slot and ([5]) re-compute the global canary,
* [6] is validating the resulting canary with the '__security_check_cookie' and performs error handling.
Overview of the current stack-protection implementation:
* lib/CodeGen/StackProtector.cpp
* There is a default stack-protection implementation applied on intermediate representation.
* The target can overload 'getIRStackGuard' method if it has a standard location for the stack protector cookie.
* An intrinsic 'Intrinsic::stackprotector' is added to the prologue. It will be expanded by the instruction selection pass (DAG or Fast).
* Basic Blocks are added to every instrumented function to receive the code for handling stack guard validation and errors handling.
* Guard manipulation and comparison are added directly to the intermediate representation.
* lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
* lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
* There is an implementation that adds instrumentation during instruction selection (for better handling of sibbling calls).
* see long comment above 'class StackProtectorDescriptor' declaration.
* The target needs to override 'getSDagStackGuard' to activate SDAG stack protection generation. (note: getIRStackGuard MUST be nullptr).
* 'getSDagStackGuard' returns the appropriate stack guard (security cookie)
* The code is generated by 'SelectionDAGBuilder.cpp' and 'SelectionDAGISel.cpp'.
* include/llvm/Target/TargetLowering.h
* Contains function to retrieve the default Guard 'Value'; should be overriden by each target to select which implementation is used and provide Guard 'Value'.
* lib/Target/X86/X86ISelLowering.cpp
* Contains the x86 specialisation; Guard 'Value' used by the SelectionDAG algorithm.
Function-based Instrumentation:
* The MSVC doesn't inline the stack guard comparison in every function. Instead, a call to '__security_check_cookie' is added to the epilogue before every return instructions.
* To support function-based instrumentation, this patch is
* adding a function to get the function-based check (llvm 'Value', see include/llvm/Target/TargetLowering.h),
* If provided, the stack protection instrumentation won't be inlined and a call to that function will be added to the prologue.
* modifying (SelectionDAGISel.cpp) do avoid producing basic blocks used for inline instrumentation,
* generating the function-based instrumentation during the ISEL pass (SelectionDAGBuilder.cpp),
* if FastISEL (not SelectionDAG), using the fallback which rely on the same function-based implemented over intermediate representation (StackProtector.cpp).
Modifications
* adding support for MSVC (lib/Target/X86/X86ISelLowering.cpp)
* adding support function-based instrumentation (lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp, .h)
Results
* IR generated instrumentation:
```
clang-cl /GS test.cc /Od /c -mllvm -print-isel-input
```
```
*** Final LLVM Code input to ISel ***
; Function Attrs: nounwind sspstrong
define i32 @"\01?example@@YAHHH@Z"(i32 %offset, i32 %index) #0 {
entry:
%StackGuardSlot = alloca i8* <<<-- Allocated guard slot
%0 = call i8* @llvm.stackguard() <<<-- Loading Stack Guard value
call void @llvm.stackprotector(i8* %0, i8** %StackGuardSlot) <<<-- Prologue intrinsic call (store to Guard slot)
%index.addr = alloca i32, align 4
%offset.addr = alloca i32, align 4
%buffer = alloca [10 x i8], align 1
store i32 %index, i32* %index.addr, align 4
store i32 %offset, i32* %offset.addr, align 4
%arraydecay = getelementptr inbounds [10 x i8], [10 x i8]* %buffer, i32 0, i32 0
%1 = load i32, i32* %index.addr, align 4
call void @llvm.memset.p0i8.i32(i8* %arraydecay, i8 -52, i32 %1, i32 1, i1 false)
%2 = load i32, i32* %index.addr, align 4
%arrayidx = getelementptr inbounds [10 x i8], [10 x i8]* %buffer, i32 0, i32 %2
%3 = load i8, i8* %arrayidx, align 1
%conv = sext i8 %3 to i32
%4 = load volatile i8*, i8** %StackGuardSlot <<<-- Loading Guard slot
call void @__security_check_cookie(i8* %4) <<<-- Epilogue function-based check
ret i32 %conv
}
```
* SelectionDAG generated instrumentation:
```
clang-cl /GS test.cc /O1 /c /FA
```
```
"?example@@YAHHH@Z": # @"\01?example@@YAHHH@Z"
# BB#0: # %entry
pushl %esi
subl $16, %esp
movl ___security_cookie, %eax <<<-- Loading Stack Guard value
movl 28(%esp), %esi
movl %eax, 12(%esp) <<<-- Store to Guard slot
leal 2(%esp), %eax
pushl %esi
pushl $204
pushl %eax
calll _memset
addl $12, %esp
movsbl 2(%esp,%esi), %esi
movl 12(%esp), %ecx <<<-- Loading Guard slot
calll @__security_check_cookie@4 <<<-- Epilogue function-based check
movl %esi, %eax
addl $16, %esp
popl %esi
retl
```
Reviewers: kcc, pcc, eugenis, rnk
Subscribers: majnemer, llvm-commits, hans, thakis, rnk
Differential Revision: http://reviews.llvm.org/D20346
llvm-svn: 272053
This patch does a few things:
- Unifies AttrAll and AttrUnknown (since they were used for more or less
the same purpose anyway).
- Introduces AttrEscaped, an attribute that notes that a value escapes
our analysis for a given set, but not that an unknown value flows into
said set.
- Removes functions that take bit indices, since we also had functions
that took bitsets, and the use of both (with similar names) was
unclear and bug-prone.
Patch by Jia Chen.
Differential Revision: http://reviews.llvm.org/D21000
llvm-svn: 272040
These instructions end in "S" but are not flag-setting, so they need including
in the list of special cases in the assembly parser.
Differential Revision: http://reviews.llvm.org/D21077
llvm-svn: 272015
Currently the only way to use the (V)MOVNTDQA nontemporal vector loads instructions is through the int_x86_sse41_movntdqa style builtins.
This patch adds support for lowering nontemporal loads from general IR, allowing us to remove the movntdqa builtins in a future patch.
We currently still fold nontemporal loads into suitable instructions, we should probably look at removing this (and nontemporal stores as well) or at least make the target's folding implementation aware that its dealing with a nontemporal memory transaction.
There is also an issue that VMOVNTDQA only acts on 128-bit vectors on pre-AVX2 hardware - so currently a normal ymm load is still used on AVX1 targets.
Differential Review: http://reviews.llvm.org/D20965
llvm-svn: 272010
Using an LLVM IR aggregate return value type containing three
or more integer values causes an abort in the fast isel pass.
This patch adds two more registers to RetCC_PPC64_ELF_FIS to
allow returning up to four integers with fast isel, just the
same as is currently supported with regular isel (RetCC_PPC).
This is needed for Swift and (possibly) other non-clang frontends.
Fixes PR26190.
llvm-svn: 272005
We currently only combine to blend+zero if the target value type has 8 elements or less, but this was missing a lot of cases where the combined mask had been widened.
This change makes it so we use the combined mask to determine the blend value type, allowing us to catch more widened cases.
llvm-svn: 272003
A Thumb-2 post-indexed LDR instruction such as:
ldr.w r0, [r1], #4
Can be rewritten as:
ldm.n r1!, {r0}
LDMs can be more expensive than LDRs on some cores, so this has been enabled only in minsize mode.
llvm-svn: 272002
If we have an LDM that uses only low registers and doesn't write to its base register:
ldm.w r0, {r1, r2, r3}
And that base register is dead after the LDM, then we can convert it to writeback form and use a narrow encoding:
ldm.n r0!, {r1, r2, r3}
Obviously, this introduces a new register write and so can cause WAW hazards, so I've enabled it only in minsize mode. This is a code size trick that ARM Compiler 5 ("armcc") does that we don't.
llvm-svn: 272000
SHT_GNU_verneed (.gnu.version_r) is a version dependency section.
It was the last symbol versioning relative section that was not dumped,
now it is.
Differential revision: http://reviews.llvm.org/D21024
llvm-svn: 271998
The Thumb2 conditional branch B<cond>.W has a different encoding (T3)
to the unconditional branch B.W (T4) as it needs to record <cond>.
As the encoding is different the B<cond>.W is given a different
relocation type.
ELF for the ARM Architecture 4.6.1.6 (Table-13) states that
R_ARM_THM_JUMP19 should be used for B<cond>.W. At present the
MC layer is using the R_ARM_THM_JUMP24 from B.W.
This change makes B<cond>.W use R_ARM_THM_JUMP19 and alters the
existing test that checks for R_ARM_THM_JUMP24 to expect
R_ARM_THM_JUMP19.
llvm-svn: 271997
Unlike native shifts, the AVX2 per-element shift instructions VPSRAV/VPSRLV/VPSLLV handle out of range shift values (logical shifts set the result to zero, arithmetic shifts splat the sign bit).
If the shift amount is constant we can sometimes convert these instructions to native shifts:
1 - if all shift amounts are in range then the conversion is trivial.
2 - out of range arithmetic shifts can be clamped to the (bitwidth - 1) (a legal shift amount) before conversion.
3 - logical shifts just return zero if all elements have out of range shift amounts.
In addition, UNDEF shift amounts are handled - either as an UNDEF shift amount in a native shift or as an UNDEF in the logical 'all out of range' zero constant special case for logical shifts.
Differential Revision: http://reviews.llvm.org/D19675
llvm-svn: 271996
