Recommiting after fixing over-aggressive assertion
[DAG] Previously debug values would transfer debuginfo for the selected
start node for a replacement which allows for debug to be dropped.
Push debug value transfer to occur with node/value replacement in
SelectionDAG, remove now extraneous transfers of debug values.
This refixes PR9817 which was being incompletely checked in the
testsuite.
Reviewers: jyknight
Subscribers: dblaikie, llvm-commits
Differential Revision: http://reviews.llvm.org/D21037
llvm-svn: 273456
The setCallee function will set the number of fixed arguments based
on the size of the argument list. The FixedArgs parameter was often
explicitly set to 0, leading to a lack of consistent value for non-
vararg functions.
Differential Revision: http://reviews.llvm.org/D20376
llvm-svn: 273403
Summary:
canCombineSinCosLibcall() would previously combine sin+cos into sincos for
GNUX32/GNUEABI/GNUEABIHF regardless of whether UnsafeFPMath were set or not.
However, GNU would only combine them for UnsafeFPMath because sincos does not
set errno like sin and cos do. It seems likely that this is an oversight.
Reviewers: t.p.northover
Subscribers: t.p.northover, aemerson, llvm-commits, rengolin
Differential Revision: http://reviews.llvm.org/D21431
llvm-svn: 273259
When calculating a square root using Newton-Raphson with two constants,
a naive implementation is to use five multiplications (four muls to calculate
reciprocal square root and another one to calculate the square root itself).
However, after some reassociation and CSE the same result can be obtained
with only four multiplications. Unfortunately, there's no reliable way to do
such a reassociation in the back-end. So, the patch modifies NR code itself
so that it directly builds optimal code for SQRT and doesn't rely on any
further reassociation.
Patch by Nikolai Bozhenov!
Differential Revision: http://reviews.llvm.org/D21127
llvm-svn: 272920
[DAG] Previously debug values would transfer debuginfo for the selected
start node for a replacement which allows for debug to be dropped.
Push debug value transfer to occur with node/value replacement in
SelectionDAG, remove now extraneous transfers of debug values.
This refixes PR9817 which was being incompletely checked in the
testsuite.
Reviewers: jyknight
Subscribers: dblaikie, llvm-commits
Differential Revision: http://reviews.llvm.org/D21037
llvm-svn: 272792
For <N x i32> type mul, pmuludq will be used for targets without SSE41, which
often introduces many extra pack and unpack instructions in vectorized loop
body because pmuludq generates <N/2 x i64> type value. However when the operands
of <N x i32> mul are extended from smaller size values like i8 and i16, the type
of mul may be shrunk to use pmullw + pmulhw/pmulhuw instead of pmuludq, which
generates better code. For targets with SSE41, pmulld is supported so no
shrinking is needed.
Differential Revision: http://reviews.llvm.org/D20931
llvm-svn: 272694
The exit-on-error flag in the ARM test is necessary in order to avoid an
unreachable in the DAGTypeLegalizer, when trying to expand a physical register.
We can also avoid this situation by introducing a bitcast early on, where the
invalid scalar-to-vector conversion is detected.
We also add a test for PowerPC, which goes through a similar code path in the
SelectionDAGBuilder.
Fixes PR27765.
Differential Revision: http://reviews.llvm.org/D21061
llvm-svn: 272644
This used to be free, copying and moving DebugLocs became expensive
after the metadata rewrite. Passing by reference eliminates a ton of
track/untrack operations. No functionality change intended.
llvm-svn: 272512
As suggested by clang-tidy's performance-unnecessary-copy-initialization.
This can easily hit lifetime issues, so I audited every change and ran the
tests under asan, which came back clean.
llvm-svn: 272126
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
My first attempt at this had an overly aggressive assert - chain nodes
will only be removed, but we could hit the assert if a non-chain node
was CSE'd (NodeToMatch, for instance).
This reapplies r271706 by reverting r271713 and fixing an assert.
Original message:
Avoid relying on UB by looking into deleted nodes for a marker value.
Instead, update the list of chain nodes as we go.
llvm-svn: 271733
Although this was intended to be NFC, the test case wiggle shows a change in
code scheduling/RA caused by a difference in the SDLoc() generation.
Depending on how you look at it, this is the (dis)advantage of exact checking
in regression tests.
llvm-svn: 271526
When the index is known to be constant 0, insert directly into the the low half,
instead of spilling, performing the insert in-memory, and reloading.
Differential Revision: http://reviews.llvm.org/D20763
llvm-svn: 271428
This should have been converting the size to bytes, but wasn't really.
These should probably all be using getStoreSize instead.
I haven't been able to come up with a meaningful testcase for this.
I can trigger it using combinations of struct loads and stores,
but can't observe a difference in non-broken testcases.
isAlias is only really used during store merging, so I'm not sure how
to get into the vector splitting situation the comment describes
since store merging is only done before type legalization.
llvm-svn: 271356
We think it's OK to generate half fminnan because it's legal for the
transform-to type (f32; r245196). However, PromoteFloatRes was missing
the case; simply promote like the other binops, including minnum.
llvm-svn: 271317
LegalizeIntegerTypes does not have a way to expand multiplications for large
integer types (i.e. larger than twice the native bit width). There's no
standard runtime call to use in that case, and so we'd just assert.
Unfortunately, as it turns out, it is possible to hit this case from
standard-ish C code in rare cases. A particular case a user ran into yesterday
involved an __int128 induction variable and a loop with a quadratic (not
linear) recurrence which triggered some backend logic using SCEVExpander. In
this case, the BinomialCoefficient code in SCEV generates some i129 variables,
which get widened to i256. At a high level, this is not actually good (i.e. the
underlying optimization, PPCLoopPreIncPrep, should not be transforming the loop
in question for performance reasons), but regardless, the backend shouldn't
crash because of cost-modeling issues in the optimizer.
This is a straightforward implementation of the multiplication expansion, based
on the algorithm in Hacker's Delight. I validated it against the code for the
mul256b function from http://locklessinc.com/articles/256bit_arithmetic/ using
random inputs. There should be no functional change for previously-working code
(the new expansion code only replaces an assert).
Fixes PR19797.
llvm-svn: 270720
There are at least 2 places (DAGCombiner, X86ISelLowering) where this could be used instead
of ad-hoc and watered down code that is trying to match a power-of-2 pattern.
Differential Revision: http://reviews.llvm.org/D20439
llvm-svn: 270073
When processing inline asm that contains errors, make sure we can recover
gracefully by creating an UNDEF SDValue for the inline asm statement before
returning from SelectionDAGBuilder::visitInlineAsm. This is necessary for
consumers that don't exit on the first error that is emitted (e.g. clang)
and that would assert later on.
Fixes PR24071.
Patch by Diana Picus.
llvm-svn: 269811
Allow two users of the condition if the other user
is also a min/max select. i.e.
%c = icmp slt i32 %x, %y
%min = select i1 %c, i32 %x, i32 %y
%max = select i1 %c, i32 %y, i32 %x
llvm-svn: 269699
For BITREVERSE, bit shifting/masking every bit in a vector element is a very lengthy procedure.
If the input vector type is a whole multiple of bytes wide then we can split this into a BSWAP shuffle stage (to reverse at the byte level) and then a BITREVERSE stage applied to each byte. Most vector capable targets can efficiently BSWAP using shuffles resulting in a considerable reduction in instructions.
With this patch targets would only need to implement a target specific vXi8 BITREVERSE implementation to efficiently reverse most legal vector types.
Differential Revision: http://reviews.llvm.org/D19978
llvm-svn: 269290
It's awkward to force callers of SelectNodeTo to figure out whether
the node was morphed or CSE'd. Update uses here instead of requiring
callers to (sometimes) do it.
llvm-svn: 269235
This means SelectCode unconditionally returns nullptr now. I'll follow
up with a change to make that return void as well, but it seems best
to keep that one very mechanical.
This is part of the work to have Select return void instead of an
SDNode *, which is in turn part of llvm.org/pr26808.
llvm-svn: 269136
Currently, SelectionDAG assumes 8/16-bit cmpxchg returns either a sign
extended result, or a zero extended result. SystemZ takes a third
option by returning junk in the high bits (rotated contents of the other
bytes in the memory word). In that case, don't use Assert*ext, and
zero-extend the result ourselves if a comparison is needed.
Differential Revision: http://reviews.llvm.org/D19800
llvm-svn: 269075
After looking at D19087 again, it occurred to me that we can do better. If we consolidate
the valueHasExactlyOneBitSet() transforms, we won't incur extra overhead from calling it a
2nd time, and we can shrink SimplifySetCC() a bit. No functional change intended.
Differential Revision: http://reviews.llvm.org/D20050
llvm-svn: 268932
Nirav Dave