Summary:
Fix the computation of the offsets present in the scopetable when using the
SEH (__except_handler4).
This patch added an intrinsic to track the position of the allocation on the
stack of the EHGuard. This position is needed when producing the ScopeTable.
```
struct _EH4_SCOPETABLE {
DWORD GSCookieOffset;
DWORD GSCookieXOROffset;
DWORD EHCookieOffset;
DWORD EHCookieXOROffset;
_EH4_SCOPETABLE_RECORD ScopeRecord[1];
};
struct _EH4_SCOPETABLE_RECORD {
DWORD EnclosingLevel;
long (*FilterFunc)();
union {
void (*HandlerAddress)();
void (*FinallyFunc)();
};
};
```
The code to generate the EHCookie is added in `X86WinEHState.cpp`.
Which is adding these instructions when using SEH4.
```
Lfunc_begin0:
# BB#0: # %entry
pushl %ebp
movl %esp, %ebp
pushl %ebx
pushl %edi
pushl %esi
subl $28, %esp
movl %ebp, %eax <<-- Loading FramePtr
movl %esp, -36(%ebp)
movl $-2, -16(%ebp)
movl $L__ehtable$use_except_handler4_ssp, %ecx
xorl ___security_cookie, %ecx
movl %ecx, -20(%ebp)
xorl ___security_cookie, %eax <<-- XOR FramePtr and Cookie
movl %eax, -40(%ebp) <<-- Storing EHGuard
leal -28(%ebp), %eax
movl $__except_handler4, -24(%ebp)
movl %fs:0, %ecx
movl %ecx, -28(%ebp)
movl %eax, %fs:0
movl $0, -16(%ebp)
calll _may_throw_or_crash
LBB1_1: # %cont
movl -28(%ebp), %eax
movl %eax, %fs:0
addl $28, %esp
popl %esi
popl %edi
popl %ebx
popl %ebp
retl
```
And the corresponding offset is computed:
```
Luse_except_handler4_ssp$parent_frame_offset = -36
.p2align 2
L__ehtable$use_except_handler4_ssp:
.long -2 # GSCookieOffset
.long 0 # GSCookieXOROffset
.long -40 # EHCookieOffset <<----
.long 0 # EHCookieXOROffset
.long -2 # ToState
.long _catchall_filt # FilterFunction
.long LBB1_2 # ExceptionHandler
```
Clang is not yet producing function using SEH4, but it's a work in progress.
This patch is a step toward having a valid implementation of SEH4.
Unfortunately, it is not yet fully working. The EH registration block is not
allocated at the right offset on the stack.
Reviewers: rnk, majnemer
Subscribers: llvm-commits, chrisha
Differential Revision: http://reviews.llvm.org/D21231
llvm-svn: 273281
When you have a map holding a unique_ptr, hold a reference to the raw
pointer instead of the unique pointer. The unique_ptr will be moved on
rehash.
llvm-svn: 273268
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
Summary:
Using isOutOfOrder makes the code more clear.
Reviewers: rengolin, atrick, hfinkel.
Differential Revision: http://reviews.llvm.org/D21548
llvm-svn: 273255
An incomplete member pointer type will always have a size of zero, so we
don't need an extra flag. Credit to David Majnemer for the idea.
llvm-svn: 273057
Summary:
This seems like the least intrusive way to pass this information
through.
Fixes PR28151
Reviewers: majnemer, aprantl, dblaikie
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D21444
llvm-svn: 273053
Many CPUs only have the ability to do a 4-byte cmpxchg (or ll/sc), not 1
or 2-byte. For those, you need to mask and shift the 1 or 2 byte values
appropriately to use the 4-byte instruction.
This change adds support for cmpxchg-based instruction sets (only SPARC,
in LLVM). The support can be extended for LL/SC-based PPC and MIPS in
the future, supplanting the ISel expansions those architectures
currently use.
Tests added for the IR transform and SPARCv9.
Differential Revision: http://reviews.llvm.org/D21029
llvm-svn: 273025
Names in function id records don't include nested name specifiers or
template arguments, but names in the symbol stream include both.
For the symbol stream, instead of having Clang put the fully qualified
name in the subprogram display name, recreate it from the subprogram
scope chain. For the type stream, take the unqualified name and chop of
any template arguments.
This makes it so that CodeView DI metadata is more similar to DWARF DI
metadata.
llvm-svn: 273009
This is a fix for PR27844.
When replacing uses of unsafe allocas, emit the new location
immediately after each use. Without this, the pointer stays live from
the function entry to the last use, while it's usually cheaper to
recalculate.
llvm-svn: 272969
When moving unsafe allocas to the unsafe stack, dbg.declare intrinsics are
updated to refer to the new location.
This change does the same to dbg.value intrinsics.
llvm-svn: 272968
MSVC handles enums differently from structs and classes: a forward
declaration is not emitted unconditionally. MSVC does not emit an S_UDT
record for the enum.
Differential Revision: http://reviews.llvm.org/D21442
llvm-svn: 272960
Summary:
... into getFrameIndexReferencePreferSP. This change folds the
fail-then-retry logic into getFrameIndexReferencePreferSP.
There is a non-functional but behaviorial change in WinException --
earlier if `getFrameIndexReferenceFromSP` failed we'd trip an assert,
but now we'll silently use the (wrong) offset from the base pointer. I
could not write the assert I'd like to write ("FrameReg ==
StackRegister", like I've done in X86FrameLowering) since there is no
easy way to get to the stack register from WinException (happy to be
proven wrong here). One solution to this is to add a `bool
OnlyStackPointer` parameter to `getFrameIndexReferenceFromSP` that
asserts if it could not satisfy its promise of returning an offset from
a stack pointer, but that seems overkill.
Reviewers: rnk
Subscribers: sanjoy, mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D21427
llvm-svn: 272938
This allows better catching of compiler errors since we can use
the override keyword to verify that methods are actually
overridden.
Also in this patch I've changed from storing a boolean Error
code everywhere to returning an llvm::Error, to propagate richer
error information up the call stack.
Reviewed By: ruiu, rnk
Differential Revision: http://reviews.llvm.org/D21410
llvm-svn: 272926
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
Emit a S_UDT record for typedefs. We still need to do something for
class types.
Differential Revision: http://reviews.llvm.org/D21149
llvm-svn: 272813
[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
Summary:
... when the offset is not statically known.
Prioritize addresses relative to the stack pointer in the stackmap, but
fallback gracefully to other modes of addressing if the offset to the
stack pointer is not a known constant.
Patch by Oscar Blumberg!
Reviewers: sanjoy
Subscribers: llvm-commits, majnemer, rnk, sanjoy, thanm
Differential Revision: http://reviews.llvm.org/D21259
llvm-svn: 272756
Document the new parameter and threshod computation
model. Also fix a bug when the threshold parameter
is set to be different from the default.
llvm-svn: 272749
Summary: With runtime profile, we have more confidence in branch probability, thus during basic block layout, we set a lower hot prob threshold so that blocks can be layouted optimally.
Reviewers: djasper, davidxl
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D20991
llvm-svn: 272729
If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.
This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
the normal rule that the global must have a unique address can be broken without
being observable by the program by performing comparisons against the global's
address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
its own copy of the global if it requires one, and the copy in each linkage unit
must be the same)
- It is a constant or a function (which means that the program cannot observe that
the unique-address rule has been broken by writing to the global)
Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.
See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.htmlhttp://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.
Part of the fix for PR27553.
Differential Revision: http://reviews.llvm.org/D20348
llvm-svn: 272709
Summary:
Split NumInstrDups statistic into separate added/removed counts to avoid
negative stat being printed as unsigned.
Subscribers: mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D21335
llvm-svn: 272700
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
Change EmitGlobalVariable to check final assembler section is in BSS
before using .lcomm/.comm directive. This prevents globals from being
put into .bss erroneously when -data-sections is used.
This fixes PR26570.
Reviewers: echristo, rafael
Subscribers: llvm-commits, mehdi_amini
Differential Revision: http://reviews.llvm.org/D21146
llvm-svn: 272674
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
Save machine function pointer so that
the reference does not need to be passed around.
This also gives other methods access to machine
function for information such as entry count etc.
llvm-svn: 272594
This is third patch to clean up the code.
Included in this patch:
1. Further unclutter trace/chain formation main routine;
2. Isolate the logic to compute global cost/conflict detection
into its own method;
3. Heavily document the selection algorithm;
4. Added helper hook to allow PGO specific logic to be
added in the future.
llvm-svn: 272582
This is second patch to clean up the code.
In this patch, the logic to determine block outlinining
is refactored and more comments are added.
llvm-svn: 272514
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
This is one of the patches to clean up the code so that
it is in a better form to make future enhancements easier.
In htis patch, the logic to collect viable successors are
extrated as a helper to unclutter the caller which gets very
large recenty. Also cleaned up BP adjustment code.
llvm-svn: 272482
undef uses are no real uses of a register and must be ignored by
findLastUseBefore() so that handleMove() does not produce invalid live
intervals in some cases.
This fixed http://llvm.org/PR28083
llvm-svn: 272446
Summary:
When stack-protection is activated and WinEH exceptions is used,
the EHRegNode (exception handling registration) is allocated twice on the stack.
This was not breaking anything except loosing space on the stack.
```
D:\src\llvm\examples>llc exc2.ll -debug-only=pei
alloc FI(0) at SP[-24]
alloc FI(1) at SP[-48] <<-- Allocated
alloc FI(1) at SP[-72] <<-- Allocated twice!?
alloc FI(2) at SP[-76]
alloc FI(4) at SP[-80]
alloc FI(3) at SP[-84]
```
Reviewers: rnk, majnemer
Subscribers: chrisha, llvm-commits
Differential Revision: http://reviews.llvm.org/D21188
llvm-svn: 272426
Adds a MachineFunctionPass that scans the body to find calls, and
update the register mask with the one saved by the
RegUsageInfoCollector analysis in PhysicalRegisterUsageInfo.
Patch by Vivek Pandya <vivekvpandya@gmail.com>
Differential Revision: http://reviews.llvm.org/D21180
llvm-svn: 272414
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
When we delete a live-range, we check if that live-range is the origin of others
to keep it around for rematerialization. For that we check that the instruction
we are about to remove is the same as the definition of the VNI of the original
live-range.
If this is the case, we just shrink the live-range to an empty one.
Now, when we try to delete one of the children of such live-range (product of
splitting), we do the same check.
However, now the original live-range is empty and there is no way we can
access the VNI to check its definition, and we crash.
When we cannot get the VNI for the original live-range, that means we are not in
the presence of the original definition. Thus, this check does not need to happen
in that case and the crash is sloved!
This bug was introduced in r266162 | wmi | 2016-04-12 20:08:27. It affects every
target that uses the greedy register allocator.
To happen, we need to delete both a the original instruction and its split
products, in that order. This is likely to happen when rematerialization comes
into play.
Trying to produce a more robust test case. Will follow in a coming commit.
This fixes llvm.org/PR27983.
rdar://problem/26651519
llvm-svn: 272314
This reapplies commit r271930, r271915, r271923. They hit a bug in
Thumb which is fixed in r272258 now.
The original message:
The code layout that TailMerging (inside BranchFolding) works on is not the
final layout optimized based on the branch probability. Generally, after
BlockPlacement, many new merging opportunities emerge.
This patch calls Tail Merging after MBP and calls MBP again if Tail Merging
merges anything.
llvm-svn: 272267
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
For complex rewrittings, which do not occur currently, the related
machine instruction may have been deleted in the process. Therefore, do
not try to print it after the mapping is applied.
llvm-svn: 272209
Refactor the code so that we do not compute in two different places the
end iterator for the range of new virtual registers for a given operand.
Although this refactoring was intended as NFC, this is not the case
because it actually fixes a bug where we were returning a range off by 1
(too long). Right now, this could not result in an actual bug because we
were accessing this range via the BreakDown size of the related operand.
llvm-svn: 272208
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
When repairing with a copy, instead of accounting for the cost of that
copy and actually inserting it, we may be able to use an alternative
source for the register to repair and just use it.
Make sure this is documented, so that we consider that opportunity at
some point.
llvm-svn: 272176
Now, the target will be able to provide its how implementation to remap
an instruction. This open the way to crazier optimizations, but to
beginning with, we will be able to handle something else than the
default mapping.
llvm-svn: 272165
When the command line option is set, it overrides any thing that the
target may have set. The rationale is that we get what we asked for.
Options are respectively regbankselect-fast and regbankselect-greedy for
fast and greedy mode.
llvm-svn: 272158
repairing.
Copies are easy because we repair only when there is a mismatch. For
non-copy repairing, i.e., cases that involves breaking down or gathering
up the value, one of the operand may not have a register bank yet. Thus,
derivate a cost from that, requires more work.
llvm-svn: 272157
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
The cost of a copy may be different based on how many bits we have to
copy around. E.g., a 8-bit copy may be different than a 32-bit copy.
llvm-svn: 272084
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 reverts commit r271962 and reinstantes r271957.
MSVC's linker doesn't appear to like it if you have an empty symbol
substream, so only open a symbol substream if we're going to emit
something about globals into it.
Makes check-asan pass.
llvm-svn: 271965
The code layout that TailMerging (inside BranchFolding) works on is not the
final layout optimized based on the branch probability. Generally, after
BlockPlacement, many new merging opportunities emerge.
This patch calls Tail Merging after MBP and calls MBP again if Tail Merging
merges anything.
Differential Revision: http://reviews.llvm.org/D20276
llvm-svn: 271925
C++ has a builtin type called wchar_t. Clang also provides a type
called __wchar_t in C mode.
In C mode, wchar_t can be a typedef to unsigned short.
llvm-svn: 271793
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
Rafael Espindola