SCEV currently fails to compute loop counts for nonunit stride
loops. This comes up frequently. It prevents loop optimization and
forces vectorization to insert extra loop checks.
For example:
void foo(int n, int *x) {
for (int i = 0; i < n; i += 3) {
x[i] = i;
x[i+1] = i+1;
x[i+2] = i+2;
}
}
We need to properly handle the case in which limit > INT_MAX-stride. In
the above case: n > INT_MAX-3. In this case the loop counter will step
beyond the limit and overflow at the same time. However, knowing that
signed integer overlow in undefined, we can assume the loop test
behavior is arbitrary after overflow. This obeys both C undefined
behavior rules, and the more strict LLVM poison value rules.
I'm finally fixing this in response to Hal Finkel's persistence.
The most probable reason that we never optimized this before is that
we were being careful to handle case where the developer expected a
side-effect free infinite loop relying on overflow:
for (int i = 0; i < n; i += s) {
++j;
}
return j;
If INT_MAX+1 is a multiple of s and n > INT_MAX-s, then we might
expect an infinite loop. However there are plenty of ways to achieve
this effect without relying on undefined behavior of signed overflow.
llvm-svn: 193015
With this commit, all DIEs created in CompileUnit will be added to parents
inside the same function. Also make getOrCreateTemplateType|Value functions
private.
No functionality change.
llvm-svn: 193002
This is another (final?) stab at making us able to parse our own asm output
on Windows.
Symbols on Windows often contain @'s and ?'s in their names. Our asm parser
didn't like this. ?'s were not allowed, and @'s were intepreted as trying to
reference PLT/GOT/etc.
We can't just add quotes around the bad names, since e.g. for MinGW, we use gas
to assemble, and it doesn't like quotes in some places (notably in .def
directives).
This commit makes us allow ?'s in symbol names, and @'s in symbol names for MS
assembly.
Differential Revision: http://llvm-reviews.chandlerc.com/D1978
llvm-svn: 193000
PR17168 describes a test case that fails when compiling for debug with
fast-isel. Investigation showed that the test was failing because a DBG_VALUE
machine instruction was placed prior to a PHI.
For this problem to occur requires the following:
* Compile for debug
* Compile with fast-isel
* In a block B, fast-isel must partially succeed before punting to DAG-isel
* B must start with a PHI
* The first unhandled node in the DAG must not generate a machine instruction
* A debug value with an order less than that of that first node exists
When all of these circumstances apply, the existing test that an instruction
was not inserted won't fire. Currently it tests whether the block is empty,
or whether the last instruction generated is a phi. When fast-isel has
partially succeeded, the last instruction generated will not be a phi.
Instead, we need to check whether the current insert position is immediately
following a phi. This patch adds that check, and adds the test case from the
PR as a regression test.
llvm-svn: 192976
There are targets that support i128 sized scalars but cannot emit
instructions that modify them directly. The proper thing to do is to
emit a libcall.
This fixes PR17481.
llvm-svn: 192957
gcc diagnoses this:
warning: converting to non-pointer type 'unsigned int' from NULL
Also remove an empty statement.
No change in functionality.
llvm-svn: 192955
This caused the clang-native-mingw32-win7 buildbot to break.
The assembler was complaining about the following lines that were showing up
in the asm for CrashRecoveryContext.cpp:
movl $"__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4", 4(%eax)
calll "_AddVectoredExceptionHandler@8"
.def "__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4";
"__ZL16ExceptionHandlerP19_EXCEPTION_POINTERS@4":
calll "_RemoveVectoredExceptionHandler@4"
Reverting for now.
llvm-svn: 192940
This commit implements the correct lowering of the
COPY_STRUCT_BYVAL_I32 pseudo-instruction for thumb1 targets.
Previously, the lowering of COPY_STRUCT_BYVAL_I32 generated the
post-increment forms of ldr/ldrh/ldrb instructions. Thumb1 does not
have the post-increment form of these instructions so the generated
assembly contained invalid instructions.
Passing the generated assembly to gcc caused it to complain with an
error like this:
Error: cannot honor width suffix -- `ldrb r3,[r0],#1'
and the integrated assembler would generate an object file with an
invalid instruction encoding.
This commit contains a small test case that demonstrates the problem
with thumb1 targets as well as an expanded test case that more
throughly tests the lowering of byval struct passing for arm,
thumb1, and thumb2 targets.
llvm-svn: 192916
This commit refactors the lowering of the COPY_STRUCT_BYVAL_I32
pseudo-instruction in the ARM backend. We introduce a new helper
class that encapsulates all of the operations needed during the
lowering. The operations are implemented for each subtarget in
different subclasses. Currently only arm and thumb2 subtargets are
supported.
This refactoring was done to easily implement support for thumb1
subtargets. This initial patch does not add support for thumb1, but
is only a refactoring. A follow on patch will implement the support
for thumb1 subtargets.
No intended functionality change.
llvm-svn: 192915
All of the Core API functions have versions which accept explicit context, in
addition to ones which work on global context. This commit adds functions
which accept explicit context to the Target API for consistency.
Patch by Peter Zotov
Differential Revision: http://llvm-reviews.chandlerc.com/D1912
llvm-svn: 192913
After r192904, Reid pointed out he thought we already set the stack
size for MSVC. Turns out we did, but it didn't seem to work.
This commit sets the stack size in a single place, using
CMAKE_EXE_LINKER_FLAGS because that seems to be the way that works
best.
llvm-svn: 192912
class. The instruction class includes the signed saturating doubling
multiply-add long, signed saturating doubling multiply-subtract long, and
the signed saturating doubling multiply long instructions.
llvm-svn: 192908
Compiling under Visual C++ 2012 with the default stack size of 1MB, the stack
overflows at a depth of 216 template instantiations, well before the 256
default limit. This patch modifies the default MSVC stack size to 2MB.
Patch by Yaron Keren!
llvm-svn: 192904
