In this instance we are generating the tail-call during legalizeDAG. The 2nd
floor call can't be a tail call because it clobbers %xmm1, which is defined by
the first floor call. The first floor call can't be a tail-call because it's
not in the tail position. The only reasonable way I could think to fix this
in a target-independent manner was to check for glue logic on the copy reg.
rdar://10930395
llvm-svn: 151877
the processor keeps a return addresses stack (RAS) which stores the address
and the instruction execution state of the instruction after a function-call
type branch instruction.
Calling a "noreturn" function with normal call instructions (e.g. bl) can
corrupt RAS and causes 100% return misprediction so LLVM should use a
unconditional branch instead. i.e.
mov lr, pc
b _foo
The "mov lr, pc" is issued in order to get proper backtrace.
rdar://8979299
llvm-svn: 151623
[Joe Groff] Hi everyone. My previous patch applied as r151382 had a few problems:
Clang raised a warning, and X86 LowerOperation would assert out for
fptoui f64 to i32 because it improperly lowered to an illegal
BUILD_PAIR. Here's a patch that addresses these issues. Let me know if
any other changes are necessary. Thanks.
llvm-svn: 151432
rdar://10873652
As part of this I updated the llvm-mc disassembler C API to always call the
SymbolLookUp call back even if there is no getOpInfo call back. If there is a
getOpInfo call back that is tried first and then if that gets no information
then the SymbolLookUp is called. I also made the code more robust by
memset(3)'ing to zero the LLVMOpInfo1 struct before then setting
SymbolicOp.Value before for the call to getOpInfo. And also don't use any
values from the LLVMOpInfo1 struct if getOpInfo returns 0. And also don't
use any of the ReferenceType or ReferenceName values from SymbolLookUp if it
returns NULL. rdar://10873563 and rdar://10873683
For the X86 target also fixed bugs so the annotations get printed.
Also fixed a few places in the ARM target that was not producing symbolic
operands for some instructions. rdar://10878166
llvm-svn: 151267
Call clobbers are now represented with register mask operands. The
regmask can easily represent the fact that xmm6 is call-preserved while
ymm6 isn't. This is automatically computed by TableGen from the
CalleeSavedRegs containing xmm6.
llvm-svn: 150709
Call instructions no longer have a list of 43 call-clobbered registers.
Instead, they get a single register mask operand with a bit vector of
call-preserved registers.
This saves a lot of memory, 42 x 32 bytes = 1344 bytes per call
instruction, and it speeds up building call instructions because those
43 imp-def operands no longer need to be added to use-def lists. (And
removed and shifted and re-added for every explicit call operand).
Passes like LiveVariables, LiveIntervals, RAGreedy, PEI, and
BranchFolding are significantly faster because they can deal with call
clobbers in bulk.
Overall, clang -O2 is between 0% and 8% faster, uniformly distributed
depending on call density in the compiled code. Debug builds using
clang -O0 are 0% - 3% faster.
I have verified that this patch doesn't change the assembly generated
for the LLVM nightly test suite when building with -disable-copyprop
and -disable-branch-fold.
Branch folding behaves slightly differently in a few cases because call
instructions have different hash values now.
Copy propagation flushes its data structures when it crosses a register
mask operand. This causes it to leave a few dead copies behind, on the
order of 20 instruction across the entire nightly test suite, including
SPEC. Fixing this properly would require the pass to use different data
structures.
llvm-svn: 150638
- Use unsigned literals when the desired result is unsigned. This mostly allows unsigned/signed mismatch warnings to be less noisy even if they aren't on by default.
- Remove misplaced llvm_unreachable.
- Add static to a declaration of a function on MSVC x86 only.
- Change some instances of calling a static function through a variable to simply calling that function while removing the unused variable.
llvm-svn: 150364
If the DEC node had more than one user, it was doing this lowering but
leaving the original DEC node around and so decrementing twice.
Fixes PR11964.
llvm-svn: 150356
