When the return value is not used (i.e. only care about the value in the memory), x86 does not have to use add to implement these. Instead, it can use add, sub, inc, dec instructions with the "lock" prefix.
This is currently implemented using a bit of instruction selection trick. The issue is the target independent pattern produces one output and a chain and we want to map it into one that just output a chain. The current trick is to select it into a merge_values with the first definition being an implicit_def. The proper solution is to add new ISD opcodes for the no-output variant. DAG combiner can then transform the node before it gets to target node selection.
Problem #2 is we are adding a whole bunch of x86 atomic instructions when in fact these instructions are identical to the non-lock versions. We need a way to add target specific information to target nodes and have this information carried over to machine instructions. Asm printer (or JIT) can use this information to add the "lock" prefix.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77582 91177308-0d34-0410-b5e6-96231b3b80d8
due to x86 encoding restrictions. This is currently off by default
because it may cause code quality regressions. This is for PR4572.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77565 91177308-0d34-0410-b5e6-96231b3b80d8
wide vectors. Likewise, change VSTn intrinsics to take separate arguments
for each vector in a multi-vector struct. Adjust tests accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77468 91177308-0d34-0410-b5e6-96231b3b80d8
- This change also makes it possible to switch between ARM / Thumb on a
per-function basis.
- Fixed thumb2 routine which expand reg + arbitrary immediate. It was using
using ARM so_imm logic.
- Use movw and movt to do reg + imm when profitable.
- Other code clean ups and minor optimizations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77300 91177308-0d34-0410-b5e6-96231b3b80d8
for now. Make the section switching directives more consistent
by not including \n and including \t for them all.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77107 91177308-0d34-0410-b5e6-96231b3b80d8
and make it more aggressive, we now put:
const int G2 __attribute__((weak)) = 42;
into the text (readonly) segment like gcc, previously we put
it into the data (readwrite) segment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77104 91177308-0d34-0410-b5e6-96231b3b80d8
the step value as unsigned, the start value and the addrec
itself still need to be treated as signed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77078 91177308-0d34-0410-b5e6-96231b3b80d8
on darwin with ".cstring" instead of ".section __TEXT,__cstring". They
are the same and the former is better. Remove this because this is no longer
magic pixie dust in the frontend.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77055 91177308-0d34-0410-b5e6-96231b3b80d8
Before:
adr r12, #LJTI3_0_0
ldr pc, [r12, +r0, lsl #2]
LJTI3_0_0:
.long LBB3_24
.long LBB3_30
.long LBB3_31
.long LBB3_32
After:
adr r12, #LJTI3_0_0
add pc, r12, +r0, lsl #2
LJTI3_0_0:
b.w LBB3_24
b.w LBB3_30
b.w LBB3_31
b.w LBB3_32
This has several advantages.
1. This will make it easier to optimize this to a TBB / TBH instruction +
(smaller) table.
2. This eliminate the need for ugly asm printer hack to force the address
into thumb addresses (bit 0 is one).
3. Same codegen for pic and non-pic.
4. This eliminate the need to align the table so constantpool island pass
won't have to over-estimate the size.
Based on my calculation, the later is probably slightly faster as well since
ldr pc with shifter address is very slow. That is, it should be a win as long
as the HW implementation can do a reasonable job of branch predict the second
branch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77024 91177308-0d34-0410-b5e6-96231b3b80d8
There's still a strict-aliasing violation here, but I don't feel like
dealing with that right now...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77005 91177308-0d34-0410-b5e6-96231b3b80d8
