Don't fall back on breaking apart the popcount operation if 128-bit
integers are natively supported.
Signed-off-by: Andy Sadler <andrewsadler122@gmail.com>
In the current implementation, the gcc backend of rustc currently emits the
following for a function that implements popcount for a u32 (x86_64 targeting
AVX2, using standard unix calling convention):
popcount:
mov eax, edi
and edi, 1431655765
shr eax
and eax, 1431655765
add edi, eax
mov edx, edi
and edi, 858993459
shr edx, 2
and edx, 858993459
add edx, edi
mov eax, edx
and edx, 252645135
shr eax, 4
and eax, 252645135
add eax, edx
mov edx, eax
and eax, 16711935
shr edx, 8
and edx, 16711935
add edx, eax
movzx eax, dx
shr edx, 16
add eax, edx
ret
Rather than using this implementation, gcc could be told to use Wenger's
algorithm. This would give the same function the following implementation:
popcount:
xor eax, eax
xor edx, edx
popcnt eax, edi
test edi, edi
cmove eax, edx
ret
This patch implements the popcount operation in terms of Wenger's algorithm in
all cases.
Signed-off-by: Andy Sadler <andrewsadler122@gmail.com>
This fixes the changes brought to codegen tests when effect params are
added to libcore, by not attempting to monomorphize functions that get
the host param by being `const fn`.
codegen_llvm/llvm_type: avoid matching on the Rust type
This `match` is highly suspicious. Looking at `scalar_llvm_type_at` I think it makes no difference. But if it were to make a difference that would be a huge problem, since it doesn't look through `repr(transparent)`!
Cc `@eddyb` `@bjorn3`
Use the same DISubprogram for each instance of the same inlined function within a caller
# Issue Details:
The call to `panic` within a function like `Option::unwrap` is translated to LLVM as a `tail call` (as it will never return), when multiple calls to the same function like this is inlined LLVM will notice the common `tail call` block (i.e., loading the same panic string + location info and then calling `panic`) and merge them together.
When merging these instructions together, LLVM will also attempt to merge the debug locations as well, but this fails (i.e., debug info is dropped) as Rust emits a new `DISubprogram` at each inline site thus LLVM doesn't recognize that these are actually the same function and so thinks that there isn't a common debug location.
As an example of this when building for x86_64 Windows (note the lack of `.cv_loc` before the call to `panic`, thus it will be attributed to the same line at the `addq` instruction):
```
.cv_loc 0 1 23 0 # src\lib.rs:23:0
addq $40, %rsp
retq
leaq .Lalloc_f570dea0a53168780ce9a91e67646421(%rip), %rcx
leaq .Lalloc_629ace53b7e5b76aaa810d549cc84ea3(%rip), %r8
movl $43, %edx
callq _ZN4core9panicking5panic17h12e60b9063f6dee8E
int3
```
# Fix Details:
Cache the `DISubprogram` emitted for each inlined function instance within a caller so that this can be reused if that instance is encountered again, this also requires caching the `DILexicalBlock` and `DIVariable` objects to avoid creating duplicates.
After this change the above assembly now looks like:
```
.cv_loc 0 1 23 0 # src\lib.rs:23:0
addq $40, %rsp
retq
.cv_inline_site_id 5 within 0 inlined_at 1 0 0
.cv_inline_site_id 6 within 5 inlined_at 1 12 0
.cv_loc 6 2 935 0 # library\core\src\option.rs:935:0
leaq .Lalloc_5f55955de67e57c79064b537689facea(%rip), %rcx
leaq .Lalloc_e741d4de8cb5801e1fd7a6c6795c1559(%rip), %r8
movl $43, %edx
callq _ZN4core9panicking5panic17hde1558f32d5b1c04E
int3
```
