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Author SHA1 Message Date
Ben Shi 25531a1d96 [AVR] Optimize 8-bit logic left/right shifts 
Reviewed By: dylanmckay

Differential Revision: https://reviews.llvm.org/D89047
 2021-01-23 23:54:16 +08:00
Ayke van Laethem 6afc3de42f
[AVR] Fix private label prefix 
This is a small pet peeve from me. This change makes sure the AVR backend uses
the correct private label prefix (.L) so that private labels are hidden in
avr-objdump.

Example code:

    define i8 @foo(i1 %cond) {
      br i1 %cond, label %then, label %else
    then:
      ret i8 3
    else:
      ret i8 5
    }

When compiling this:
  llc -march=avr -filetype=obj -o test.o test.ll
and then dumping it:
  avr-objdump -d test.o
You would previously get an ugly temporary label:

    00000000 <foo>:
       0:        81 70       andi       r24, 0x01    ; 1
       2:        80 30       cpi        r24, 0x00    ; 0
       4:        f9 f3       breq       .-2          ; 0x4 <foo+0x4>
       6:        83 e0       ldi        r24, 0x03    ; 3
       8:        08 95       ret

    0000000a <LBB0_2>:
       a:        85 e0       ldi        r24, 0x05    ; 5
       c:        08 95       ret

This patch fixes that, the output is now:

    00000000 <foo>:
       0:        81 70       andi       r24, 0x01    ; 1
       2:        80 30       cpi        r24, 0x00    ; 0
       4:        01 f0       breq       .+0          ; 0x6 <foo+0x6>
       6:        83 e0       ldi        r24, 0x03    ; 3
       8:        08 95       ret
       a:        85 e0       ldi        r24, 0x05    ; 5
       c:        08 95       ret

Note that as you can see the breq operand is different. However it is
still the same after linking:

       4:        11 f0       breq       .+4

Differential Revision: https://reviews.llvm.org/D75124
 2020-02-26 20:32:25 +01:00
Dylan McKay 9cf1dc1e0f [AVR] Use the generic branch relaxer 
llvm-svn: 307617
 2017-07-11 04:17:13 +00:00
Dylan McKay a24aa19900 Revert "[AVR] Add the branch selection pass from the GitHub repository" 
This reverts commit 602ef067c1d58ecb425d061f35f2bc4c7e92f4f3.

llvm-svn: 307111
 2017-07-05 00:50:56 +00:00
Dylan McKay f115c7f917 [AVR] Add the branch selection pass from the GitHub repository 
We should rewrite this using the generic branch relaxation pass, but for
the moment having this pass is better than hitting an assertion error.

llvm-svn: 307109
 2017-07-05 00:41:19 +00:00
Dylan McKay 6dd69032c9 [AVR] Fix basic block naming in ctlz and cttz tests 
The branch selector would change the names.

llvm-svn: 287174
 2016-11-16 22:48:38 +00:00
Dylan McKay 9701c42de9 [AVR] Add tests for counting leading/trailing zeros 
This adds two test files that verify the 'cttz' and 'ctlz' operations.

llvm-svn: 287172
 2016-11-16 22:38:43 +00:00