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6cb2dcb661
Summary:
After SNB, Intel CPUs can rename CF independently of other EFLAGS,
so the renamer can zero it for free. Note that STC still consumes resources.
To reproduce: `$ llvm-exegesis -mode=uops -opcode-name=CLC`
On SNB:
```
---
key:
opcode_name: CLC
mode: uops
config: ''
cpu_name: sandybridge
llvm_triple: x86_64-unknown-linux-gnu
num_repetitions: 10000
measurements:
- { key: '3', value: 0.0014, debug_string: SBPort0 }
- { key: '4', value: 0.0013, debug_string: SBPort1 }
- { key: '5', value: 0.0003, debug_string: SBPort4 }
- { key: '6', value: 0.0029, debug_string: SBPort5 }
- { key: '10', value: 0.0003, debug_string: SBPort23 }
error: ''
info: 'instruction is serial, repeating a random one.
Snippet:
CLC
'
...
```
On HSW:
```
---
key:
opcode_name: CLC
mode: uops
config: ''
cpu_name: haswell
llvm_triple: x86_64-unknown-linux-gnu
num_repetitions: 10000
measurements:
- { key: '3', value: 0.001, debug_string: HWPort0 }
- { key: '4', value: 0.0009, debug_string: HWPort1 }
- { key: '5', value: 0.0004, debug_string: HWPort2 }
- { key: '6', value: 0.0006, debug_string: HWPort3 }
- { key: '7', value: 0.0002, debug_string: HWPort4 }
- { key: '8', value: 0.0012, debug_string: HWPort5 }
- { key: '9', value: 0.0022, debug_string: HWPort6 }
- { key: '10', value: 0.0001, debug_string: HWPort7 }
error: ''
info: 'instruction is serial, repeating a random one.
Snippet:
CLC
'
...
```
Reviewers: craig.topper, RKSimon
Subscribers: gchatelet, llvm-commits
Differential Revision: https://reviews.llvm.org/D47362
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333392 91177308-0d34-0410-b5e6-96231b3b80d8