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Diffstat (limited to 'llvm/docs/CommandGuide/llvm-mca.rst')
| -rw-r--r-- | llvm/docs/CommandGuide/llvm-mca.rst | 37 |
1 files changed, 33 insertions, 4 deletions
diff --git a/llvm/docs/CommandGuide/llvm-mca.rst b/llvm/docs/CommandGuide/llvm-mca.rst index f2ebbec43c0..4f8704ad9a9 100644 --- a/llvm/docs/CommandGuide/llvm-mca.rst +++ b/llvm/docs/CommandGuide/llvm-mca.rst @@ -174,6 +174,10 @@ option specifies "``-``", then the output will also be sent to standard output. Enable the instruction info view. This is enabled by default. +.. option:: -show-encoding + + Enable the printing of instruction encodings within the instruction info view. + .. option:: -all-stats Print all hardware statistics. This enables extra statistics related to the @@ -415,10 +419,10 @@ an indicator of a performance bottleneck caused by the lack of hardware resources, and the *Resource pressure view* can help to identify the problematic resource usage. -The second section of the report shows the latency and reciprocal -throughput of every instruction in the sequence. That section also reports -extra information related to the number of micro opcodes, and opcode properties -(i.e., 'MayLoad', 'MayStore', and 'HasSideEffects'). +The second section of the report is the `instruction info view`. It shows the +latency and reciprocal throughput of every instruction in the sequence. It also +reports extra information related to the number of micro opcodes, and opcode +properties (i.e., 'MayLoad', 'MayStore', and 'HasSideEffects'). Field *RThroughput* is the reciprocal of the instruction throughput. Throughput is computed as the maximum number of instructions of a same type that can be @@ -427,6 +431,31 @@ example, the reciprocal throughput of a vector float multiply is 1 cycles/instruction. That is because the FP multiplier JFPM is only available from pipeline JFPU1. +Instruction encodings are displayed within the instruction info view when flag +`-show-encoding` is specified. + +Below is an example of `-show-encoding` output for the dot-product kernel: + +.. code-block:: none + + Instruction Info: + [1]: #uOps + [2]: Latency + [3]: RThroughput + [4]: MayLoad + [5]: MayStore + [6]: HasSideEffects (U) + [7]: Encoding Size + + [1] [2] [3] [4] [5] [6] [7] Encodings: Instructions: + 1 2 1.00 4 c5 f0 59 d0 vmulps %xmm0, %xmm1, %xmm2 + 1 4 1.00 4 c5 eb 7c da vhaddps %xmm2, %xmm2, %xmm3 + 1 4 1.00 4 c5 e3 7c e3 vhaddps %xmm3, %xmm3, %xmm4 + +The `Encoding Size` column shows the size in bytes of instructions. The +`Encodings` column shows the actual instruction encodings (byte sequences in +hex). + The third section is the *Resource pressure view*. This view reports the average number of resource cycles consumed every iteration by instructions for every processor resource unit available on the target. Information is |
